high pitch squealing out of right channel after restore kit installed

M

Mike Wehner

New Member
Well I just finished installing the metalbone kit on my fisher 800c. It was pretty straightforward however after intial start up im getting high pitch loud squeal out of right channel. Any idea where to start? There was no smoke odd smells or pops. It does play music however sounds a bit muddled. I did not let it warm up as the sound was un bearable can that be done in the off position? Any advice in a basic format would be extremely helpful as I'm a total newbie. Thanks in advance,

Mike
 
Did you happen to remove the transformer leads from the output tube sockets on the affected side? If so there is a distinct possibility that the leads were put back on reversed.
 
This happened to me. I rechecked my work and found I had connected a new cap wrong

In my instance it was a cap from one pin of the output tube. I connected one end to the wrong lead on a terminal strip

fixed it and it was fine

What I do is, when I cut out the old cap I leave 3/8" of the old lead to attach the new cap to. Then if I look away I can always find the cut lead for the new cap

cuts down on errors

good luck
 
Thanks I will double check my work tomorrow. I have a feeling it may be something simple like that but was so disappointed after all of that work.If it was easy everybody would do it.
 
The good news is that you can use the left channel in the power amp section to compare to the right to see if anything is installed wrongly on. Double check the wires from the speaker output jack to see where each goes because they may have reversed the left and right output tube pairs compared to what speaker they go to. My Fisher 400 is like this and same with my Eico st70.

We've all been where you're at. If you get stuck post some good pictures of your work and maybe one of us can spot what went wrong.

Dan
 
Agree with DannyR on the pics. Post them up ASAP, and while you are looking one or two of us will be looking also.

Larry
 
pics of output capacitors

I think that I may have soldered the capacitor on the wrong tab. I marked it with the alligator clip. Does that seem right?
 

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this was an area that left me scratching my head a bit

The purple wire I had to read the instructions over and over.
 

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Correct! The cap with the clip on it should have its lead moved one terminal to the left (on pin #1 of the tube socket). By have this cap connected to pin #2 as you do, it has reversed the phase of the signal sent to one of the output tubes -- and in doing so, has reversed the phase of a portion of the negative feedback signal, so that it has now become (in part) a positive feedback signal, causing the squealing noise you hear.

No damage was likely done, but do check the tweeter in the speaker that was connected to this channel. High power high frequency oscillation can do damage to them. If it still works, then all is good. Make your connections good, and enjoy!

Dave
 
We'll need a wider shot to see what the purple wire is, where it goes, etc. It appears to be supplying bias to the output tubes, but a better shot will help to confirm this.

Dave
 
news flash! I soldered sonic to wrong tab on v15 corrected and works ! Nice and quiet at idle with out warm up! I have it hooked up to my B&W 602's. I cant wait to here it through my pinnacle gold reference speakers as they are more efficient. On my way to get the dental tool to clean the tube sockets to finish the rest
 
pics of output capacitors

I think that I may have soldered the capacitor on the wrong tab. I marked it with the alligator clip. Does that seem right?
 
Thanks everyone for their help and encouragement as it sounds awesome! I almost gave up.I'm home from work with an injured back and I sold my former main system marantz 2275 to fund the restoration parts and tools. My home is now filled with music again and I am very happy.
 
pics of output capacitors

I think that I may have soldered the capacitor on the wrong tab. I marked it with the alligator clip. Does that seem right?
 
dcgillespie said:
Not sure what's going on with the triple posting of the previous post......

Dave
Click to expand...

Dave: I think it means that his computer is as happy as he is and it's stuttering with joy. When that joy enters the digital domain, it ends up as multiple posts.

I read the explanation on the internet, so you know. :D
 
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