Fisher premiere/600 tube receiver help

rshadley

Active Member
I picked up a fisher premiere along with a mpx100. I was going to attempt a rebuild on my own. I checked all tubes and they are good. I used a variac to bring it up. Channel A is is working fine but channel B just has a slight hum and no music. I took the bottom plate off and I see 2 ceramic capaictors that have what appear to be a small burn mark on them. Could this be part of the problem. SEE PICS Any input thoughts would be greatly appreciated.
 

Attachments

  • Picture 2029.jpg
    Picture 2029.jpg
    89 KB · Views: 230
  • Picture 2030.jpg
    Picture 2030.jpg
    113.8 KB · Views: 70
  • Picture 2031.jpg
    Picture 2031.jpg
    74.1 KB · Views: 76
They do look a little charred.. Ceramics are usually not so much prone to fail, maybe something else they are connected to is not up to snuff.

If it were mine, I would not apply power untill after power supply and coupling caps were replaced at bare minimum and also resistors checked for wandering values.

It is a nice looking unit btw
 
attachment.php


Beautiful :thmbsp:
My favorite face plate style.


Steve
 
I'am kind of a novice at this rebuild thing. I have messed around with a few maggie amps. I would like to get the problem fixed before I start an accross the board cap replacement. It appears that those two ceramic caps are connected to ground(center post) there is one black lead that goes to the phase inverter switch. There is another black lead that goes to pin 2 of one of the 12ax7 tubes. That pin also is connected to the negative side of the large orange cap you see up front(100MFD 150 volts.) The positive side of that cap connects to the other 12ax7 pin 4. One of these 12ax7 was dead and the other was questionable. I replaced all 4 of the 12ax7's.
 
There is a copy of the schematic here on audiokarma and I do have a variac as well as a sencore capacitor checker(out of circuit) I thought I would start off by changing those two ceramics, the coupling capaciotors and the large orange capacitor and try and bring it up on the variac again.
 
it looks like the channel b runs through the phase inverter switch and the 100 mfd 150 volt capictor that is connected to the two 12ax7 tubes.
 
There is a copy of the schematic here on audiokarma and I do have a variac as well as a sencore capacitor checker(out of circuit) I thought I would start off by changing those two ceramics, the coupling capaciotors and the large orange capacitor and try and bring it up on the variac again.

that sounds like a good plan
 
Check the bottom plate for signs of arcing at the cap location. If/when you replace them locate them so they aren't near the bottom plate.

Larry
 
the only 390pf (uuf) caps in the whole enchilada are C140-141-142-143. They are connected to resistors(680K R 150-151-153-154)Blu-Gry-Yel (10K R152-155)Brn-Blk-ORG, and (1K R157-160-162-163 )Brn-Blk-Red Between the 7199 tubes and the output tubes. R150-151-153-154 are also the only 680K resistors in the unit.

It's possible that the caps have failed short and the tube isn't getting any signal.
Replace the two caps and check the surrounding resistors (out of circuit) and replace any out of spec.

Larry
 
I will be out of country for two weeks. I have the parts ordered and will change the coupling caps as well for this first phase along with the orange capacitor(100 mfd 150 volts) that I beleive is part the the phase inverter circuit. I will then bring it back up on the variac and report back. I do have resistance readings on both output transformers and when I check the resistanced between the red and blue leads of the output transformer I here noise on both speakers. I assuming that they are both good. Thanks for the input.
 
Capacitors, unless they have failed, never get hot, and ceramics rarely fail. Since you've already had it turned on, turn it back on, let it run for a few minutes, and see if they get hot. If not, those aren't burn marks.

Have you used DeOxit or a similar contact cleaner on all the switches, controls, and tube sockets and pins? If not, that's your next step.

And you do need to do coupling caps, etc., etc..
 
I used contact cleaner on the phase inverter switch, volume pot, balance pot and tape monitor switch. I did not clean the tube sockets or pins. I will try that first.
 
And thats not my handi-work that removed the volume stenciling. It came out of the console in that shape. Looks like somebody took brake cleaner to it. I did get it from the original owner though.
 
That was it. A good cleaning of the selector switches, loudness switch the 7189, 7199 and 12ax7 sockets and both channels are working. Now I can start the cap replacement little by little and bringing back up after changing only a few sections at a time. Thanks Again. I will still post updates as i go through it. maybe a few pics if there is any interest but I know Kory documented his complete rebuild. Once I tackle this I will start with my X-202B which I beleive Kory also documented. Thanks Again
 
I bought a very nice Fisher 400 off eBay not long ago. Pics were decent, but the listing said "One channel is dead". I did a little bottom fishing and got it for $122.

It arrived undamaged, and looked even better than in the pics. Fired it up, right channel dead. Unplugged it, worked all the switches and controls back and forth a few dozen times, clickety-clickety-clickety-click. Turned it back on, beautiful stereo sound from both channels.

Congrats on your gorgeous 600! :yes:
 
Back from Peru and decided to start the capacitor replacement. I have a question and hope its not to late. DO RUSSIAN K-42Y HAVE A POSITIVE OR NEGATIVE END? I should have asked the ? before I installed the .1uf 500 volt k42-y's.
 

Attachments

  • Picture 2041.jpg
    Picture 2041.jpg
    117.4 KB · Views: 28
No. They are bipolar or non directional. You are OK either way you put them in.

Larry
 
Back
Top Bottom