curious symptom old Fisher stereo amp, inputs strange

[Michael A. Terrell]

jurb6006@gmail.com wrote:

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.

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.

 

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.

 

On Tuesday, January 8, 2019 at 5:34:00 PM UTC-5, thekma...@gmail.com wrote:

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.

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.

 

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.

 

On Tuesday, January 8, 2019 at 6:07:32 PM UTC-5, thekma...@gmail.com wrote:

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.

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]

On Tuesday, January 8, 2019 at 7:36:01 PM UTC-5, dansabr...@yahoo.com wrote:

On Tuesday, January 8, 2019 at 6:07:32 PM UTC-5, thekma...@gmail.com wrote:
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.

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.

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]

On Tuesday, January 8, 2019 at 4:34:00 PM UTC-6, thekma...@gmail.com wrote:

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.

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

 

[John-Del]

On Tuesday, January 8, 2019 at 8:11:28 PM UTC-5, Terry Schwartz wrote:

On Tuesday, January 8, 2019 at 4:34:00 PM UTC-6, thekma...@gmail.com wrote:
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.

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

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"...

 

On Tuesday, 8 January 2019 22:34:00 UTC, thekma...@gmail.com wrote:

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.

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

 

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), dansabrservices@yahoo.com
wrote:

On Tuesday, January 8, 2019 at 6:07:32 PM UTC-5, thekma...@gmail.com wrote:
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.

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

 

[John-Del]

On Wednesday, January 9, 2019 at 3:30:16 PM UTC-5, thekma...@gmail.com wrote:

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.

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.

 

On Friday, January 11, 2019 at 9:26:30 AM UTC-5, Tim R wrote:

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.

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.

 

Tim R:

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

 

[Tim R]

On Friday, January 11, 2019 at 12:45:21 PM UTC-5, thekma...@gmail.com wrote:

Tim R:

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

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]

On Sunday, January 13, 2019 at 7:09:40 AM UTC-5, Tim R wrote:

On Friday, January 11, 2019 at 12:45:21 PM UTC-5, thekma...@gmail.com wrote:
Tim R:

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

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.

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.

 

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.