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Nakamichi PA-7II won't power on, limiter resistor blown
Nakamichi PA-7II won't power on, limiter resistor blown
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Old Today, 12:00 AM   #81
Chamberman is offline Chamberman  United States
diyAudio Member
Join Date: Jun 2001
Location: USA, Dallas/Ft Worth, Tx
Sorry I should've been more specific on this test. Leave Q116 - Q119 out and power the amp up via DBT. Then measure the voltage on the incoming traces to the bases of Q117 & Q116 to see if the full neg rail is still present. This will isolate the output from the input circuitry and will point to whether the issue is up front or in the back half of the amp.

You'll have to first find the source of the short on B to C of the right ch Q117, 119 though. Perhaps and errant solder splash.

A base to collector short on those would certainly put full neg rail in the wrong place.

You may want to lift one side of R125R to see if it measures properly too.
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