curious symptom old Fisher stereo amp, inputs strange

[Tim R]

I have an old Fisher amplifier, looks like this model

https://www.google.com/search?q=fisher+amplifier&biw=1366&bih=588&tbm=isch&imgil=QIHAkgR3TJHJ9M%253A%253Bx3bT_GyZ4ziaKM%253Bhttp%25253A%25252F%25252Fwww.icollector.com%25252FFisher-Integrated-Stereo-Amplifier_i13728010&source=iu&pf=m&fir=QIHAkgR3TJHJ9M%253A%252Cx3bT_GyZ4ziaKM%252C_&usg=__rKhDSvzeFYPjP0ZG43GdOgOEcds%3D&ved=0CCcQyjc&ei=jd5ZVeuIL4ajgwSB7IHIDg#imgrc=QIHAkgR3TJHJ9M%253A%3Bx3bT_GyZ4ziaKM%3Bhttp%253A%252F%252Fmedia.liveauctiongroup.net%252Fi%252F13488%252F13728010_1.jpg%253Fv%253D8CF479980774DC0%3Bhttp%253A%252F%252Fwww.icollector.com%252FFisher-Integrated-Stereo-Amplifier_i13728010%3B640%3B480

that I used for amplifying the laptop until it started acting funny and I replaced it with an Onkyo. It's been so long I'd forgotten what was wrong.

It's reasonably powerful, small and portable, and so I dug it out of the junk pile and used it this weekend for a harpsichord at church.

It has the usual choice of inputs (phono, cd/aux, tape in) but the only input that would work was Tape Out. It did not matter if monitor was on or off, or any mode selected.

Is that a common mode of failure? Seemed strange to me. This thing is not worth fixing, I'm sure I got it for $3 at a yard sale, but I'm curious.

[John-Del]

Not sure if you're describing this right as tape out is not an input. If that's the way it works, you definitely have a problem there. Try posting a model number. In any case, make sure it doesn't use pre amp in and pre amp out jumpers (look like chrome horseshoes) that might be missing.

[Tim R]

On Monday, May 18, 2015 at 10:04:50 AM UTC-4, John-Del wrote:
>
> Not sure if you're describing this right as tape out is not an input. If that's the way it works, you definitely have a problem there.

I'll look for the model tonight.

There are four sets of RCA sockets. REC IN, REC OUT, CD/AUX, Phono. I tried the input into all of them, only REC OUT worked. I know it's not an input, at least I think it's not supposed to be. My vague memory says it used to work on CD/AUX and when one channel stopped working I just moved it over one set. Both channels worked on REC OUT.

While it's not worth a lot of effort to me, it is still the most convenient size amp I have when I need to carry it somewhere.

[jurb...@gmail.com]

Sounds like you have a problem with the preamp section. Throw us a model number.

In that Google search, it looks like the one on the upper left ? Black front ?

If it is what I think it is, it uses a TC91XX type IC for input selection, that coulsd be bad which would be bad because you know there are no new ones out there. Believe it or not I might have one. I have a couple of old ones that vintage. One is not coming apart becaause it only has the typica blown channel, but there is another one might have it that is scrap.

It frequently does work to backfeed it through the tape output. It's not exactly the right way to do it but it works, though on some moels with some sources you get higher distortion because you are impressing the signal on an output. However, it shouldn't hurt anyrthing doing it that way.

[Tim R]

On Monday, May 18, 2015 at 11:31:54 AM UTC-4, jurb...@gmail.com wrote:

>
> It frequently does work to backfeed it through the tape output. It's not exactly the right way to do it but it works, though on some moels with some sources you get higher distortion because you are impressing the signal on an output.

Never knew that, thanks.

[jurb...@gmail.com]

So, that amp, it has tact switches and lights that tell you what source it is on ?

If they are mechanical switches, actually that is good. that means likely a simple problem. If it is electronic, you might neeed that chip.

If it is tact (not mechanical) switches, do the lights light up to indicate the selected source ? If so that is bad. If they don't light up irt is probably a power supply problem and a 2SD613 might fix you up with a 12 volt regulator or something. If the chip, WELLLLLLLL, there are solutions of one cannot be had.

Still, get that model number in here and we'll know all about it in short order.

[Leif Neland]

Tim R udtrykte præcist:

If the switch was a mecanical rotary switch, the inputs would go to the
separate pins on the switch, and the selected input would then be
connected to the viper and the tape out, and further through the volume
and tone controls to the output stage.

So the switch, whether mecanical or electronic, is dead, and you are
feeding the signal directly into the volume/tone controls.

If you don't need the other inputs, I would just cut my losses and the
connection to the switch, and just feed into the tape out, obviously
the tape out is not buffered, otherwise you would be trying to feed
signal backwards into an amplifier, which would not work.

A HiFi-nut would probably replace the switch with goldplated reed
relays anyway :-)

Leif

--
https://www.paradiss.dk
Ting til konen eller kæresten.
Eller begge.

[thekma...@gmail.com]

On some receivers/amps, the "Tape Out" RCAs were where you
connected the output FROM the cassette/tape deck - to hear
it back. Counter-intuitive, and took me time to figger out! :)

[Tim R]

Okay, this is a Fisher CA-400.

It has 5 sets of L and R RCAs on the back. They are marked Phono, Tuner, CD-Aux, REC OUT Tape, P.B. Tape. The only one that seems to work is REC OUT.

On the front there are 4 pushbuttons, for Phono, Tuner, CD-Aux, and Tape Monitor. All the buttons push in and lock, but no indicator lights of any kind appear anywhere. The power indicator light does come on.

It says 250 Watts on the back. It's a compact unit, the sound was not too bad out of it, even driving some home entertainment speakers. It would be nice if it worked. But if repair is more than a parts swap it will be beyond me. In my youth I held an Amateur Extra Class (NX9L) and I did some projects, but those days are far behind.

[jurb...@gmail.com]

I can't seem to get a print for that unit but from what you wrote I owuld bet you have a 12 volt regulator out.

If it has mechanical switches, you say the "lock" in, then it does not use that unobtainium IC. It might use some 4066 type CMOS switches but those are easy to get. But the fact there are lights not lighting means likely a supply is missing.

[Tim R]

On Wednesday, May 20, 2015 at 11:12:36 AM UTC-4, jurb...@gmail.com wrote:
> I can't seem to get a print for that unit but from what you wrote I owuld bet you have a 12 volt regulator out.
>
> If it has mechanical switches, you say the "lock" in, then it does not use that unobtainium IC. It might use some 4066 type CMOS switches but those are easy to get. But the fact there are lights not lighting means likely a supply is missing.

There are also a couple of weird outlets near the speaker terminals that appear to supply voltage to components.

I was going to throw this thing away. But if you think it's safe to use putting the input into the output sockets, maybe it is useful as is. (I mean safe as in not failing when I need it most in public.)

My memory is not reliable but I think I used it as a home stereo amplifying my laptop and feeding a couple of regular stereo speakers. And when one channel stopped working I moved the inputs over one, not realizing I was using an output, and it worked again.

[jurb...@gmail.com]

Yes, the perhiperahls ere not stand alone. Some called these rak suystems, I called them frack systems for "fake rack". But the amps did have juice. Whatever of these are left, the perips are usually gone but the amp remaians, maininly because it was nevr bat on propoerly, overheated ad fried out. Fisher did alot of shitty shit back then. Some units were OK though, for example my garage stereo is a CA-885. Don't borher looking it upo there is almost zero info on it. It is close to 200 WPC and just doesn't care. In fact it puts out over 200 WPC bu I havn't tried to measure it accurately. All I know is it ran the lathe off the speaker wires just fine. (JK)

Those outlets are usually aboiut 12 V AC or so. Yuo DO NOT have to use their particular perips, anything that pliugs in the wall wil work as long as you got cables to hook up thre audio signal. You can ru that amop with amnything, it is just the juk they sold with it is dependent upon that amp for a power source. It does not work both ways.

Bnottom linee, I bet you smack that thing hard on the fround it works. And I bet you find bad connections on a three terminal device that says someting like "7812" on it.

[Tim R]

On Thursday, May 21, 2015 at 11:05:30 AM UTC-4, Evan Platt wrote:

>
> Tape out is an output, not an input. I have an older unit. It's for
> putting the output to a tape recorder.
> --

Evan,
Here is my setup. My HP laptop feeds an M-Audio Fast Track external sound card/USB interface. RCA cables out of the M-Audio feed the Tape Out of the Fisher amplifier. Plenty of loud sound comes out of the speakers.

I have also tried this with the Fast Track feeding an Input on a Pioneer amplifier. Loud sound comes out of the speakers this way too.

Very clearly, the RCA sockets marked Output on the Fisher are functioning as an input. Also clearly, the sockets marked Inputs on the Fisher don't do anything.

Something is broken. Or, maybe outputs always work as inputs and I just never tried, I dunno.

[dansabr...@yahoo.com]

The tape out jack is essentially a fixed level audio out that comes from the switching IC. If the IC is defective, you are likely backfeeding the IC from the output into the amp. Replace the switching IC. This is likely to be a TC9163 or an LAxxxx (I don't recall the number).

Dan

[jurb...@gmail.com]

Been through that. The indicator lights are not lighting but the buttons are "locking" in. That means no TC9164. Or 3, or whatever.

[Leif Neland]

Evan Platt forklarede:

> Tape out is an output, not an input. I have an older unit. It's for
> putting the output to a tape recorder.

Tape output is connected to the connection between the input selector
and the volume/tone controls.

If there is no buffering on the output, it will also function as an
input, feeding signal to the volume/tone controls.

[Tim R]

On Friday, May 22, 2015 at 7:00:33 AM UTC-4, Leif Neland wrote:
> Tape output is connected to the connection between the input selector
> and the volume/tone controls.
>
> If there is no buffering on the output, it will also function as an
> input, feeding signal to the volume/tone controls.
>
> Leif

So is there any harm in just running it that way and using it?

[Michael A. Terrell]

jurb...@gmail.com wrote:
>
> I can't seem to get a print for that unit but from what you wrote I owuld bet you have a 12 volt regulator out.
>
> If it has mechanical switches, you say the "lock" in, then it does not use that unobtainium IC. It might use some 4066 type CMOS switches but those are easy to get. But the fact there are lights not lighting means likely a supply is missing.

https://www.samswebsite.com/en/photofact/details/index/id/50794

[jurb...@gmail.com]

Paying for the manual would be alright if I was working on it here. But for someone on the web at random, no. Can't do that.

Thanks anyway. Maybe the OP wants it though.

Interesting that is an OEM manual they say. Usually they generated their own. Are they like a licensed reseller or something now ? they used to reverse engineer almost everything, but I know that has gotten more difficult by orders of magnitude.

[Michael A. Terrell]

They ended up with the huge collection of OEM manuals the NRI had,
when that school was shut down by McGraw-Hill. I once asked about
information on a 1938 Philco tombstone radio from NRI, and they mailed
me an original service manual for free, since I had taken a course at
one time.

Sams only reverse engineered items that sold in excess of 20 thousand
units, but they collected OEM data on everything they could get their
hands on. They also wrote manuals for some company's products that
didn't meet the 20K unit minimum. Those were only available from the
OEMs.

[Phil Allison]

Tim R wrote:

> >
> > If there is no buffering on the output, it will also function as an
> > input, feeding signal to the volume/tone controls.
> >
> > Leif
>
> So is there any harm in just running it that way and using it?

** Nope.




.... Phil

[Tim R]

Okay, this is a 3 year old post, but it's MY 3 year old post.

Just out of curiosity, I tried something. I was cleaning up in the basement, and about to throw this thing out.

But first, I opened it up. Obviously I'd not done that before, because I had trouble doing it.

Anyway, I sprayed contact cleaner into every switch and worked them a bit.

Much to my surprise, it seems to be working on inputs now instead of outputs. It's the perfect size for my main internet laptop, so maybe it's a keeper. For now.

[thekma...@gmail.com]

John-Del:

On a lot of receivers/amps(esp. older ones),
'Tape Out' does mean 'coming from' the
tape/cassette deck, and 'Tape In' means
what is going out of the receiver/amp to
the record deck.

From my own experience.

[dansabr...@yahoo.com]

You have those backwards. On the receiver, the tape in "comes from" the tape.

The tape out comes from the pre-amp section prior to the volume control.

[thekma...@gmail.com]

5:36 PMdansabr...@yahoo.com wrote:
"You have those backwards. On A RECENT receiver, the tape in

"comes from" the tape.
The tape out comes from the pre-amp section prior to the
volume control. "

See my edit(caps) above.

On older gear, pre-1980, the routing of
those ins and outs as I described them
stands. How do I know? Because I
assumed the same thing you stated
above, and got no audio! Once I
flipped both RCA pairs around, Voila,
everything was fine.

[dansabr...@yahoo.com]

I won't argue your results, but with 35 years of repairing audio gear, I have not seen one yet that has that property. The in/out label on any gear is usually for that particular unit. The same exists on tape machines. There are input and output jacks there as well. The "output" jack on the tape should be activated when the tape is in play mode, thus is an output.

[John-Del]

Same here.

I'm old enough and have seen enough to know I'll never see or know everything, but I've never seen a tape monitor setup where the tape out is an input. I've got 45 years as a professional audio/video tech and have worked on many stereos, and this includes many vintage vacuum tube Scotts, Fishers, Eicos etc. from the 60s through the current HT surround receivers. But I'll never say never.

[Terry Schwartz]

Agreed --- my vintage Sansui receiver works exactly that way.

[John-Del]

I have a 70s Sansewer receiver in my dungeon, I'll see how that one is configured. But I'm wondering if the tape mon connections are simply labelled "in" and "out", or if they're preceded by "connect to"...

[tabb...@gmail.com]

Other way round. Confusion can come from the fact that on a lot of amps the selected input is connected directly to the tape output*, thus one can always use 'tape output' as an unswitched input. I say always... some amps won't work this way since there are buffers in the way, and they don't pass signal backwards.

*Phono inputs are of course preamplified first.


NT

[thekma...@gmail.com]

tabb...@gmail.com wrote: "Other way round."

Nope. I hooked the thing up via literal interpretation, and
got no playback audio from tapes, and nothing recorded
to blanks.

Once I reversed them, like I said, everything worked as it
was expected to.

And as can be seen from Terry's testimony some posts back,
I'm not the only one experiencing gear labeled counterintuitively
to how it was supposed to be hooked up.

You weren't there in either of our cases, so you can't refute
either of our experiences.

[Chuck]

On Tue, 8 Jan 2019 16:35:58 -0800 (PST), dansabr...@yahoo.com
wrote:

Me either. Audio-video tech for 30+ years.

[John-Del]

No one is calling you a liar, but after nearly 50 years repairing consumer electronics as a career, I've never seen one wired like that. To me, this means the examples you cite are aberrations or at least a very small percentage of the units in service. They could have been wired that way intentionally or maybe the jacks or TM switch were miswired. It's also possible the rear panel was simply silk-screened incorrectly or a revised version was released with the previous version's back panel.

As I pointed out above, the other possibility is that the INs and OUTs were prefaced by "connect to", which changes the context entirely. I recall some low end packaged component systems that did not use universal nomenclature, but had connection "instructions" on the back panel (ie: connect to tape deck output).

[Tim R]

MIDI in and out confuses me though.

I've never been able to get it to work except by trying it both ways.

Weird thing on this Fisher amp. Putting in headphones (and it's a 1/4 inch jack) disconnects speakers automatically. There's no way to have both room sound and headphone sound. Still it's nice to have this working again.

[dansabr...@yahoo.com]

This is a very common setup. I have received units with no sound that turned out to be a failure of the headphone jack. Without the headphones, the jack shorts the signal line to allow it to continue to the amp. If the jack does not short, then no sound. Rare, but I have seen it a number of times over the years.

[thekma...@gmail.com]

Tim R:

Are there buttons or switches on that Fisher amp
for selecting pairs of speakers?

[Tim R]

Yes.
There are two sets of speaker outputs, the A and the B.
There is a little square pushbutton, marked out for A and in for B.
With the headphone inserted, there is no sound from A whether the button is in or out. I've never put speakers on B so I've not tested that set.

Apparently you can't use two sets of speakers at the same time, or one set plus headphones. That seems curious to me. My other stereo amps don't work that way. But I'm not complaining, this little amp is perfect for what I use it for, a portable amp to get sound from a laptop I bring to various places.

[John-Del]

To further complicate things, I remember working on some cheaper amps that would put the A speakers in series with the B speakers if both A and B were selected so as not to kill the outputs with too low impedance. So if you had a pair of speakers on A and nothing on B, pushing the B would kill all sound. Used to get a few nuisance calls over that.

[thekma...@gmail.com]

Tim R:

Since there are speaker selectors then the speakers, in theory,
should not be canceled by plugging in headphones. On my 1990s
era JVC receiver, I have to remember to deselect all speakers
when listening via headphones, or I'll still be sharing what I'm
listening to with the wife - or the neighbors...! And speakers on
buss A, B, or both can still be driven with it while listening to
headphones, so I have to remember to select them out.

Sounds like yours has got some serious main board(motherboard to
us PC geeks) issues, or soldering issues.

[Tim R]

Well, I dunno about that.
Most equipment I've had if the headphone jack was 1/8, it would disconnect speakers, and if 1/4, not.
But looking at this CA-400, I can only select A or B speakers. I can't choose none. So it makes sense that the headphone would disconnect them. Maybe it's working properly.

[thekma...@gmail.com]

Tim R:

My old 1980s Sears one-piece Tuner/Phono/Cassette
had 1/4" headphone out, and it cancelled the speakers
when I plugged cans into it, just as the 1/8" on my
later bookshelf CD/Tuner/Aux.

That Fisher though sounds like one of a kind!

[Chuck]

On Sun, 13 Jan 2019 19:00:48 -0800 (PST), Tim R <timot...@aol.com>
wrote:

It is. A very common configuration.

[jurb...@gmail.com]

>"I won't argue your results, but with 35 years of repairing audio gear, I have not seen one yet that has that property. The in/out label on any gear is usually for that particular unit. The same exists on tape machines. There are input and output jacks there as well. The "output" jack on the tape should be activated when the tape is in play mode, thus is an output. "

That has not been my experience. In most amps the tape output is pretty much at the output of the input selector, or in the case of a Yamaha for example, form another separate selector. As such it can be backfed.

If it is buffered or even resistor isolated that will not work so well, but it seems the engineers decided that the low output impedance as worth it to keep the noise down. As such, not only can it be backfed, it can also be shorted by the wrong thing connected and cause no output. I got this DCD Pro CD player, commercial, like DJ model. I had it temporarily hooked up wrong because I couldn't really see in the back, it was going IN to the tape OUT. Well when the CD player was shut off it apparently shorts the outputs and that resulted in no sound from any source.

In another case I had a VHS HIFI, a Sanyo VCR-7200 that when turned off got non linear at the record INPUTS. It caused severe distortion unless it was turned on. It is easy to figure out why, the input stage was probably diode protected against overvoltage and when the power supply dropped, the shunting was to zero volts.

It is a piece of wire, the "current" can go both ways.

I didn't mention it before I think, but some of those units used a TC9164 or something as a selector chip and those did go bad. I had to change a bunch of them back when. That was how they were - the tape output was the only "input" that would work.

What I don't remember is if those chips fed a CMOS switch set or had it onboard. Like 4066s, or the cheaper one, 4016 ? Whatever.

I could probably find a print and find out but why don't you just to it ? Right from Google you got Electrotanya, and then there is hifiengine and hifimanuals. You need a membership to the latter two but they don't charge, they don't spam or any of that. I got nothing but good to say about those sites.

If you need the TC9164 they are out there. I have just Googled it and it seems they do have the actual switches onboard.

I know that amp is considered BFC by audiophiles but that series of amps is not bad. The circutry is fine, low distortion, all that. Anything the audiophools don't hear in it is their own problem. The only problem is they are underbuilt, for someone like me. I mean I will work it into 2.3 ohms n shit, they don't like that, they get too hot. That's why I don't use one, but for normal human beings the are OK.

[jurb...@gmail.com]

>"But I'm wondering if the tape mon connections are simply labelled "in" and "out", or if they're preceded by "connect to"... "

I can't stand shit like that. Just say it, output or input, not what you connect it to.