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Fisher 500-tx, recap?

R

RaVeN38571

New Member
I found me a Fisher 500-tx tune o matic for $15 the other day. Qutie a few of the caps in it are leaking. Is it worth the money for me to recap, or should I put it on the auction site. I can do the recapping myself, just don't want to waste my money if its not worth fixing.
 
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Since this is a question about a specific model, moved to the Fisher Forum.

To answer your question, it is absolutely worth it to recap a 500-TX. This is a very nice receiver.

As a caution, questions of value are restricted to the Dollars & Sense Forum only, and mentioning selling is forbidden everywhere.
 
Absolutely Worth it. If you can figure it out , you can also make a remote control for the AUTOSCAN. It's NOT a hard Unit to Recap. With the individual boards, you can do it one at a time power up after each board, test and go on to the next.

Recommend you DO NOT mess with the AM and FM IF and Multiplex board. You can recap the Autoscan board but don't adjust the pots on it or mess with them. Lock them down with some Nail polish. You'll throw off the tuning. There is an adjustment for the AUTOSCAN board, IF you have the Service Manual.

There are some Tantalum caps on the "Equalizer amp board" that must be replaced along with the two or three on the Filter switch board. Film caps or small electrolytics are fine.

Larry
 
I made a cap replacement list today. May order some next week. I'm doing only the electrolytics, starting with the power supply. I have alot of hum in one channel, but everything else seems to work, i.e. auto tuner etc.
 
Tantalums have an explosive tendency. When they DO work, they work well. however as old as they are, an electrolytic will be a better choice plus it would sound a bit better. A poly(stacked film) would work better than an electrolytic as long as you dont have space constraints where the tantalum is. IIRC the Tant's are crowded on the Equalizer board so lytics are good choice here. On the switch board there is a bit more room for a film.

Larry
 
I think I'm going to need a little help on this one. Seems I'm not the first person to be inside this thing. Look at at the power supple it looks like someone replaced a few resistors and a zener diode. There is a spot that looks to have had a resistor but they removed it. I'm posting a couple of pics and if someone could, can they tell me if I need to change anything?

http://www.flickr.com/photos/krisandalex/5396115523

http://www.flickr.com/photos/krisandalex/5397274930/

http://www.flickr.com/photos/krisandalex/5396117095/
 
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Compare it with mine. this one has been recapped. Whoever did the repairs to yours did a shitty job. electrically it'll work, but cosmetically and strength wise it's cheesy.

The values on the resistors look ok. The "missing" resistor is also missing on mine, and the schematic shows it open on the board. HOWEVER!!!! Look just to the right of the MAIN TRANSFORMER, and you'll find the "missing resistor. They moved it from the board to keep from burning up the board.

If you want to clean it up, remove the resistors and the diode from the "joints" remove the stubs thru the holes in the board and solder in the resistors and diode directly to the traces on the board.

Larry
 
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I will definitely redo the resistors when I recap the board. What do you think of the diode, is it correct? I can't find anything from the numbers on it 1R RI70. Where can I get a schematic for the board. Thanks for all the help, I appreciate it.
 
Rick Stout @ www.stereomanuals.com has the owners and Service Manual. there is a Service Bulletin about changing the fuses around on the output transistors, that you need to check on.


The Zener is a 15Volt 3W. If it's working now, just remount it. Same with the Resistors. They don't need to be that high off the board. The previous guy was just flat out LAZY!!

I've got to look at mine. the Tuner isn't working in AM OR FM on Regular mode (lot of static and a Zero Beat around 97mHz), but the presets and AutoScan are working fine.
Larry
 
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Not normally, but Rick has a copy he'll put in the manual.

If not let me know and I'll send a copy of it.

Larry
 
I have a scan of the service manual handy. It's too big to post, but pm me your email address and I'll send it to you.
 
I got the service manual, and it's been a lot of help. Thanks Fisherdude. Larryderouin, do you think I can get a copy of the service bulletin from you? I would be grateful. Thanks.
 
Here's the Bulletin. The basic jist is, jumper the fuses on the emitter lead of each output transistor. Then add 2 fuses to the main power supply. You'll need 2 sets of PC Board mount (soldered) clips and 2 fuses (125V-5.0A Slo-Blo). The mounts will go in the F971 and F972 positions


Those big caps on the board(C975/976) have to be changed. They are both bulging. You won't find any with a stabilizer pin on the top of the casing. So just use a Radial cap(I used 2200uf/63V), insert the pins with it lying down to get the correct length. Pull it out enough to put some hot glue down and set it. Then solder the leads to the board.

C974 I used a 560uf/100V radial. I'd recommend using an axial for mounting.
 

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