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From: <bogus_at_does.not.exist.com>
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).

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