high voltage regulation in monitor

[Reinhard]

I got a ibm 6547 monitor which flickers when started up also the brightness seems to high.
When put in a high resolution mode it stops flickering. Adjusting the screen voltage on
the flyback has the same effect. My guess is then that there is a problem in the HV
regulation. I checked the supply voltages to be ok. Since it is probably a component which
has run out of its specs instead of being broken it is a bit hard for a novice like me to
find that component.

I found the schematic (a Samsung CKB chassis) on:
http://www.promelec.ru/scheme/CKB5237.pdf

Could someone give me a few hints?



Thanks,

Reinhard



P.S. Just to check my understanding of the faqs: am I correct in stating that this chassis
uses a separate transistor, Q503, for the high voltage creation. And the HOT, Q406, is her
just for the deflection part?

 

[Jerry G.]

The fault can be in the high voltage module, high voltage regulation
circuit, and or main power supply. This can be a bit of a tricky type of
problem to troubleshoot.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
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"Reinhard" <Ridderdq@hotmail.com> wrote in message
news:3fc65179$0$4696$1b62eedf@news.euronet.nl...
I got a ibm 6547 monitor which flickers when started up also the brightness
seems to high.
When put in a high resolution mode it stops flickering. Adjusting the screen
voltage on
the flyback has the same effect. My guess is then that there is a problem in
the HV
regulation. I checked the supply voltages to be ok. Since it is probably a
component which
has run out of its specs instead of being broken it is a bit hard for a
novice like me to
find that component.

I found the schematic (a Samsung CKB chassis) on:
http://www.promelec.ru/scheme/CKB5237.pdf

Could someone give me a few hints?



Thanks,

Reinhard



P.S. Just to check my understanding of the faqs: am I correct in stating
that this chassis
uses a separate transistor, Q503, for the high voltage creation. And the
HOT, Q406, is her
just for the deflection part?

 

[Heinz Schmitz]

On Thu, 27 Nov 2003 20:34:00 +0100, "Reinhard" <Ridderdq@hotmail.com>
wrote:

Try to get a good monitor test software from the web (like the Nokia
one). One of the tests gives a picture alternating between white
and black. If the picture widens considerably when switching from
black to white, that is a good indicator for poor High Voltage
regulation.
(Given the same deflection current, the picture is smaller if the
anode voltage is higher.)
H.