Blues Junior trace be gone

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I've had to drill out bc sections of fried boards.

After cleaning check for any stray resistance before coating in your substance of choice.

How can I check for stray resistance ?? Do you mean make sure there are no connections from the burnt traces to other traces that shouldn't intersect ??

[olddawg]

I’ve used 5 minute epoxy. Quick, strong and available. Also replace the traces with wires from the nearest component leads. You can secure the wires in the epoxy. In really bad situations where you have to grind out a larger area of board, you can epoxy a piece of scrap board over the hole and cross it with jumpers.

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Need bias help ! I've repaired the burn, replaced D12 just as a precaution , powered it up on a limiter no adverse reaction, powered up without limiter all seems good , have sound no annoying hums . I'm a bit confused on the bias , following the steps from dadroadie thread Blues junior power tube bias . I'm getting these results

R1 = 98.8
R2 = 98.8
V1 = 10.25vdc
V2= 2.870vdc

10.25 / 98.8 = .10 x 1000 = 100 ???
2.870 / 98.8 = .03 x 1000 = 30
This is a blues junior III
Fender-Blues-Junior-III-Schematic-Rev-D.pdf

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Replaced V5 with a known good tube , calmed to 3.2vdc for V1 . So a new set of matched EL84's is recommended , now to try Leo_Gnardo bias mod on R52 correct ??

[g1]

Please provide links for "dadroadie thread Blues junior power tube bias" and "Leo_Gnardo bias mod on R52".

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https://music-electronics-forum.com/...t=blues+junior

[g1]

When you were getting that 10V reading for the one power tube, did you try swapping them around just to be sure? It may have been the funny oscillation problem (from the meter probes) so it's worth double checking in both spots before you toss it.

Yes, on to Leo's bias mod in series with R52.

[shortcircuit]

When you were getting that 10V reading for the one power tube, did you try swapping them around just to be sure? It may have been the funny oscillation problem (from the meter probes) so it's worth double checking in both spots before you toss it.

Yes, on to Leo's bias mod in series with R52.

Thanks g1 , I didn't swap it over , I was suspect that it was part of the cause of the trace burn, along with cracked solder joints on the socket , and didn't want to burn the V4 trace. But it didn't burn the repair , and it did test good on my vintage Knight tester. I'll swap and see ,might save a few $$ , that's always a good thing
PS swapped them around , shut it down when it got over 5vdc , bad tube , worth a try thanks !!

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This sways a bit off topic , installed 10k trim pot for bias ,a thanks goes out to Leo_Gnardo , it's a bit ugly.

I put a toothpick along side of R51 and folded the trim pot over and hot glued it, the pic looks like it's right on top of R51 ,there is a nice gap ,and it's quite secure , and R52 is now a true 22k . Until the new El84's arrive
Still kick myself in the a** for not doing this when I had the board pulled.
Thanks All !!!