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What he said was replace R43, leave C37 and V5 tube out for now. Try it without them to see if R43 still overheats.
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"Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey -
I appreciate the help. I'll get back once I get it delivered and installed. ThanksComment
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I did have a bluesman in for repair with a similar issue. The issue was caused by a bent pin on the phase splitter valve base, somehow the customer managed to bent pin 1 and it shorted to the chassis!
Look for the easiest and most obvious.
Just as a test, fit a 10k or something near value. When fixed, use the correct value of course but any reasonable value will allow you to progress.
Thanks for the help on my dyslexic writing G1. Appreciated.
Edited to include more information and a suggestion.Support for Fender, Marshall, Mesa, VOX and many more. https://jonsnell.co.ukComment
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I don't have any resistors any where close to that one, so I'll have to wait till one gets delivered. Thanks for your help.Comment
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Installed new R43, removed C37 & V5 preamp tube. Variac @ 60v reading 242v on both ends of R43. Should I go to 100v on variac to see if R43 burns? Have two(2) more if it does. If I remember right, this us the first time i've gotten same reading on both ends of R43, even though C37 seems to be good(charges to OL, then discharges on dcv).Comment
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If the resistor has virtually no voltage drop, you are probably good to raise the voltage. I usually monitor current as I bring up the voltage so that you can see if something suddenly starts to draw excessive current. If you have a current meter, put it in line with the variac. Your meter doesn't test caps at rated voltage, so they can test good on a DVM, but fail under higher voltage differential."Yeah, well, you know, that's just, like, your opinion, man."Comment
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Now getting 383v @ R43 on both ends, no smoke or smell of epoxy melting.Comment
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Should I try installing V5 now with C37 still out and go to 100v?Comment
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Yes. It's ok to test with C37 removed."Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick BaileyComment
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Ok, tested with V5 installed. Getting 370vdc @ 100 v on variac both sides of R43. Have new C37. Any suggestions before I install and test?Comment
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Just make sure you install it with correct polarity.
"Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick BaileyComment
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Appreciate all your help. Thanks.Comment
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Ok, installed C37 and at 60v on variac R52 is burnt .Originally posted by g1 View PostJust make sure you install it with correct polarity.Comment
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I see an R52 connected to the hum balance pot. Did you see it burn or could it have burnt before? Doesn't seem to be anything that would be related to C37.
Are power tubes installed? Any chance one of them has the locater pin broken off in the center of the base of the tube?"Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick BaileyComment
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I actually saw what looked like the size of a cap light up when I turned it on. C2/C7 area of board. I've checked both el34s and they both have the locater pin glued back on.Originally posted by g1 View PostComment
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