Compaq 7750 monitor color problem

yes it can be fix. the problem inside your monitor.
lose contact or damage degaussing coil.
sometimes it's the crt lose contact.

Compaq FS 7550 has no built-in speakers. However, the FS7550 monitor comes with a pair of detachable, independently powered JBL Platinum Series speakers, which can be mounted on sides on the monitor.

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CreativeTECH

Service manual:
http://elektrotanya.com/?q=showresult&megnev=Compaq%20&megnev2=7500&kategoria=monitor&kat2=all

The VGA cable and pins are OK.
Look for bad solder joints on the circuit board mounted on the end of the picture tube socket. There should be transistors that drive each colors.

Check the pins on the cables. Single color presentation but clear picture indicates the pin for a particular color is borken on teh cable. Remember Red Green and Blue are mixed to make other colors. If you have predominantly one color then its due to cable not haveing all pins inserted properly or damaged.

if you could be in montreal your problem could be solved

Could be faulty graphics chip or faulty screen. If you can hook up external monitor and picture is fine then probably faulty screen. If external monitor shows same problem the faulty graphics chip. Take to repair shop and let them have a look.

you can change the monitor or you can repair the monitor, check the agp cable.

Check the CRT Circuit

it is possible that solder joint at the back of the tube is dry.
resolder it.
Have a try
TIA

check the pin # 1 of video input cable { broken or Bent }
if it is ok then there must be a problem with the cable or RGB Processing Circuit { Normally Dry Soldering of a faulty IC in the circuit of CRT BASE} .