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Sony TC-208 Eight-Track Deck
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Madness
Oct 10, 2015, 8:25:21 PM10/10/15
to
Replaced the belt on this deck (after spending well over an hour
cleaning out the tar-like goo that the old one had gone to). Completely
cleaned the head, trip-sensor & capstan w/ Q-tips & alcohol. Great, deck
worked fine for about a week, but has now developed an annoying flutter
(speed-variation) problem. Doesn't matter which cartridge I play,
happens w/ them all. So, after looking at the rather-spartan service
manual, I put a voltmeter across the motor to check for variations. The
manual states that there should be 20VDC across it. Running it w/o the
belt, it shows a steady 21.2V (so, no-load). But when I run a tape, I
notice the meter changes a few tenths-of-volt whenever the speed varies
(so w/ load, since I can cause the same under no-load by pressing down
on the pulley). Which makes me wonder if the capstan needs a clean-out
of old grease at its bearing. Would love to, but there's an E-clip
*under* the flywheel the holds the whole assembly in place. Would love
to know -- how-in-hell -- I'd remove that E-clip (the service manual
gives no such information)? Anyhow, if anyone has worked on this or a
similar Sony model (TC-228, 258, etc), could you please provide some
insight?
cleaning out the tar-like goo that the old one had gone to). Completely
cleaned the head, trip-sensor & capstan w/ Q-tips & alcohol. Great, deck
worked fine for about a week, but has now developed an annoying flutter
(speed-variation) problem. Doesn't matter which cartridge I play,
happens w/ them all. So, after looking at the rather-spartan service
manual, I put a voltmeter across the motor to check for variations. The
manual states that there should be 20VDC across it. Running it w/o the
belt, it shows a steady 21.2V (so, no-load). But when I run a tape, I
notice the meter changes a few tenths-of-volt whenever the speed varies
(so w/ load, since I can cause the same under no-load by pressing down
on the pulley). Which makes me wonder if the capstan needs a clean-out
of old grease at its bearing. Would love to, but there's an E-clip
*under* the flywheel the holds the whole assembly in place. Would love
to know -- how-in-hell -- I'd remove that E-clip (the service manual
gives no such information)? Anyhow, if anyone has worked on this or a
similar Sony model (TC-228, 258, etc), could you please provide some
insight?
stra...@yahoo.com
Oct 11, 2015, 2:24:30 AM10/11/15
to
Lubrication issues? Sounds like the capstan might be wobbling in the bushings.
If the belt turned to crud you can be certain the lubes are bad too.
Sony is notorious for using lousy lubricants even in $100,000 broadcast
machines.
G²
N_Cook
Oct 11, 2015, 3:46:08 AM10/11/15
to
What state the pinch wheel, hard,soft,flatted? can you invert it
,initially before replacing, and see if it makes a difference, also
changing the applied tension by finger pressure.
Are you sure you've removed all the ex-rubber black goo? it is
annoyingly persistent stuff, it could trail in from somewhere unseen
Madness
Oct 11, 2015, 11:12:18 AM10/11/15
to
On 10/11/2015 3:46 AM, N_Cook wrote:
> Is the wow cyclic? any repeat period could indicate where.
> What state the pinch wheel, hard,soft,flatted? can you invert it
> ,initially before replacing, and see if it makes a difference, also
> changing the applied tension by finger pressure.
> Are you sure you've removed all the ex-rubber black goo? it is
> annoyingly persistent stuff, it could trail in from somewhere unseen
I pretty sure that I've gotten all the goo out. Most had centered on the
> Is the wow cyclic? any repeat period could indicate where.
> What state the pinch wheel, hard,soft,flatted? can you invert it
> ,initially before replacing, and see if it makes a difference, also
> changing the applied tension by finger pressure.
> Are you sure you've removed all the ex-rubber black goo? it is
> annoyingly persistent stuff, it could trail in from somewhere unseen
motor pulley & the flywheel. As for the "pinch wheel," those are built
into each cartridge. Any idea on how I could remove the E-clip holding
in the flywheel/capstan?
N_Cook
Oct 11, 2015, 11:28:26 AM10/11/15
to
Madness
Oct 11, 2015, 1:34:07 PM10/11/15
to
On 10/11/2015 11:28 AM, N_Cook wrote:>
> Piece of cotton tied to it and then a dart point or dental sickle probe
The dental probe sounds like a good idea. Might get better access if I
> Piece of cotton tied to it and then a dart point or dental sickle probe
remove the front panel. Incidentally, if I turn the deck on its side &
play a tape, there's no flutter.
Bruce Esquibel
Oct 12, 2015, 7:54:30 AM10/12/15
to
Didn't most of the 8-track players use a self-regulated dc motor?
I don't remember what the exact name was but they were 12v dc motors that
had a built in regulator/speed control and you normally applied 14~20 volts
to them.
Usually on the flat side (opposite the shaft out side) there was a label
covering up a hole for a pot, to set the speed.
Although after all these years it probably is a bering/lube problem but the
fact that it worked a week or so before this symptom cropped up, seems a
little strange.
Kind of have a feeling it's something with the regulator circuit board
inside the motor, which even back in the day means the whole motor needs to
be replaced. Seemed like trying to take them apart pretty much destroyed
them.
Just a thought.
-bruce
b...@ripco.com
Madness
Oct 12, 2015, 9:44:43 AM10/12/15
to
After a bit of hair-pulling, I was able to remove the E-clip holding the
assembly. Relubed it w/ white lithium grease, but it didn't make much of
a difference.
Regarding the motor, yes it uses 20v (outlined in the service manual) &
has a rubber plug on the bottom, but I can't figure out how to get it
out. W/ a voltmeter across the motor, & running w/ no load, I get a
steady 21.2V. Would the voltage vary if the motor had speed issues? It
does do so, under load, in time w/ the audio fluctuations. But I can
also make the voltage drop under no load by pressing down on the pulley.
Another possible problem is that the center of my capstan is quite worn
smooth. A website (8trackavenue.com) suggests "roughing" it a bit w/ a
scouring pad inserted into the front of an empty cartridge. Gonna give
that a try, too.
Strangely, the deck will play w/o any trouble if I turn it over sideways.
assembly. Relubed it w/ white lithium grease, but it didn't make much of
a difference.
Regarding the motor, yes it uses 20v (outlined in the service manual) &
has a rubber plug on the bottom, but I can't figure out how to get it
out. W/ a voltmeter across the motor, & running w/ no load, I get a
steady 21.2V. Would the voltage vary if the motor had speed issues? It
does do so, under load, in time w/ the audio fluctuations. But I can
also make the voltage drop under no load by pressing down on the pulley.
Another possible problem is that the center of my capstan is quite worn
smooth. A website (8trackavenue.com) suggests "roughing" it a bit w/ a
scouring pad inserted into the front of an empty cartridge. Gonna give
that a try, too.
Strangely, the deck will play w/o any trouble if I turn it over sideways.
jurb...@gmail.com
Oct 12, 2015, 2:21:36 PM10/12/15
to
Sloppy capstan bearings. Look see how they're mounted. Usually there are three screws. If it is not too terribly bad you can rotate the bearings, sometimes that will work, others not. If not, you'll have to push the bushings out and find a machine shop. Actually you'll have to take them the whole thing, they can push them out.
Years ago when these things were plentiful it would not be worth doing, but now that they are a rarity it might be. I don't now what a machine shop or machinist would charge, but it is not going to be five bucks.
My lathe was bigger and would not hold the tolerance for this, plus I sold it recently. But really, to be fair as a private guy, not a shop I would probably do it for like $30. Shops generally have a per hour figure for each machine, you got a few minutes to cut the stock and not more than an hour lathe time.
The way to check this is to try to move the flywheel. It will most likely move in one direction, to and fro in relation to the front of the unit. If you turn the bearings, keep in mind which way the force will be. It is pulling the tape to the right, and it is worn in the back at the top and maybe a little at the bottom. You want ti oriented so that the force does not skew the capstan which will give you even worse problems. Think about which way it was going and the force of the tape, then decide which way to turn it.
There is a possibility that due to the mounting arrangement you cannot turn the whole bearing. If this is the case then you have to push out the bushing(s)and just rotate them. Mark EVERYTHING.
Also, if the top and bottom are identical, instead or rotating them, keep them in the same position but switch them.
We used to scrap units over shit like this, but no more. You can easily get $200 to fix a betamax now. If you can actualy do it that is ...
(I just noticed the word "betamax" is marked by my spellheck, how dare they ! I HAVE a betamax !)
Years ago when these things were plentiful it would not be worth doing, but now that they are a rarity it might be. I don't now what a machine shop or machinist would charge, but it is not going to be five bucks.
My lathe was bigger and would not hold the tolerance for this, plus I sold it recently. But really, to be fair as a private guy, not a shop I would probably do it for like $30. Shops generally have a per hour figure for each machine, you got a few minutes to cut the stock and not more than an hour lathe time.
The way to check this is to try to move the flywheel. It will most likely move in one direction, to and fro in relation to the front of the unit. If you turn the bearings, keep in mind which way the force will be. It is pulling the tape to the right, and it is worn in the back at the top and maybe a little at the bottom. You want ti oriented so that the force does not skew the capstan which will give you even worse problems. Think about which way it was going and the force of the tape, then decide which way to turn it.
There is a possibility that due to the mounting arrangement you cannot turn the whole bearing. If this is the case then you have to push out the bushing(s)and just rotate them. Mark EVERYTHING.
Also, if the top and bottom are identical, instead or rotating them, keep them in the same position but switch them.
We used to scrap units over shit like this, but no more. You can easily get $200 to fix a betamax now. If you can actualy do it that is ...
(I just noticed the word "betamax" is marked by my spellheck, how dare they ! I HAVE a betamax !)
N_Cook
Oct 14, 2015, 3:20:47 AM10/14/15
to
bearing , you can sometimes get a bit more life from the following.
Squash the bearing between 2 tiny ball bearings , set in a pair of nuts
or something, squashed in a vice. Matter of suck-it-and-see. Try low
force initially and try out with the capstan and repeat with gradually
increasing vice force
gyro_john
Dec 14, 2015, 7:47:13 AM12/14/15
to
- remove the capstan with its drive pulley.
- put it on a record player turntable and get it spinning.
- heat up the polished part of the capstan shaft with a propane torch until it would glow dark red for a few seconds.
- the spinning is an attempt to prevent warpage.
- let it cool and reassemble.
The surface will now be a dull matte finish and the traction problem is gone. Never had to do it more than once in the life of an 8-track player.
Hope this is of interest.
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