Originally posted by drewl
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Blues Junior trace be gone
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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.pdfLast edited by shortcircuit; 07-12-2019, 07:38 PM.If you don't know where your going any road'll take you there : George Harrison
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Please provide links for "dadroadie thread Blues junior power tube bias" and "Leo_Gnardo bias mod on R52".Originally posted by EnzoI have a sign in my shop that says, "Never think up reasons not to check something."
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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.Originally posted by EnzoI have a sign in my shop that says, "Never think up reasons not to check something."
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Originally posted by g1 View PostWhen 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.
PS swapped them around , shut it down when it got over 5vdc , bad tube , worth a try thanks !!Last edited by shortcircuit; 07-13-2019, 12:34 PM.If you don't know where your going any road'll take you there : George Harrison
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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 !!!If you don't know where your going any road'll take you there : George Harrison
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