Hi All,
I was working on the Power Amp board of my Sunn Beta lead to find out why the -15vdc supply was only reading -13vdc.
Wondering whether IC-1 might be partially shorted and dragging down the voltage, I pulled it from its socket (see attached schematic) so I could power on the amp for 2 seconds and take a voltage measurement. To me, judging by the schematic, this seemed like a harmless enough move (note: I'm not an advanced tech, maybe a step above a novice).
Well, the second I turned the amp on to take the measurement, I got a horrendous hum from the speaker. I powered down and found Q19 blown.
My question is . . . why? What did removing IC-1 do to the circuit that caused the output transistor to short out? To me, IC-1 seems to be taking inputs for monitoring purposes only.
Thoughts?
Any thoughts/input/ideas appreciated,
Bud
I was working on the Power Amp board of my Sunn Beta lead to find out why the -15vdc supply was only reading -13vdc.
Wondering whether IC-1 might be partially shorted and dragging down the voltage, I pulled it from its socket (see attached schematic) so I could power on the amp for 2 seconds and take a voltage measurement. To me, judging by the schematic, this seemed like a harmless enough move (note: I'm not an advanced tech, maybe a step above a novice).
Well, the second I turned the amp on to take the measurement, I got a horrendous hum from the speaker. I powered down and found Q19 blown.
My question is . . . why? What did removing IC-1 do to the circuit that caused the output transistor to short out? To me, IC-1 seems to be taking inputs for monitoring purposes only.
Thoughts?
Any thoughts/input/ideas appreciated,
Bud