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Old 09-26-2020, 08:30 PM   #3
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Default Re: troubleshooting definitive technology prosub 60

Originally Posted by R_J View Post
If Q1 & Q7 were shorted and R19 open, it is very likely the gate drive circuit is also damaged, Z1, Z4, R1, R18, Q3, Q4, Q5 etc. Z1&z4 are zener diodes and may check like a diode but zener at the wrong voltage.
If Q1 or Q7 shorts drain to gate, it applies 170vdc to the gate components, so it may have damaged U3d as well
Thanks BadCaps. The new Q1 and Q7 are shorted source to gate. All pins were shorted on the ones I took out. I did replace U3d and more zener diodes are on order. I will check Q3, Q4, and Q5.
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