Earlly (ca 1971-74) Fisher Quad Receivers--share what you love/know about 'em!

[larryderouin]

1st thing I'd do is make sure the Switches and pots on the front panel and on the back panel (if it has them on back) are cleaned with DeOxit D-5 then lubed with DeOxit F5 Faderlube. 2nd, make sure the POWER SUPPLY is putting out the correct voltages per the schematic. Then after determining that the voltages are ok (either the board is ok, or it needs work) check voltages on the Tuner board(s). Repair all problems. Then do a recap of the whole thing, as the casp are way past their life cycle time (about 20 years ). Repairs could be as simple as a transistor or 3, or some caps. In any event repair the problems and then update/upgrade all electrolytic caps and some of the film caps.

Manual is at HIFIENGINE.COM . Registration is required but free. Link to manual https://www.hifiengine.com/manual_library/fisher/495.shtml

 

[MJ1951]

Thanks for the reply. I printed the manual from hifiengine and will do the DeOxit cleaning again.

 

[MJ1951]

1st thing I'd do is make sure the Switches and pots on the front panel and on the back panel (if it has them on back) are cleaned with DeOxit D-5 then lubed with DeOxit F5 Faderlube. 2nd, make sure the POWER SUPPLY is putting out the correct voltages per the schematic. Then after determining that the voltages are ok (either the board is ok, or it needs work) check voltages on the Tuner board(s). Repair all problems. Then do a recap of the whole thing, as the casp are way past their life cycle time (about 20 years ). Repairs could be as simple as a transistor or 3, or some caps. In any event repair the problems and then update/upgrade all electrolytic caps and some of the film caps.

Manual is at HIFIENGINE.COM . Registration is required but free. Link to manual https://www.hifiengine.com/manual_library/fisher/495.shtml

OK - Checked the power supply voltages and other test points and they are in the ball park. Replaced all of the electrolytics as recommended (maybe just for the adventure of it as it turns out).
It looks like the real the problem may be an op amp on the tuner board. The chip acts as the FM stereo channel splitter and "stereo beacon" indicator. The "stereo beacon" pin is not pulling to ground to turn on the light. There is 12 volts on the other side of the lamp so this side would have to be pulled to ground. And the FM audio is low as though the chip should be providing some amplification.
I cannot find a spec sheet for the IC. The IC is identified on the schematic as "Integrated Circuit, MPX, HA1115W". Does it sound likely that the IC has gone bad? Anyone know what could be used as a substitution?

 

[fred soop]

That IC part number is most likely a "house number". There were several chips in common use, so you might look at several and try to determine if the connections to the various pins make sense. For example, maybe pins 4-5 are audio out on one chip while pins 12-13 are audio out on another.

 

[MJ1951]

In searching for that part number I ran across a pdf of the 'IC Master Reference 1977'. It does list the part under Hitachi an does have a substitute TI part of SN76105N. I can't find a spec sheet for the TI part on the web either.
There are some old Hitachi Semiconductor web pages that come up and list the HA1115W part but links under the page are broken. Sure would like to have confirmation that the chip is supposed to work the way that I think it is supposed to work.
There is a guy on ebay that has a couple of SN76105N - may have to spend the bucks just to test my theory that this HA1115W is bad.
Still hoping to hear that someone else has seen this problem.

 

[fred soop]

Found it here. It is a typical multiplex decoder that could be replaced with LM1800, LM1870, or MC1307. Any of those might also be hard to find today but they do show up once in a while. You would need to modify the circuit board to accommodate a different pin layout. That would be most easily accomplished by making a small board, just large enough for the chip (and possibly some related parts) with short leads to connect to the original position. Of course, you would want to breadboard and test before doing a lot of detailed work.

https://www.radiomuseum.org/tubes/tube_sn76105.html

 

[larryderouin]

NTE is still showing NTE722 as a sub for the MC1307. And there is a pinout on the sheet for the 722.

 

[MJ1951]

Very helpful. Glad to see something about the sn76105. I may go ahead with that part. Is there much more that is available from that radiomuseum web site if i sign up on it? Gives me the feeling that it is for "click bait".

The NTE722 is available from Amazon but it looks like the B+ is on a different pin, and it looks like it does not support the "tuning mute".

 

[fred soop]

I've never signed up for RadioMuseum but have found a lot of good information without having an account.

 

[LanceBroyles]

Hello all! I have acquired a Fisher 434 it is one of the Models that has the NY Address listed. I cannot get this thing to turn on. I have checked all fuses, I’m getting voltage in so power cable isn’t bad. But nothing works from there. I am trying to find a recap kit or just even the caps themselves and am having a very difficult time. I’ve found the Electrolytical Caps pretty easily but the others I am not sure where to look or what even some of them are called. The inside of this Radio looks immaculate as well as the outside, so I am really anxious to get this thing up and running but I am having no luck what so ever. I went to the extent of replacing the Big Can Capacitors hoping that might would do the trick but no dice. If anyone could offer some help or assistance or recommendations I would greatly appreciate it very much! I feel like if I can just get this power supply rebuilt I might be in good shape hopefully.

Thanks in Advance!

 

[larryderouin]

Meter the power switch for continuity to make sure it works. If it does, check the line to the transformer and see if it has a fuse inline. Meter it for continuity. Then meter the primary and secondary sides of the transformer for continuity, it's possible the transformer could be open in the primary (slight at this point, I'd vote more for a bad switch or a fuse at this point.).

 

[TonyCos]

Hi-
Love this site - I have lurked here for ages, just never posted. I have a lovely Fisher 634 quad that my father purchased new in '76, and I have been lovingly using since '88. I'm not sure what it is about it, but it just sounds rich and smooth. I have other high-end Yamaha gear, as well as Marantz SS units, but this Fisher is different. Over the years I've had to do very little to it besides using some contact cleaner on the switches and dials. This weekend however, I turned it on, and immediately heard a soft-ish, bassy crackle/boom/pop through the speakers on power-up. No smoke, no burned traces inside, and the only thing that now works is the backlighting. No output whatsoever on any channel, nor through the headphone out, no tuner response. I checked all fuses, and all have continuity. With everything dead except the lighting, I'm thinking it has to be something early in the power circuit, correct? Does this issue sound familiar to anyone, or can someone kindly give me an idea of what to look at / test first?

Thank you!

 

[larryderouin]

Tony: I've got the SEARS Version from 1978 on the "to do" list. Nice sounding but tired.
How familiar are you with reading a schematic? Do you have the Service Manual? If not it's on HIFIENGINE.com Mandatory registration, but free. NO SPAM.
https://www.hifiengine.com/manual_library/fisher/634.shtml

This is the power supply area for the 634. One 6A 250V SLO BLOW on the back bulkhead. If that blew you wouldn't have lights either. 2 are on the Fuse board. 10A 250V Slow Blow. And a final .75A (3/4A) 250V inline on the POWER SUPPLY BOARD! At least one of these probably blew. Pull them out and test again with the ohm meter. NOTE Voltage and AMPS on all 3 fuses. They could be the WRONG Values,(hey it's possible Slow blow can sound like a crackle/sizzle/pop when it goes, but you said you heard it thru your speakers. Which leads us to possibly Capacitors, drivers and output transistors. Good possibility that one or more shorted (output's) or drivers are shorted. They have to be tested. https://audiokarma.org/forums/index.php?threads/bipolar-junction-transistor-testing-basics.43186/

Look at the tops of all the caps on the POWER SUPPLY, Protection board, AMPLIFIER BOARDS, and the rest of them for good measure. If any are split at the top or obviously bulged on the top, bottom, or Sides, replace. Right now we're going to try to get it running enough so that it's stable. Then you might as well plan on a detailed restoration. 43 year old electrolytics are pretty well dried out, even Nichicons's. Dried out caps short and cause plenty of problems.

DO NOT PLUG IT IN AGAIN unless advised to do so. Do you have the skills to Build a DBT(Dim Bulb Tester)? Any more power up's will be with the DBT online btwn the wall socket and the unit. This will mitigate further damage to the unit by taking the load by lighting up if the unit has a short.

In the Search box here or on Google, search DIM BULB TESTER. There are block diagrams to build one. Probably about $15 in parts from Home Depot or Lowes. You'll need a 60W, 75W, and 100W INCANDESCENT BULBS. NO Florescent or LED's. INCANDESCENT. A 3way 50-100-150 is fine as long as you install a 3way socket on the DBT.

If you feel that this is above your paygrade (and it's above mine, I hate working on Solid State, but it's a FISHER. My T/S skills are basic when it comes to S.S. as I'm more comfortable with Tubes.) Stop at the fuses and get it to a shop. There are guys on AK that do work on gear, and if you put feelers out in the "DOLLARS and SENSE" forum you might get one of them to at least look at it. Putting your location in your profile (county and state is close enough) helps us to determine who's close enough to you to maybe get you some face time.

Larry

 

[TonyCos]

Hi Larry -
Thank you so much for your detailed reply. Yes, if I could just get it back working and stable, I can do a full restoration. It would appear that it needs it!
I am reasonably good with a schematic, and have just downloaded it - thank you for the link! I have built many electronics projects - guitar effects pedals, done other electronics troubleshooting / simple circuit board level diagnostics, and am great with a soldering iron, but have a lot to learn. I've wired entire houses, so the dim bulb tester would be a very easy build for me. I can make one up later tonight/tomorrow. I have never tested a diode nor transistor, so will research that.

All the fuses test fine, and all are the correct values. No caps on any boards - power supply, amplifier board, nor any others show signs of splits nor bulges. I am familiar with what those look like when they go, so there been no obvious catastrophic failure.

It behaves almost as if the mute off switch was disengaged, but from memory, even with that off there is still a little bleed at high volume. With this - absolute silence. Typically, I'd also get a speaker burp when changing between SQ and Phase logic, for instance. Not any longer. Just backlighting!

Tony

 

[fred soop]

Start with the power supplies. If you have low or no voltage, then the problem is between the point of measurement and the AC line. If voltages are ok, then the problem is downstream. You can't test anything else properly unless the power supply is good.

 

[TonyCos]

Wanted to say thank you - everything is now working. After studying the schematic, testing the power transformer, and conducting other tests, what I was experiencing seemed to be a poorly seated molex connector making intermittent contact. I had reseated all of them on my initial inspection before my first post, but apparently didn't do a good enough job. Second time was the charm! I feel a little embarrassed that this was the problem...

Thankfully this was an easy fix, and now that she's up and working again, I'm planning a clean and a recap. Lots of accumulated dust in there under the vents. Got 16x midrange to refoam (again) on my main speakers as well. Looks like a good winter project. Thank you again!

 

[larryderouin]

Don't knock yourself hard about it. We've all BTDT. So Welcome to the Club. If you learn from it, even better. Start a New thread when you do the Recap and include pictures of the insides, Before and After Pictures.

 

[TonyCos]

Cool, will do! There are so many caps in there. I believe I counted close to 40-50 on the cd-4 board, alone.
One thing I'm thinking in that regard, is that I really like the sound of the tuner section, so I will probably just leave that board as is unless they test out of spec. I'm not sure if these Fishers are particularly known for their tuner section or not, but I rather enjoy how it sounds, and wouldn't want that to change.

 

[fred soop]

Cool, will do! There are so many caps in there. I believe I counted close to 40-50 on the cd-4 board, alone.
One thing I'm thinking in that regard, is that I really like the sound of the tuner section, so I will probably just leave that board as is unless they test out of spec. I'm not sure if these Fishers are particularly known for their tuner section or not, but I rather enjoy how it sounds, and wouldn't want that to change.

The earlier Fishers were definitely noted for tuner performance. On another thread, I was mentioning the difference in actual performance of a Fisher 600-T vs a much newer, much better specs, Harman-Kardon Citation 23. The real world performance of the Citation is essentially no better, only 6 additional stations, and those are adjacent channel requiring the high selectivity mode. I mentioned that I wasn't sure if I was impressed with the Fisher or unimpressed with the HK. Someone responded that they were surprised that the HK was even that good because FM was becoming irrelevant by that time.

 

[TonyCos]

The earlier Fishers were definitely noted for tuner performance. On another thread, I was mentioning the difference in actual performance of a Fisher 600-T vs a much newer, much better specs, Harman-Kardon Citation 23. The real world performance of the Citation is essentially no better, only 6 additional stations, and those are adjacent channel requiring the high selectivity mode. I mentioned that I wasn't sure if I was impressed with the Fisher or unimpressed with the HK. Someone responded that they were surprised that the HK was even that good because FM was becoming irrelevant by that time.

As I'm looking for a nice vintage tuner for my main system, yesterday I took what I've temporarily got there - a Yamaha tx950 - and hooked it to aux input of my 634 so I could do a comparison. It was like night and day. The 634 sounded rich and full. The 950 sounded a little cleaner, but not in a good way - thin and sterile. Now, I know I've gotten used to the sound of the 634 over the years, but this was a surprising sonically driven test, not to mention that it had a far easier time pulling in stations from just a simple dipole.