Need to repair many IBM G74 Monitor, Model #6547-0AN

I am part of an I.T. shop for a company that has many many many of thes
IBM G74 monitors. They are gradually starting to all have problems

1. Very dark - Brightness/Contrast controls are not effective an
are maxed out
2. Display wider than screen - Width adjustment has very littl
effect

We have so many, but I'd like to figure out what to look for and how t
repair them. I'm really starting to feel stupid and wasteful when w
are told to just "junk 'em" and get another. They're fantasti
monitors. I am sure the company (or at least the organization that
support) would be somewhat impressed if I could repair them with littl
trouble and expense.

The other rather embarrassing fact is that I have a EE degree! It wa
almost all book-smarts if you know what I mean and was not reall
electronics, per se. I have not been in the electronics nor th
engineering world since 1991! I have a FLUKE DMM (at home...don't hav
the model # with me) and I have soldering tools. I actually have acces
to an entire workforce of component people (our value add shop), but I'
like to eventually do this myself.

Can anybody help me here?


Thanks,
John

PS, I'm in the DFW area (Dallas/Fort Worth, Texas

 

Some monitors have an extra adjustment on the circuit board.

Indicates 'blooming' of the images. See

http://repairfaq.ece.drexel.edu/REPAIR/F_tvfaq5.html

http://repairfaq.ece.drexel.edu/REPAIR/F_tvfaq7.html

That'll cut you no slack in any repair shop.

 

See this thread
http://sci.tech-archive.net/Archive/sci.electronics.repair/2004-09/1693.html

Apparently there is a 3.3uF NP cap which goes high ESR and causes
width to "max out". Don't know about the brightness problem.

 

For the brightness problem, look at the heater in the neck of the tube, is
it glowing normally? If not then you might have a bad capacitor in the power
supply. If the heater is ok and HV is present, chances are the tube is shot.

For the width issue look for a bad capacitor somewhere around the horizontal
section.

Oh and do NOT under any circumstances try to adjust out either of the faults
unless you want to make the monitor not worth repairing.

 

According to the Google Groups archives, the width problem is due to a
3.3uF non polarized 65V capacitor.

http://groups-beta.google.com/group/sci.electronics.repair/msg/3c5efd6875333540?dmode=source


- Franc Zabkar

 

Do they have Samsung blue-label CRT's? If so, that's the problem.

Tom