Burned Yamaha B-6

Dominic N

New Member
So I have bought something nice to restore again a Yamaha B-6 that has been on fire the inside smells terrible.
The capacitor that should have been replaced in the recall on all 220v models has caught fire and damaged the print.image-03-11-2018_17-12-46.jpgDSC_0054.JPG
 
So I have bought something nice to restore again a Yamaha B-6 that has been on fire the inside smells terrible
Oh boy. Hope you didn't pay a whole lot. Not looking good. Post photos after you get all that soot cleaned up. Output transistors should still be good. They're getting hard to find nowadays.
 
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I have seen some of the 120VAC models burn the RIFA " across the line" caps. On M-50 and M-70 amplifiers.
 
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Man those caps are bad news. I was watching a guy work on an old Macintosh computer the other day and smoke started pouring out of the case. Opened it up, Rifa cap cracked in half.
 
It is the rifa capacitor that was completely exploded and left a lot of firetracks, it is not my first amplifier that I repair but my first B-6 I now have solder all the print tracks for strength and in the meantime clean the print with some oven cleaner and let some glue flow here and there to give the print some strength again.
There has also been someone for me who has ventured an attempt, there is also a resistance of 33k 2 watt missing.

a new fuse holder, resistors and capacitors soldered and this is the result, not new but working fine again.

Now just clean the amplifier board and replace 2 wrong transistors in the power control.sketch-1542436244179.png sketch-1542436321186.pngsketch-1542436244179.png sketch-1542436321186.png
 
yes I actually also want to have mkp but I did not have that in stock, so now these capacitors are in it.

is it a bad choice?
 
C401-403 VAC rated. I'd hold out for the MKP. C404 should be X2 rated.MKP ( across the line)
Don't need any more fireworks.:D
These are all annotated in the parts list as safety items. ( * )
 
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Aha okay I did not know, I have to replace it for the right one.
Yes the positive thing is ..... in any case, he plays again.

It has to be adjusted for a while but the test points on the service manual do not seem to be right.
 
It is the rifa capacitor that was completely exploded and left a lot of firetracks, it is not my first amplifier that I repair but my first B-6 I now have solder all the print tracks for strength and in the meantime clean the print with some oven cleaner and let some glue flow here and there to give the print some strength again.
There has also been someone for me who has ventured an attempt, there is also a resistance of 33k 2 watt missing.

a new fuse holder, resistors and capacitors soldered and this is the result, not new but working fine again.

Now just clean the amplifier board and replace 2 wrong transistors in the power control.View attachment 1332568 View attachment 1332570View attachment 1332568 View attachment 1332570

wait, what???
you are keeping the board ???

ya know carbon coducts electron juice, right?
 
Yes I know, i scrubbed with sandpaper and cleaned it 5 times with an oven cleaner, there is no residue left, just soot.
The print is good to go.

There was also a lot of the burnt capacitor on the main board, and this has also been cleaned with oven cleaner.
 
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