Ampex F4460 reel to reel.

[captainvi...@gmail.com]

I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

[N_Cook]

What gives the speed change? conical/stepped jockey assembly out of
registration?

[N_Cook]

Perhaps a tyre cracked and fallen off , but running against the pulley
itself now.

[William Sommerwerck]

The motor is running 3% slow, not 25%. So the problem has to be somewhere
between the motor and the capstan.

[captainvi...@gmail.com]

Well I'm afraid that I misstated something. The Strobotac was actually aimed at the motor pulley, not the capstan. The speed reading that I got of 1795 RPM was in fact the motor pulley speed. The capstan of course would be spinning much slower.

So William, you mentioned 3 percent. I'm assuming that's 3 percent of 1850? Are you thinking that if I could bring my speed up 3 percent my sine wave would in fact then occupy a 1.0ms. period? And how would you increase the speed of a synchronous motor? Lenny

[Mike]

On Wed, 17 Dec 2014 08:46:01 -0800, captainvideo462009 wrote:
>
> Well I'm afraid that I misstated something. The Strobotac was actually
> aimed at the motor pulley, not the capstan. The speed reading that I got
> of 1795 RPM was in fact the motor pulley speed. The capstan of course
> would be spinning much slower.
>
> So William, you mentioned 3 percent. I'm assuming that's 3 percent of
> 1850? Are you thinking that if I could bring my speed up 3 percent my
> sine wave would in fact then occupy a 1.0ms. period? And how would you
> increase the speed of a synchronous motor? Lenny

I don't remember working on reel-to-reel decks. But have a couple of
thoughts. Is this a (clean?) belt drive between motor and capstan? Was the
"load" test with the motor or capstan being braked? Does the capstan have
to turn the full spool and does it rotate freely? Does helping manually
make any difference?

Mike.

[captainvi...@gmail.com]

On Wednesday, December 17, 2014 12:53:27 AM UTC-5, captainvi...@gmail.com wrote:

To answer your questions Mike yes there is a flat belt from motor pulley to capstan flywheel, (see further explanation on that below). The load test on the motor was putting a drag on it with my finger as it was turning. It had no trouble maintaining speed as observed with the strobe tach. i don't understand what you mean when you ask if the capstan has to turn the "full spool". As far as helping manually there really is no way to help manually other than by decreasing the hold back tension. I tried that too but it didn't make much difference. What follows is some further information.

One other thing that I didn't mention was the the main drive belt. It is a flat belt which is roughly 2.0mm thick and has a circumference of approximately 35cm. The other belts are basically just different sized O rings which only needed the slick stripped off of them to expose some good grippy rubber. I had to do that with the capstan pinch roller as well. I used a bit of lacquer thinner on the belts and sand paper and thinner on the roller too to get to some good rubber

The OEM flat belt though was very tired and had "assumed the position" of an oval from sitting in one position unused for so long. I couldn't find anything around here having that circumference that was 2.0 mm thick so as a temporary measure I substituted a much thinner belt. There is a very slight amount of wow which can be seen when looking at the capstan flywheel with the strobe using this substitute belt, and I'm guessing that it could be stretching back and forth ever so slightly as it spins, but you really don't notice it on music and it's only temporary until I can find something a little more appropriate. I wouldn't think that a thinner belt would contribute to a speed error, or am I wrong in making that assumption? Lenny

[chuck]

On Wed, 17 Dec 2014 10:18:41 -0800 (PST), captainvi...@gmail.com
wrote:

Lenny,

About 12 years ago I had a Crown R to R that would not play tapes at
the correct speed and it turned out to be the motor. I had lubed the
bearings and there was very little rotational resistance but still the
speed was incorrect. I got a rebuilt motor from a former Crown
employee and the speed was spot on. I never found out what caused the
problem. Chuck

[captainvi...@gmail.com]

On Wednesday, December 17, 2014 12:53:27 AM UTC-5, captainvi...@gmail.com wrote:

I'm thinking along those lines too but do you think that 55RPM slow would cause such a drastic slowdown on playback? Here is another interesting observation. I have a another similar Ampex junker in the shop. It is a different model but a similar chassis. The motor is a 2 wire job from a different contractor and apparently with no external capacitor. The motor pulley, capstan, flywheel, etc all look the same. I had considered trying to swap motors but decided to do a speed test on the other one first. It spins up at 1680 RPM. So either there are different sized parts in that chassis, or that motor is bad too. Lenny

[Sofa Slug]

On 12/17/2014 10:18 AM, captainv...@gmail.com wrote:

>> The OEM flat belt though was very tired and had "assumed the
>> position"
> of an oval from sitting in one position unused for so long. I
> couldn't find anything around here having that circumference that was
> 2.0 mm thick so as a temporary measure I substituted a much thinner
> belt. There is a very slight amount of wow which can be seen when
> looking at the capstan flywheel with the strobe using this substitute
> belt, and I'm guessing that it could be stretching back and forth
> ever so slightly as it spins, but you really don't notice it on music
> and it's only temporary until I can find something a little more
> appropriate. I wouldn't think that a thinner belt would contribute to
> a speed error, or am I wrong in making that assumption? Lenny

I would put the correct belt on there before getting into other minutia,
otherwise you may just end up chasing your tail.

[Bruce Esquibel]

captainvi...@gmail.com wrote:


> If anyone has any thoughts on this I'd sure appreciate hearing them.

I have one stupid idea, is there a switch somewhere on the rear panel for
changing the line cycles from 50hz to 60hz?

I remember some older Akai decks (1710/20/30 come to mind) has this along
with a mechanical voltage selector for the unit, from 100vac to 220.

I just seem to remember if the 50/60hz switch was wrong, there was a speed
problem with the capstan motor, although I think it was along the lines of
running fast (switch on 50hz when you are feeding in 120v/60hz).

There is a fairly large ratio on the capstan, figuring the diameter that
goes against the pinch roller is 1/4" or less and the flywheel part was 5
or 6 inches (at least), it's like 25:1 or 30:1.

Everything seems to point to the belt, because that usually is all that is
there between the motor and flywheel but I've see broken belts, belts with
flat spots, belts that turned into glue but none of them from memory that
would cause a constant 25% loss of rpm. No rotation or really bad wow and
flutter.

I'm guessing if it'a "universal hysteresis" motor and the machine was
designed for 100v to 220v without adapters, it's in the voltage or cycle
selection somehow.

It might even be a mechanical adjustment. Just occured to me the earlier
AKAI units had like a screw driver slot to change the motor speed via tossing
it on a different pully off the motor. The hole was marked 50/60hz.

If the shaft has a dual pulley, might just be on the wrong one.

-bruce
b...@ripco.com

[captainvi...@gmail.com]

On Wednesday, December 17, 2014 12:53:27 AM UTC-5, captainvi...@gmail.com wrote:

Those are some great ideas Bruce but I think I've been down that whole road already. The machine is definitely from the US market only, that is 115V 60 cyc marked. Yesterday I tried putting a small AC cap in parallel with the original 3uf cap. It made the motor hum and slowed it down. Today I'll try decreasing the capacitance slightly and see what happens. I'm running out of tricks though. I still have to wonder though would a 55RPM drop in motor speed cause the degree of speed problem I'm seeing on the tape? Lenny

[William Sommerwerck]

wrote in message news:9a5b307e-8fa0-467b...@googlegroups.com...

> Those are some great ideas Bruce but I think I've been down that whole road
> already. The machine is definitely from the US market only, that is 115V

> 60Hz

> marked. Yesterday I tried putting a small AC cap in parallel with the
> original
> 3uf cap. It made the motor hum and slowed it down. Today I'll try decreasing
> the capacitance slightly and see what happens. I'm running out of tricks
> though.
> I still have to wonder though would a 55RPM drop in motor speed cause the
> degree of speed problem I'm seeing on the tape? Lenny

As I pointed out, it's a 3% change. Gears and pulleys work on ratios, not
absolute values. The motor appears to be basically "on speed", so the problem
has to be somewhere else.

This is not a personal remark, just a statement of what I see as fact. It
appears that you don't understand much about mechanical systems. You need to
find someone who feels comfortable with them, and have him take a look,

[jurb...@gmail.com]

Well that clears up a couple questions I was going to ask. If you are our Lenny, I thought you were in the US but really never knew it for sure. Never gave it a thought.

However, looking at the responses I see a few things. for one, the 50/60 Hz sitch or whatver, if wrong would make it run fast. Having worked on this kind of shit I say the following :

First, when you measure the RPM of the motor, is that with the belts etc. disconnected ?

With everything disconnected, does the shaft turn freely ? If you just give it a flick it should keep turning from its own momentum.

Same is true of the flywheel and capstan.

Belts typically lose a few RPM here and there, alost always. that is why there are TEETH on the timing belt in cars. Of course teeth here would cause flutter. Capstan bearings can get sticky. What's more alot of them wear out and then the capstan is not held at the correct angle. If you have a bearing problem I could actusally make one if I can get the brass stock, but there is a workaround. the bearing is usually screwed to the main chassis2 by three screws. Most of the tiome you can rotate the bearing and the capastan will align because all the pressure is against fresh parts of the surface. Of course it is possible that this has already been done if you are not the original purchaser.

So get everything disconnected and turn things freehand. Also, with the belt off, engage the pinch roller. It should not cause all that much drag. If so, you might have a groove worn into the capstan bearing.

Actually I should call it a bushing, they are usually brass. I have never seen one with ball bearings.

Sometimes you can tell if the bushings are worn by the behavior of the tape as it goes through. you, I think you would have noticed that but it can also be insidious. It all depends on the architecture of the machine. there is a force applied by the pinch roller, and there is a force applied by the belt or idler. These cause a certain wear pattern. This varies of course because of whatever angle the belt or pulley comes from, but of course the force from the pinch roller is always perpendicular to the tape path, or close.

If you don't figure this out soon I will see if maybe hifiengine has rthe manual for it and give it a look. It sounds like you will figure it out but you need to get back to basic mechanics.

Incidentally, I THINK (not totally sure) that if the cap starts going bad on a cap run motor it will still turn about the same RPMs but pull more current. that fact that irt is a little low means maybe the cap is really bad and the load is pulling it out of synchronicity. So it matters if you check it under load or not, and actually to see if there is a major difference.

We had a discussion about that on one of the sci dot whatevers a couple years ago about replacing the capacitors in people's central AC units, that is could save them money. Years ago my Mother's house was hot in the summer because it was so damn expensive to run the air. Then it quit completely. Atr I threw in a run cap it was alot cheaper to run. But the thing is that it seems like these things just run at the right RPMs until theyu do not run at all, IN THAT APPLICATION.

Friggin R2Rs, why the cap ? And change the cap for 50 Hz and all that shit. why didn't thwey just use a brushless slotless DC motor ?

Oh yeah. Oldness. I can feel it.

[captainvi...@gmail.com]

On Wednesday, December 17, 2014 12:53:27 AM UTC-5, captainvi...@gmail.com wrote:

In the early 1970's I was the service manager for a broadcast and recording equipment company. I worked on a lot of Ampex, Scully, Revox, etc. professional machines. This unit, the F4460 although an Ampex was built for the consumer market. and although the electronics was superb, just about up to par with the professional machines, the transport however left a lot to be desired.

To keep the costs down, (under a grand at the time, I think) they had to chinch on something, and it was the deck. The studio machines employed three motors. There was a main, and also a take up, and a hold back motor. These two torque motors would not spin during normal operation but were used to maintain proper tape tension on the heads.

Ampex had a few of these consumer type machines on the market at the time that used similar other cheaper techniques to try to accomplish the same thing as the pro machines. For instance Instead of a take up torque motor there was a slipping clutch on the take up pulley. And for hold back tension, instead of a motor tensioning the tape across the heads a felt washer jammed the tape against a guide on the left side of the machine. This washer would eventually load up with tape material, the transport would start wowing and the washer would have to be removed, cleaned with alcohol and reinstalled. A pain in the ass but worth it to have an Ampex.

I didn't ever really recall ever having a speed problem like I'm having with mine with one of these consumer type machines, or even ever having to check speed as referenced from an alignment tape as I did here with the scope. They just always seemed to be on speed.

So Jurb to answer some of your questions, or suggestions, yes I am in the US, New Hampshire to be exact. We haven't seceded from the Union yet, although sometimes I wish we would. I tried checking RPM both ways; unloaded and then loaded with belts capstan engaged, and then "overloaded" (the finger on the pulley test). And through it all the motor maintained constant torque and speed. Both the motor and flywheel turn freely. The motor actually has two fill holes for each bushing. I was able to stick a hypo filled with 10W into each hole and hit what seemed like a felt sponge around an oilite bearing. Besides if either one of these items was stiff I would expect to see a speed fluctuation problem, which I don't. The capstan bushing is also tight. Other than that I can add that this machine had a very easy life before I acquired it. It was hardly used at all. Tomorrow I'll play with the cap value and see what happens.

Really thought this thing would be off my bench by now, and back in the entertainment center and I'd be listening to my Grateful Dead tapes. Fucken bummer. Lenny

[jurb...@gmail.com]

Fuck Lenny I am way cooler than you, or was...

I had me a Viking Of Mineapolis. It was not only tube, the optional record amplifiers could be removed, unplugged. Whether yuo bought into the record capability was irrelevant however, to the playback. All you needee was a preamp the had tape (NARTB equalized) inputs. Just so happens I had one, and for the life of me I can't reme,mber the make and model of it. It MAYT have been an H.H. Scott but don't take that to the usury.... er .. bank.

Anyway, to get back to your dilemma. At this point I suspect your tachometer. That ia not a large error. Hoever this does not explain the much larger error in the actual tape speed.

Here is something interesting just occurred to me, you know tape does not shrink. Is it possible that the slight error in motor speed combined with the tape being stretched has resulted in the cumulative error you obseved ?

Really, 700 some Hz is way off of 1,000. You can REALLY hear that. You said it sounded slow, I guess it was. But why.

Ihave fucked with a couple of reel to reels laely and I see the tape is not what it once was, n fact me and my little crew have zero good tape. The best shit we got right now clogs up theheadss in like, half hour or something. It still plays but the level keeps dropping. I looked at the prices of new tape and decided, not.

These are really cool. When I hit the lottery I will send a minion to pick me one up... I have digital solution anyway, but I still think they're cool. In fact my buddy has a nice Teac he is probaably going to sell. I worked on it, it is a fucink nice deck, really. Takes the 10" reels. Four track simulcord. Though it is a three head, it can switch the playback head to the record head in sound on sound to keep the sound in sync. Otherwise yoy owuld have to waste a generation on every overdub. Or whatever. Ask Les Paul lol. you know whatI mean. The thing is a practical recording studio.

I oculd not get nfo on your Ampex from the usual sources. I did however score in the 99th percentile in mechanical reasoning in one of them thar pre SAT typee thingies when I was young. I mean before I crashed a car young, and that means young. All those idlers and shit, unless ther eis a driven shaft rubber wheel (whiich is not an idler) or some type of stepped thing, the size does not really matter.

An idler by definition is not driven by its shaft. If it is, it is a drive wheel, not an idler.

For example, on a record player if you were to make the idler wheel a bit bigger, the speed would not change except for maybe what the rubber drags it down or something. Ther math has not changed because the only numbers tha tmatter are those of the SFM of the motor shaft and the SFM of the driven flywheel which is either the tunrtable or the alumin(i)um thing attched to the capstan. Math it math.

It is usual to have that much of a speed error on something like that, but of course that explins your presence here...

Anyway, the way I see it is suspect the RPM meter about the motor, OR maybe those extra wires go to the cap to trim the speed. (???) Now that would be tripped out. But tell you what, it is very possible.

Look see if there is any rubber in that thing that is nailed down. By that I mean a driven shaft with a rubber surface driving something. There is a good reason they stuck with the metal motor shaft and the final dirven thing, those two diaameters make the ratio and that is that. Other designs not so much.

hell, you might have to rewire the capacitor to give more RPMs. Seriously, that is possible.

Wish ?I oculd get a mmanual ion that thing, dammit

[jurb...@gmail.com]

>"It is usual to have that much ..."

Of course I meaant unusual but forgot the un part.

Have an uncola.

[Sjouke Burry]

Maybe a silly suggestion, but check your scope 1khz signal.
Because those are not very reliable signal sources, specially
in old scopes. The square wave is usually oke, but the frequency
might be off. Maybe your voltmeter has a frequency measurement range.

[Phil Allison]

Sjouke Burry wrote:


>
> Maybe a silly suggestion, but check your scope 1khz signal.
> Because those are not very reliable signal sources, specially
> in old scopes. The square wave is usually oke, but the frequency
> might be off. Maybe your voltmeter has a frequency measurement range.

** That might be the case OR the capstan roller has gone smooth and hard with age and is failing to control the speed of the tape through the capstan gate.

With this sort of defect, tape speed can increase or decrease, depending
whether the take up reel or supply reel has more torque. A simple test is to see if it is easy to pull tape through the capstan gate with the machine turned off - if it is, you have a problem.

Having serviced many Roland tape echo machines made back in the 1980s (the famous Space Echo and Chorus Echo models ) I can say the one fault common to practically ALL examples seen is a shiny, smooth pinch roller.

Since no new supply of suitable rollers exists, I fit the old one with a suitable shaft and lock it into the chuck of a bench drill spinning at 600rpm - then, using finger pressure on a piece of fine sand paper wrapped around strip of wood, gently remove the shiny surface & restore the needed matt one.


... Phil

[Mark Zacharias]

"Sjouke Burry" <burrynu...@ppllaanneett.nnll> wrote in message
news:5493c99f$0$28003$703f...@textnews.kpn.nl...

I have seen older machines run slow because the idler wheel has dried out so
much that it's circumference has actually contracted noticeably.

Also, do not rule out an issue with the motor pully - the idler could be
running at a slightly lower height, if the pulley has a curved face. The
motor mounting bushings could be deteriorated, causing a height issue.

In my experience - if it were the motor cap, it would slow down and stop.
Also, the cap would probably be leaking noticeably, possibly also getting
hot.


Mark Z.

[Phil Allison]

Mark Zacharias wrote:

> I have seen older machines run slow because the idler wheel has dried out so
> much that it's circumference has actually contracted noticeably.

** Got some news for you - pal.

The exact diameter of an idler wheel is irrelevant.

Cos all any idler does to transfer the surface speed of one rotating object to another.


.... Phil

[Tim Schwartz]

Good morning,

While I realized that the model is a F4460, is the machine what they
also call an F-44? The last 2 digits might just tell you what speeds or
cabinet the machine came in, or if it was 1/4 or 1/2 track.

Anyway, if it is an F44 (Fineline 44?) I have a recollection of what
Ampex techs call a "Dropped capstan flywheel" This is where the large
cast flywheel dropped down on the capstan shaft be cause the press fit
wasn't tight enough. I think you can check this by taking the top panel
off the unit so you can really see the flywheel, and just try pulling up
on it. If that's the case then you can take the whole thing out of the
machine, clean the capstan shaft and flywheel from grease, and refit the
flywheel with some epoxy so it stays where it it supposed to.

If this is an F44, contact me off-group. I might have a manual for the
thing somewhere in the archives.

Regards,
Tim Schwartz
Bristol Electronics

[Gareth Magennis]

"Phil Allison" <palli...@gmail.com> wrote in message
news:ceb575a3-eda7-4259...@googlegroups.com...

This stuff is really good on pinch rollers.
http://www.amazon.co.uk/AF-International-Platen-Cleaner-Restorer/dp/B0012IKSHO/ref=sr_1_1?ie=UTF8&qid=1419000776&sr=8-1&keywords=platenclene


I once bought a bottle of Teac pinch roller cleaner, and it was totally
useless.



Gareth.

[Mike]

On Fri, 19 Dec 2014 14:56:02 +0000, Gareth Magennis wrote:

> Since no new supply of suitable rollers exists, I fit the old one with a
> suitable shaft and lock it into the chuck of a bench drill spinning at
> 600rpm - then, using finger pressure on a piece of fine sand paper
> wrapped around strip of wood, gently remove the shiny surface & restore
> the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape. It is the capstan that needs that. I can see you might need some
resilience so that the tape is not nipped too tightly and thus reduce the
contact pressure, but that's not really a surface attribute.

Mike.

[Gareth Magennis]

"Mike" <ne...@mjcoon.plus.com> wrote in message
news:T6qdnd5SDoGz3gnJ...@brightview.co.uk...

I didn't write that, Phil Allison did.



Gareth.

[Jon Elson]

captainvi...@gmail.com wrote:


>
> So I next got out the Strobeotac and put it on the motor capstan. The
> motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795.

1850?? How can the motor do 1850 on 60 Hz power? Many tape decks used
hysteresis-synchronous motors, so they were designed to spin up as
induction motors and then lock to the mains as synchronous.
A 4-pole motor would run at exactly 1800.0 RPM.

1795 with a strobotac is probably 1800, and your strobotac is
just a hair off calibration. You might just use a nean lamp
in series with a resistor and diode to make an exact 60 Hz
strobe, and see if a mark on the motor shaft stands still.


Jon

[Phil Allison]

Mike wrote:

>
> Phil Allison wrote:
>
> > Since no new supply of suitable rollers exists, I fit the old one with a
> > suitable shaft and lock it into the chuck of a bench drill spinning at
> > 600rpm - then, using finger pressure on a piece of fine sand paper
> > wrapped around strip of wood, gently remove the shiny surface & restore
> > the needed matt one.
>
> But why does it matter? The pinch roller does not need friction to the
> tape.

** It absolutely does.

The simple explanation is in the words you snipped.

> It is the capstan that needs that.

** The capstan has no grip to the tape - since polished steel and smooth tape have no mutual friction.

> I can see you might need some
> resilience so that the tape is not nipped too tightly and thus reduce the
> contact pressure, but that's not really a surface attribute.

** A shiny surfaced roller has no grip to the capstan.

Why the heck do you think pinch rollers ( along with idler tyres and drive belts) are made from soft rubber in the first place ?

You ever serviced a tape recorder in your life ?


.... Phil

[Mike]

No need to be rude! Actually I have only serviced special purpose players,
for a decade or three until they were discarded in favour of CD drives.
The media are all pre-recorded.

I said why I thought the pinch roller needed to be resilient; just a
matter of physics and pinch pressure. But now I see that you are relying
on an unstated but reasonable assumption: that the pinch roller is wider
than the tape so gets driven by the capstan on its margins and drives the
tape between those margins. You could, of course, have explained that
instead of ranting...

Mike.

[Phil Allison]

Mike wrote:
Phil Allison wrote:
:
> >>
> >> Phil Allison wrote:
> >>
> >> > Since no new supply of suitable rollers exists, I fit the old one
> >> > with a suitable shaft and lock it into the chuck of a bench drill
> >> > spinning at 600rpm - then, using finger pressure on a piece of fine
> >> > sand paper wrapped around strip of wood, gently remove the shiny
> >> > surface & restore the needed matt one.
> >>
> >> But why does it matter? The pinch roller does not need friction to the
> >> tape.
> >
> > ** It absolutely does.
> >
> > The simple explanation is in the words you snipped.
> >
> >
> >> It is the capstan that needs that.
> >
> > ** The capstan has no grip to the tape - since polished steel and
> > smooth tape have no mutual friction.
> >
> >> I can see you might need some resilience so that the tape is not nipped
> >> too tightly and thus reduce the contact pressure, but that's not really
> >> a surface attribute.
> >
> > ** A shiny surfaced roller has no grip to the capstan.
> >
> > Why the heck do you think pinch rollers ( along with idler tyres and
> > drive belts) are made from soft rubber in the first place ?
> >
> > You ever serviced a tape recorder in your life ?
>
> No need to be rude!

** Nothing rude about what I posted.

You clearly have no idea how a capstan tape drive works.

> I said why I thought the pinch roller needed to be resilient; just a
> matter of physics and pinch pressure.

** Makes no sense.

> But now I see that you are relying
> on an unstated but reasonable assumption: that the pinch roller is wider
> than the tape so gets driven by the capstan on its margins and drives the
> tape between those margins.

** Whaaaaattt - so you have never seen a capstan drive tape machine ?

Yet you still decided to argue with me about my clearly written, totally correct post, by snipping and ignoring the bits you completely misunderstood.

> You could, of course, have explained that instead of ranting...

** The one rating is YOU - pal.

FFS - YOU could have admitted that YOU had no idea how a capstan tape dive worked instead of making guesses and bullshitting.

FYI:

The pinch roller is CRUCIAL to the operation - it traps the tape against the capstan shaft and resists tensions coming from the supply and take up reels. The roller's height is about twice the width of the tape so it contacts the capstan directly and is driven around by it.

The pinch roller is generally mounted on a spring loaded arm, which is held back opening a small gap unless the machine is in play or record mode. When in play or record mode, the spring loaded arm is released and holds the pinch roller firmly against the capstan trapping the tape in between.

The roller must have a flat surface, with a good amount of grip to the capstan shaft when engaged. It must also grip the tape and the shaft it turns on must be exactly parallel with the capstan itself.

A worn or old pinch roller typically has a "glazed" surface that has almost no grip to the capstan or tape - or else it may become barrel shaped. A barrel shaped roller skews the tape up or down the capstan, causing the tape to spill or wind around the roller.

With a cassette deck or VCR, the capstan drive mechanism is hidden from the operator - but with a reel to reel recorder or tape echo it is highly visible cos the tape must be manually threaded through the capstan gate.

As Pete Townshend famously said " .. the simple thing you see are all complicated ... "

Capice ?


... Phil

[Cydrome Leader]

I have to admit that your explanations for pinch rollers is dead on. A worn or dry roller would cause slippage though, so rough it up and try again.

As for the OP, Not sure how much I'd trust a 400 year old tach. It may be time for a cardboard disc and a neon light to check for speed problems with the motor.
You don't need as many lines as on a turntable either.

[Tim Schwartz]

On 12/17/2014 12:53 AM, captainvi...@gmail.com wrote:
> I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.
>
> So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.
>
> The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.
>
>
> If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny
>

Hello everybody,

I doubt that his issue is a pinch roller no matter how badly glazed it
is as his machine is running SLOW, and it the tape is being pulled ahead
by the take-up torque overpowering the capstan/pinch roller, it would be
running fast.

[Phil Allison]

Tim Schwartz wrote:

>
> doubt that his issue is a pinch roller no matter how badly glazed it
> is as his machine is running SLOW, and it the tape is being pulled ahead
> by the take-up torque overpowering the capstan/pinch roller, it would be
> running fast.
>

** But a capstan spinning against a glazed roller will slip and hence not drive it round at full speed.

Most of my recent experience is with Roland tape echoes which use a 5 metre long loop squirming around in a box. Back tension come from pairs of felt pads the tape passes between as it leaves and enters the box.

When the roller is glazed, tape speed is slow and unsteady.

Also, tape becomes slightly sticky with age and grips to the heads as it passes over them - so much so that in some cases the loop will stop moving completely until you lift the tape off the heads and start again. This is the case even when the pinch roller in perfect condition.

The fix here is to clean all the heads and guides and replace the loop.

.... Phil

[Colin Horsley]

> .... Phil


Excellent description Phil.

Thank you

Col

---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com

[Arfa Daily]

"Gareth Magennis" <sound....@btconnect.com> wrote in message
news:xcqdndpBw4IXoQnJ...@bt.com...

Oh you little darlin' Gareth ! This was one of my favourite workshop
chemicals. I had one and it lasted years and years. When it ran out, I
really mourned as I was unable to find it still for sale anywhere. As soon
as Crimbo is out of the way, I will be ordering a can ! :-)

Arfa

>
>
> Gareth.
>
>
>

[Arfa Daily]

"Sofa Slug" <sofa...@invalid.invalid> wrote in message
news:m6ssvi$ifg$1...@dont-email.me...

Seconded. I have had many Aiwas that use a single motor dual cassette deck
come through my workshop over the years, that have had the main drive belts
replaced with two of dissimilar thicknesses. One might be a 1 mm square
section and the other 1.2 mm. When this is the case, it is impossible to get
both decks running at the same speed, even though it is a single motor
driving both. When two belts of the same thickness are fitted speed on both
decks is identical.

Arfa

[Michael A. Terrell]

Arfa Daily wrote:

>
> "Gareth Magennis" wrote:
> >
> > This stuff is really good on pinch rollers.
> > http://www.amazon.co.uk/AF-International-Platen-Cleaner-Restorer/dp/B0012IKSHO/ref=sr_1_1?ie=UTF8&qid=1419000776&sr=8-1&keywords=platenclene
>
> Oh you little darlin' Gareth ! This was one of my favourite workshop
> chemicals. I had one and it lasted years and years. When it ran out, I
> really mourned as I was unable to find it still for sale anywhere. As soon
> as Crimbo is out of the way, I will be ordering a can ! :-)

I took a quart glass bottle to a local print shop and they filled it
with platen cleaner for $10. They buy it in 55 gallon drums. Smaller
shops buy it in five gallon cans.
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

[Michael A. Terrell]

Tim Schwartz wrote:
>
> Good morning,
>
> While I realized that the model is a F4460, is the machine what they
> also call an F-44? The last 2 digits might just tell you what speeds or
> cabinet the machine came in, or if it was 1/4 or 1/2 track.
>
> Anyway, if it is an F44 (Fineline 44?) I have a recollection of what
> Ampex techs call a "Dropped capstan flywheel" This is where the large
> cast flywheel dropped down on the capstan shaft be cause the press fit
> wasn't tight enough. I think you can check this by taking the top panel
> off the unit so you can really see the flywheel, and just try pulling up
> on it. If that's the case then you can take the whole thing out of the
> machine, clean the capstan shaft and flywheel from grease, and refit the
> flywheel with some epoxy so it stays where it it supposed to.
>
> If this is an F44, contact me off-group. I might have a manual for the
> thing somewhere in the archives.

I saw a lot of loose flywheels on cheap 8-track tape decks around
1970. We would pull the capstan and flywheel, then use a small center
punch and hammer to put four equally spaced dents near the capstan, on
the bottom side of the flywheel.

[dave]

It's the lack of pliabililty. They call it a pinch roller because it
pinches the tape. A hard rubber puck is useless. The exact dimension
isn't critical as long as the bearings fit and the plunger goes far enough.

[Phil Allison]

dave wrote:
>
> >> Phil Allison wrote:
> >>
> >>> Since no new supply of suitable rollers exists, I fit the old one with a
> >>> suitable shaft and lock it into the chuck of a bench drill spinning at
> >>> 600rpm - then, using finger pressure on a piece of fine sand paper
> >>> wrapped around strip of wood, gently remove the shiny surface & restore
> >>> the needed matt one.
> > >
>

> It's the lack of pliabililty. They call it a pinch roller because it
> pinches the tape. A hard rubber puck is useless. The exact dimension
> isn't critical as long as the bearings fit and the plunger goes far enough.

** You must be thinking of pinch rollers used in VCRs which often have an internal ball race.

The vast majority RR and echo machine rollers simply have a plain bearing running on a shaft of about 4 or 5mm dia.

All the Roland 1/4 inch tape echos have a roller that is 12mm x 28mm running on a 6mm shaft.


.... Phil

[dave]

The rotating capstan controls the speed, the roller makes sure the tape
doesn't slip. There used to be a couple high end machines without pinch
rollers from Japan.

I spent many years fixing Ampex 600, 300, 351, 440, PR10; Otari MX5050;
ATC, Spartamatic, ITC cart machines. If the reel tension is right the
roller barely does anything.

I love when you turn the Space Echoes up too high and they make their
own music.

[jurb...@gmail.com]

Got this tape echo machine at work. Got tubes. Old. Tape runs and it was a fresh job for me. I see it has bias and audio mixing with it. It passes signal but does not echo. I think the tape is simply bad.

Anyway, it has no pinch roller. The tap goes about 1430 degrees around it though. That is apparently enough.

However O think this arraingement would cause faster tape deterioration due to more bending. Isn't the straightest path the best ? (for the tape itself of course)

It is kept under tension by a springed idler. There are no tape pads. It has a magnetic erase head between a fixed and spring loaded idler or tensioner. Lke a turing tape guide. The capstan is way over on the right side. There are like five heads, electronic heads not the PM erase head. I am probably going to change the tape soon and see what happens. I got some old ½" that is not in great shape. It will deteriorate quickly but I do know that it actually records. The stuff on there really looks funny. Red not brown. Of course that doesn't rally mean anything but that it is unusual a little. Thing is that it is not really opaque.

I am actually disappointed by the thing not hav ing a speed control. What, they didn't have eddy current motors in the 1940s ?

Cheapskates.

[Phil Allison]

jurb...@gmail.com wrote:

> Got this tape echo machine at work. Got tubes. Old. Tape runs and it was a fresh job for me. I see it has bias and audio mixing with it. It passes signal but does not echo. I think the tape is simply bad.
>
> Anyway, it has no pinch roller. The tap goes about 1430 degrees around it though. That is apparently enough.
>
> However O think this arraingement would cause faster tape deterioration due to more bending. Isn't the straightest path the best ? (for the tape itself of course)
>
> It is kept under tension by a springed idler. There are no tape pads. It has a magnetic erase head between a fixed and spring loaded idler or tensioner. Lke a turing tape guide. The capstan is way over on the right side. There are like five heads, electronic heads not the PM erase head.

** You just MIGHT be describing Charlie Watkins' famous little horror - the "WEM Copycat" first released in 1958.

http://manningsmusicals.co.uk/wp-content/uploads/2010/07/wems-007-800.jpg

A truly horrible machine that just barely worked, it's output was riddled with AC hum, tape noise (from the permanent magnet erase) and serious wow & flutter plus amplitude modualtions.

Charlie was too cheap to admit it needed a pinch roller.

Modern 1/4 inch tape normally refuses to run on a WEM Copycat as the surface friction is just too low. You could try fitting a shrink plastic sleeve over the capstan if you like.

> I am actually disappointed by the thing not hav ing a speed control. What, they didn't have eddy current motors in the 1940s ?

** Some very cheap echos used simple, DC brush motors and others had two speeds - but the first machines to feature decent, BLDC variable speed motors were made by Roland of Japan. Models include the RE101, RE201, RE301 and deluxe versions were the RE501 & SRE555.

A fairly large BLDC motor branded "Pioneer" provided direct capstan drive and continuously variable speed range of about 5:1 with varying compensation applied to EQ circuits as tape speed changed to keep the response flat. There was also an NE570N compander IC to reduce tape noise to quite low levels.

The erase head was ferrite cored and the record and play heads had stainless steel face plates that simply never wore out.

Nice machines, fixable and well worth fixing even today.


.... Phil

[captainvi...@gmail.com]

On Wednesday, December 17, 2014 12:53:27 AM UTC-5, captainvi...@gmail.com wrote:
> I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.
>
> So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.
>
> The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.
>
>
> If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

Well I thought I'd jump back in here with an update on my progress. I ordered and installed a replacement capstan flat belt from Adams Manufacturing. After installing this belt there was no more bumping from the old misshapen belt. then, I had three pinch rollers. One is from this machine and the other two were from junkers I had in the shop. The rubber on all of them was slick but seemed pliable and I worked on two of them with sandpaper and then lacquer thinner. I finished off with rubber restorer and then cleaned them off with 99% anhydrous isopropyl. After this treatment The rollers felt a bit more "grippier" if that's the correct description but still were not what I would have liked to see. However taking a fresh look at the 1KHZ tone on the test tape with the scope immediately after installing one of the "restored" rollers showed that the machine was now running on speed. So I feel foolish to admit that it seems that I had overlooked the most basic thing, the capstan roller, as being the primary governor of speed.

So I tried a few of my old tapes to see how they sounded. Some of these tapes were 1800 ft and I noticed that they would play for a coupe of songs and then start slowing down. I had a sealed brand new roll of Scotch 206, which is a 1200 ft low noise mastering tape as it's so called. I made a fine sounding recording on this tape. Then I tried playing the 3 3/4 pre recorded Bob Dylan tape. Let me tell you when Bob Dylan is off speed there is no mistaking it. So while this was running I gently increased the take up torque with my finger and the tape seemed to sound fine as long as I kept the tension up. As soon as I relaxed it a bit the speed would waver.

So now I know that for certain I need to resolve the pinch roller issue and also I need to check the take up torque for which there is a specification in the manual. Problem is I don't have a scale for that. So I as wondering if anyone knows of a source for these type of scales, and also as I found for the capstan belt is there a generic source for replacement pinch rollers? Or as a substitute can a pinch roller be "rebuilt"?

My wife just can't understand why I've been screwing around with a 50 year old machine when she has so much other shit for me to do. But I know that you guys know and can appreciate the sense of satisfaction associated with bringing a dead body back to life. And I feel like now I'm so close. Thanks for any further advice. Lenny

[jurb...@gmail.com]

>"** You just MIGHT be describing Charlie Watkins' famous little horror - >the "WEM Copycat" first released in 1958.

http://manningsmusicals.co.uk/wp-content/uploads/2010/07/wems-007-800.jpg "

That is it but I think it has a differnt name on it. It IS Watkins but I think a different word than "copicat". I'll look. they don't care they just want it to work if possible. that's why I went to hourly pay a long time ago, if it ain't worth it I still get money.

>"A truly horrible machine that just barely worked, it's output was riddled >with AC hum, tape noise (from the permanent magnet erase) and serious wow & >flutter plus amplitude modualtions. "

Well the motor is directly under the capstan. I would've take a bit different approach to say the least. Looks like a four pole or better though at least which has less flux leakage. Sometimes I wonder how these reel to reel manufacturers dealt with it. And then some with relay control of AC solenoids ! They must've been crazy back then - but then again we know they were.

>"Charlie was too cheap to admit it needed a pinch roller. "

It seems to have some type of special tape. It looks different, it is RED. I mean RED. not reddish looking normal ¼" tape, I mean RED. My fucking camera just took a shit otherwise I would put up a picture in the next few days. Hah, and guess what is in the compartment on the left. A roll of splicing tape. I do not have a splicing block but I am sure I can manage just to get it working. the tape I got laying around is too old anyway. I got even older tape with oxide falling off, htis stuff seems to wear down quickly to where it has alot of drag. Record and play, and I mean on a good deck like two Teac A-3340 and a Tandberg 9400 and shit, after a few passes it got so sticky it didn't even want to rewind. these are all three motor decks without tape pads so it is not the deck. In fact the tape with the oxide falling off rewound just fine but spewed the oxide all over the place.

>"Modern 1/4 inch tape normally refuses to run on a WEM Copycat as the surface >friction is just too low. You could try fitting a shrink plastic sleeve over >the capstan if you like. "

Well, even though it really doesn't go 1430 or whatever degrees around the capstan it might concievably work if the drag is very low. It will surely still fuck up but at least I will have a chance to test it. Getting absolutely nothing, well first of all there are more than one playbeck and NONE of them work. Logically that indicates the tape is probably FUBAR oxide wise.

You know the tape might have been coated with something. I would not approach it like that but maybe they did. Which means can't get the tape of course and nice modern tape is not likely to work well. but I can't even justify that cost. Friggin I saw sometning like $240 for a 1200' roll ? that is a bit steep but really is in line with the economy. I onder if they want to sell it by the foot. That's like buying individual cigarettes instead of a pack I guess. But still, with no pinch roller it might not have the tracktion.

Being a vintage unit I doubt I want to modify it with a pinch roller. For one I would have to establish a machine surfacr to get it straight, on a unit that is alread buiolt. Fuck all that.

Other thing, the idea about the sleeve on the capstan might not be a piece of cake unless I can find it precision, no taper etc. I do have some plastic tips for the hold down on Premier cigarette machines that really would work IF they were straight. Perpendicular and allt that, constant thickness. But they aren't. And they are not machinable.

So this thing might sit for a while. It is not a rush job to say the least.

>"A fairly large BLDC motor branded "Pioneer" provided direct capstan drive and >continuously variable speed range of about 5:1 with varying compensation >applied to EQ circuits as tape speed changed to keep the response flat. There >was also an NE570N compander IC to reduce tape noise to quite low levels. "

Yeah, try doing that with tubes. Really, I could see it happening but nowhere near the performance. Variable gain tubes, modulate the G2 voltae of pentodes and all that, it can be done.

This compander, like DBX eh ? That brings up a question.

Was there ever a tube Dolby unit ? Now that would be some engineering I think.

Enough, time to eat. I will be back at the antagonization station later.

[jurb...@gmail.com]

>"So I tried a few of my old tapes to see how they sounded. Some of these tapes >were 1800 ft and I noticed that they would play for a coupe of songs and then >start slowing down."

That is not a symptom of a bad pinch roller. I believe you might find heating up motor bearings, or capstan bearings, or maybe even a leaky motor cap. When pinch rollers go bad they usually do not wear or harden exactly uniformly and they screw up the tape path. It will hit the guides and actually even get damaged. This was VCRs, and the tape path in those is every bit as critical as audiophile or pro R2Rs if not moreso.

I would run it as far apart as possible and see if the RPMs go down playing, then see if they jump back up not. And then if they do, try to slow it down with your hand, maybe with a rag. I would do the same to the capstan.

I doubt you are mistaking muffled sound for slowing down. A pinch roller CAN cause that by affecting the tape path.

Ho about recording a test tape with like a 1 kHz signal on it. In fact make it a square wave. You can read the timing of it, and it will reveal the response curve. I say that because this whole thing doesn't sound right. There is an argument about pinch rollers now but that matters not. The load on the motor from ANY pinch roller (you kno you CAN use metal if you cna machine it well enough) should never pul down the motor RPMs. In fact even running Scotchtape (I mean the kind you stick to things) in it, it should break the tape, not stall or slow down. It should not happen. It should take a pair of Visegrips (tm) to stop that thing.

[Phil Allison]

captainvi

>
> Well I thought I'd jump back in here with an update on my progress. I ordered and installed a replacement capstan flat belt from Adams Manufacturing. After installing this belt there was no more bumping from the old misshapen belt. then, I had three pinch rollers. One is from this machine and the other two were from junkers I had in the shop. The rubber on all of them was slick but seemed pliable and I worked on two of them with sandpaper and then lacquer thinner. I finished off with rubber restorer and then cleaned them off with 99% anhydrous isopropyl. After this treatment The rollers felt a bit more "grippier" if that's the correct description but still were not what I would have liked to see. However taking a fresh look at the 1KHZ tone on the test tape with the scope immediately after installing one of the "restored" rollers showed that the machine was now running on speed. So I feel foolish to admit that it seems that I had overlooked the most basic thing, the capstan roller, as being the primary governor of speed.

** Hallelujah !!

>
> So I tried a few of my old tapes to see how they sounded. Some of these tapes were 1800 ft and I noticed that they would play for a coupe of songs and then start slowing down.

** Old tape get sticky and requires many passes through a machine to clean up, you may need to clean the heads with ISO over and over too.

I had a sealed brand new roll of Scotch 206, which is a 1200 ft low noise mastering tape as it's so called. I made a fine sounding recording on this tape. Then I tried playing the 3 3/4 pre recorded Bob Dylan tape. Let me tell you when Bob Dylan is off speed there is no mistaking it. So while this was running I gently increased the take up torque with my finger and the tape seemed to sound fine as long as I kept the tension up. As soon as I relaxed it a bit the speed would waver.

** The reel of 206 is probably sticky too - creating extra back tension that the capstan has trouble pulling through.

>
> So now I know that for certain I need to resolve the pinch roller issue

** Sanding the surface smooth while spinning the roller in a bench drill has always worked for me.

For a R-R machine to work properly, so many things have to be just right.

Not the least of which is the tape itself.


... Phil

[Phil Allison]

jurb...@

> >"** You just MIGHT be describing Charlie Watkins' famous little horror - >the "WEM Copycat" first released in 1958.
>
> http://manningsmusicals.co.uk/wp-content/uploads/2010/07/wems-007-800.jpg "
>
> That is it but I think it has a differnt name on it.

** Betcha it has "Copicat" on it.


>
> >"A truly horrible machine that just barely worked, it's output was riddled >with AC hum, tape noise (from the permanent magnet erase) and serious wow & >flutter plus amplitude modulations. "

>
> Well the motor is directly under the capstan.

** It's a regular turntable motor - with an added flywheel IIRC.

> It seems to have some type of special tape.

** Nope - the machine was meat for regular 1/4 inch tape - not too thin either.

> Other thing, the idea about the sleeve on the capstan might not be a piece of cake unless I can find it precision, no taper etc.

** Use a piece of shrink tubing - like I said.

> >"A fairly large BLDC motor branded "Pioneer" provided direct capstan drive and >continuously variable speed range of about 5:1 with varying compensation >applied to EQ circuits as tape speed changed to keep the response flat. There >was also an NE570N compander IC to reduce tape noise to quite low levels. "
>
> Yeah, try doing that with tubes.

** Would never be needed if you have proper, high frequency, AC erase and full width 1/4inch recording at 15ips.



.... Phil