Hi Barry,
I think you fixed the root cause of why shorting across C-E of Q8051 didn't work. I was expecting to see the same voltage as if Q7042 was removed (+0.6V) but at this point the regulator should be able to control the voltage. Do you still see ~ -33V at the output?
Do you have the original transistors to try or was Q7042 the shorted one?
Q7042 (151-0103-00) cross references to 2n2219A, plain 2n2219 has a Vceo of 30V and lower fT than 2n2219A. This device will see Vce~ 33V in normal operation.
page 6-3 of:
Ozan
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On Mon, Dec 23, 2024 at 01:47 PM, Barry Breaux wrote:
Ozan,
I found a broken trace which I repaired.
I also swapped out a few transistors.
Today I am measuring -0.48 volts when I short across C-E of Q8051.
I understand that 2N2222A is a lower wattage equivalent to the 2N2219. I have
ordered additional 2N2219. The 2N2219 was/is shorted.
There is a .3VPP oscillation at the base of Q7042. a 50mv ripple on the +12V
and a .2V ripple on the -33.5V.
I am still plugging away at it.
Thank you!
