Re: Intermittent fault in Eizo 19" T766 CRT

Wiebe Cazemier <wiebe@xxxxxxxxxxxx> wrote in
news:fcc4$48135a13$d4cc82be$10201@xxxxxxxxxxxxxxxxxxxxxxxx:

On Saturday 26 April 2008 13:21, bz wrote:

Sounds like you might have an intermittent short to ground on a power
supply line, perhaps inside a bad capacitor.
Or an intermittent connection in the voltage sensing circuits, or the
AC line into the power supply.

The problem here is, that I'm not too familiar with CRT screen
electronics. I'm pretty well versed in audio electronics and other more
common, low voltage, stuff, but I've never really had to deal with CRTs,
so I don't know too much about them, or how to localize the circuits you
mentioned (except perhaps the PSU).

Would you happen to know of a good book/guide about CRT repair, or at
least an explanation of the insides?


Intermittents are difficult to localize and fix.

Tell me about it... This fault only happens when it's just turned on,
thus far, and very hard to reproduce.

So, what is different about 'just turned on'?
Components are cool.
High transient currents occur.

Look for places that those can make a difference.

Perhaps you can narrow down the problem by monitoring voltages at
various points while it is acting up.

I also have a transient recorder, although only a single channel. Still,
it should be useful. However, come to think of it, the voltages inside
the monitor are probably too high for it...

From the symptoms, I would start by looking at the PSU outputs.
Troubleshoot by 'divide and conquer'.

Divide the device logically into two halves, and localize the problem to
one of the two.

Continue until you reach the bad part.






--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@xxxxxxxxxxxxxxxxxxxx remove ch100-5 to avoid spam trap
.

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