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From: <>
Date: Sun Feb 27 13:35:59 2005

wires), so it's not suprising it goes out when the horizontal output
stage fails.

I also assume that the +53V supply (emitter of Q204) is fine when the
thing fails.

> >
> > After tracing the (good) horizontal output signal from the terminal logic
> > board into various part of the video board, and checking voltages where I
> > felt I could reach safely in a hot set, I discovered that if I shot
> > horizontal output transistor Q217 with cold spray I'd get video back right
> > away.

One problem -- on my schematic the HOT is Q214. There is no Q217.

> 2) The load is too heavy. This could be the flyback (but I doubt it -- a
> shorted turn in the flyback is going to have more serious effects that
> this), it could be something powered from the flyback (again unlikely)

Check the diodes (D207-D211) on the output side of the flyback, and the
associated caps.

> 3) The drive waveform is wrong. I don't have the H89 schematics to hand,
> but there's often a low-value electrolytic capacitor (a few uF) in the

There is,. It's C226 (10uf) on my schematic. Also check R254 (1.2R), R255
(100R) and L202 (a small coil).

Received on Sun Feb 27 2005 - 13:35:59 GMT

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