Re: Space Duel HV advice

On Mon, 18 Oct 1999, Jess Askey wrote:

> Basically, if the squre wave is not making it to the main output
> transistor, then the HV transformer will not be driven with the +27V.
> The 180V supply is derived from the collapse of the magnetic field on
> the HV transformer. You don't have 180V because the HV transformer is
> not being driven (turned on and off via the square wave).

I've got a wave comming out of the 555, and on the collector of Q904.
Instead of being amplified at Q905 (the big 2N6557) however, it becomes very
small.

The schematic gives some voltages at certain nodes of the circuit, I assume
these are for troubleshooting purposes. It shows the collector of Q905 as
24.8v. I see -25v. It shows 5.9/5.4 at the base/emitter of q900 (the BU409),
I have 26v at both (same as collector). The tail end of ZD902 should have
29.4v, I again show -25.

I do see the correct -19.2v at the collector of Q904.

I replaced Q901, 902, and 903. I swapped the 2N6557 with one in another
monitor -- it was good. The BU409 and BU207 test OK.

I'm really open to suggestions at this point.

-Chris

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Chris Candreva -- chris@westnet.com -- (914) 967-7816
WestNet Internet Services of Westchester
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Received on Mon Oct 18 23:10:57 1999