curious symptom old Fisher stereo amp, inputs strange

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.

Reply to
Michael A. Terrell
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** Nope.

.... Phil

Reply to
Phil Allison

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.

Reply to
Tim R

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.

Reply to
thekmanrocks

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.

Reply to
dansabrservices
5:36 snipped-for-privacy@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.

Reply to
thekmanrocks

I won't argue your results, but with 35 years of repairing audio gear, I ha ve not seen one yet that has that property. The in/out label on any gear i s usually for that particular unit. The same exists on tape machines. The re 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.

Reply to
dansabrservices

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

e:

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. T here are input and output jacks there as well. The "output" jack on the ta pe 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 everythi ng, 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 m any stereos, and this includes many vintage vacuum tube Scotts, Fishers, Ei cos etc. from the 60s through the current HT surround receivers. But I'll never say never.

Reply to
John-Del

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

Reply to
Terry Schwartz

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"...

Reply to
John-Del

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 alw ays 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 si gnal backwards.

*Phono inputs are of course preamplified first.

NT

Reply to
tabbypurr

snipped-for-privacy@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.

Reply to
thekmanrocks

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

Reply to
Chuck

On Wednesday, January 9, 2019 at 3:30:16 PM UTC-5, snipped-for-privacy@gmail.com wrot e:

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 m eans the examples you cite are aberrations or at least a very small percent age of the units in service. They could have been wired that way intention ally or maybe the jacks or TM switch were miswired. It's also possible th e 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 so me low end packaged component systems that did not use universal nomenclatu re, but had connection "instructions" on the back panel (ie: connect to tap e deck output).

Reply to
John-Del

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.

Reply to
Tim R

ch jack) disconnects speakers automatically. There's no way to have both r oom 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 turn ed 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 jac k does not short, then no sound. Rare, but I have seen it a number of time s over the years.

Reply to
dansabrservices

Tim R:

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

Reply to
thekmanrocks

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

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 wor k 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 p laces.

Reply to
Tim R

te:

is in or out. I've never put speakers on B so I've not tested that set.

t plus headphones. That seems curious to me. My other stereo amps don't w ork 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.

Reply to
John-Del

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.

Reply to
thekmanrocks

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