Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: rat3hat on August 01, 2020, 08:19:20 AM
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Hi. I have one voltage check outside of the target range for the big board:
Targets from the manual:
OA 75-100V
OB 75-100V
G 0V
B+ 170-195V
My voltage readings:
OA 90.7V
OB 77.4V
G 0V
B+ 114.5V
B+ should be higher. It is probably the usual suspects (crappy joint somewhere), but I thought I'd ask where was likely.
Best,
Chris
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B+ connects back to terminals 2 and 4, as well as IA and IB on the big PC board.
How are the voltages on the small board? Does B+ pop back up if you run the amp without the 6080?
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Small board Measurements
OA 75V
IA 120V
B-A/B 0V
IB 120V
OB 75V
It did pass checks after mounting small board earlier
Large board without 6080 B+ is 225V
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Also, perhaps the heat sink closer to the 6080 is hotter than the heat sink closer to the 12au7 socket. Not sure if this means anything.
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Are the TIP50 transistors properly mounted? Be sure B+ to the big board is not connected to terminal 2 or 4 by accident.
If all else fails, you can post photos of the build and we might be able to spot something.
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OK. My 15 y/o was sharp enough to point out that I was missing an LED on the big board at D2.... :o >:(
Once I put that in, it all seems to be measuring in range. On the big board OA, OB are measuring ~110V each. That is around 10% above the high - I am assuming that is OK - or is that just too high?
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Yes, that's OK.
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Thank you, again - for being a patient and excellent guide. Great kit.