Monitors

From: Joe <rigdonj_at_intellistar.net>
Date: Wed Aug 5 21:39:01 1998

Tony,

>If you can fix TVs you're over halfway to fixing monitors
>
>> it's not worth the time or parts that it would cost to fix it. Or course,
>
>Not so. Most TV faults can be fixed in under an hour using fairly cheap
>parts. About the worst thing that's likely to go is the flyback transformer.

  And the horizontal output transistor 95% of the time. Flybacks and HOTs
are very expensive here if you order a specific part. The last flyback that
I got cost $80! If you can get a generic part number then they're a lot
cheaper.
>
>Maybe I only get the higher class of TV sets here,

  They MUST be!

but I certainly find
>them worth repairing. The cheap modern crap produces a picture that IMHO
>is unwatchable even when you've tweaked all the adjustments...

  Then you should see the crap that they sell in the discount stores here!
>
>
>> >Vertical scan rates are a lot easier to modify, so those don't bother me
>> >so much.
>>
>> Have you done much of that? How successfull were you?
>
>It's _Very_ easy to modify the vertical scan rate. The horizontal scan
>system is nasty to modify because (a) the flyback is tuned to (a harmonic
>of) the scan rate, (b) the EHT voltage depends on the scan rate and (c)
>the scan sawtooth is partially produced by the inductance of the yoke. So
>changing anything there is a pain.

   How far can you shift the horizontal frequency?
>
>But the vertical system is more friendly. The sawtooth waveform is
>produced in a low-level stage, amplified by what's essentially an audio
>amplifier (in fact some TVs used an audio amplifier chip here), and sent
>to the yoke. Given a data sheet on the chip you can normally figure out
>what components to change.

   Is it just a RC circuit?

  Joe
Received on Wed Aug 05 1998 - 21:39:01 BST