Re: 454 fireworks

Sean Turner

OK, I have the scope on the bench again for a closer look at all the components in the +75 supply. Obviously I haven't torn it apart to test out of circuit, but now that I tested it again, Q1197 seems to have an emitter-collector short. I don't *think* this would result from how it is connected. Am I missing something?

Looking at the mechanical bits, it looks to me like the power transformer has to be undone to get to nuts that hold the metal part that the pass transistors heat sink to.


On Mon, Mar 15, 2021 at 03:43 PM, John wrote:

Sean: If Q1197 isn't s/c it's 99% likely the drive circuitry, which at least
is accessible!

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