IIgs RGB monitor repair question.

IIgs RGB monitor repair question.

Post by Rob » Mon, 03 Jun 2002 13:21:05



Anyone know what would cause a IIgs RGB monitor to slowly increase in
brightness\contrast?  What components may be bad?
When it's first turned on the display looks normal but as it warms up the
brightness and contrast slowly increase to the point where it's too bright.
I even have the brightness and contrast dialed all the way down.

-Rob

 
 
 

IIgs RGB monitor repair question.

Post by Mark Cumming » Mon, 03 Jun 2002 20:39:07


I have two monitors doing exactly that over a 10-30 minute period. What
happens is the Screen and Focus voltage are increasing beyond their normal
value. Even adjusting the EHT transformer Screen and Focus down doesn't
solve the problem completely. You might be able to get the Screen voltage
about right to give the right brightness, but the Focus will be out of range
causing a fuzzy screen. You could try that if you take appropriate
precautions.
I believe the fault is in the EHT transformer itself, but have yet to proove
it. I have one good monitor that I hope to swap parts with to proove it, but
havn't got time at the moment. I have replaced lots of components in mine
that were a bit out or damaged, but the fault stayed the same.
I have not found a source of those EHT transformers anywhere. As far as I
can tell they are not available. I have tried Mitsubishi and Apple in
Australia without success.

Mark


Quote:> Anyone know what would cause a IIgs RGB monitor to slowly increase in
> brightness\contrast?  What components may be bad?
> When it's first turned on the display looks normal but as it warms up the
> brightness and contrast slowly increase to the point where it's too
bright.
> I even have the brightness and contrast dialed all the way down.

> -Rob


 
 
 

IIgs RGB monitor repair question.

Post by Rubywan » Thu, 06 Jun 2002 16:38:11


Rob writes ...
Quote:

> Anyone know what would cause a IIgs RGB monitor to slowly increase in
> brightness\contrast?  What components may be bad?
> When it's first turned on the display looks normal but as it warms up the
> brightness and contrast slowly increase to the point where it's too bright.
> I even have the brightness and contrast dialed all the way down.

 ....

     Have run into the same problem. As Mark indicates, you may be able to
get a good display by adjusting Focus and Intensity on the HV module ...

http://home.swbell.net/rubywand/Csa2MONITOR.html#011 .

This will usually let you move the adjustment range for your external
controls so that getting a good picture is possible.

     What seems to be a long-term fix involves replacing filter
capacitors. It is discussed by Eric Jacobs at ...

http://home.swbell.net/rubywand/Csa2MONITOR.html#034 .

     Some safety precautions are discussed at ...

http://home.swbell.net/rubywand/Csa2MONITOR.html#003
http://home.swbell.net/rubywand/Csa2MONITOR.html#004 .

Rubywand

 
 
 

IIgs RGB monitor repair question.

Post by Stephen Sha » Tue, 18 Jun 2002 04:20:03



> I have two monitors doing exactly that over a 10-30 minute period. What
> happens is the Screen and Focus voltage are increasing beyond their normal
> value. Even adjusting the EHT transformer Screen and Focus down doesn't
> solve the problem completely. You might be able to get the Screen voltage
> about right to give the right brightness, but the Focus will be out of
> range causing a fuzzy screen. You could try that if you take appropriate
> precautions.
> I believe the fault is in the EHT transformer itself, but have yet to
> proove it. I have one good monitor that I hope to swap parts with to proove
> it, but havn't got time at the moment. I have replaced lots of components
> in mine that were a bit out or damaged, but the fault stayed the same.
> I have not found a source of those EHT transformers anywhere. As far as I
> can tell they are not available. I have tried Mitsubishi and Apple in
> Australia without success.

Try HRDiemen or Konig. Google should find them. If you quote the number/s that
appear on your fbt/lopt they should be able to give you a match.

- Show quoted text -

> Mark



>> Anyone know what would cause a IIgs RGB monitor to slowly increase in
>> brightness\contrast?  What components may be bad?
>> When it's first turned on the display looks normal but as it warms up the
>> brightness and contrast slowly increase to the point where it's too
> bright.
>> I even have the brightness and contrast dialed all the way down.

>> -Rob

--
--

Remove the invalid from my e-mail address to reply to me directly.

DagWOOD - Tiger's older brother DAG

 
 
 

1. Sounds from RGB Monitor (was RE: IIGS RGB...)

Concerning the sounds from turned-on-cold monitors;

All color and many mono CRT devices have degaussing circuits in them. The sound
you hear is the coil around the body of the CRT being fired off, degaussing
the tube. All of them do it, and some make more noise than others. And yes,
they make less noise with time. There's nothing good or bad about noise or no
noise, operationally. Except if it stops working completely, in which case no
noise is a symptom. If the colors in a supposedly even-colored area changes
from spot to spot, there's a good chance the degausser is out. To see what it
would look like, hold a magnet such as a speaker near the screen. There's a
varistor which controls this in most sets, and if it gets weak, it may not
operate quickly enough for you to hear it, or even to work correctly. If it
stops working, replacing the varistor usually fixes it. It's a $1.50 part.

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