Kimo Chun wrote:
>Mike,
>
>
>
>Did you get your problem fixed? I am not a subscriber to the list but just
>happened across the thread...
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>
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>
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>Kimo KH7U
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>
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>I am about to pull my Alpha 91B out of the operating desk to do a post
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>mortem. The amp has AC power and the 4 fuses on the rear apron appear
>
>good (buzzed them out with my Fluke meter), but nothing happens when I
>
>push the on/off rocker switch (not even a single flash from any of the
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>LEDs). Any idea where I should look first for a problem.
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>
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>Thanks,
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>
>
>Mike W4EF........
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>
I am embarassed to admit, but I just got after it this evening, Kimo.
I've had a bunch of other things going on, so I just kept putting it off
- that is - until my backup amp died last night (looks like something
arced over on the high voltage rectifier board). I figured that was the
signal that I needed to start troubleshooting the primary amp :-) :-).
The problem looks like a 1K ohm x 10 watt resistor R2 on the "MAINS
BOARD" PCB. It reads on open circuit on my DVM. I think this would be
consistent with the observed symptoms. In the troubleshooting section of
the manual under "91B will not turn on; nothing happens when ON switch
is pushed", the manual says "Step-start resistor R6 or R7 open". I don't
see an R7 on the mains board, but this may be a typo. With R2 open, I
don't see how K1 could energize.
The front-panel rocker switch that some suggested might be the culprit
checks out okay with the DVM.
73, Mike W4EF
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