Repairing CRTs? Dell P992

[Ed Oscuro]

Well, I picked up a nice cheap ($16) Dell Trinitron P992 manufactured in 2002. It works beautifully with my XRGB-2 and Surprise Attack...

...except for a nasty red-tinted screen when there's no input, and red lines stretching drunkenly (angled) across the screen - closer together at the top, and slightly shorter near the middle of the screen.

What are my options here?
Thoughts: Return and try to find another copy, try to get it repaired locally, find another monitor (this one is 15-pin only; it may be possible to do better).

Some playing around and just basic CRT knowledge makes me believe that the convergence circuit is shot. It's a shame because the thing is generally beautiful otherwise. Tapping the side of the screen produces the Trinitron Shimmer only slightly, much less than the older (larger, slightly heavier, composite-able and breaker-tripping) Compaq P110. It has a maximum resolution of 1920x1200, which would make it a great monitor for most any application.

I've got about a week to mess around before I have to return it for my tiny refund. I could ask a local repair shop if they will fix it, but I fear they will ask $200+ to get it fixed, in which case I'd be better off looking for other used monitors.

Edit: I called a local place, diagnostic alone would be $60. Whee

[cools]

Photo of the problem?

[Ed Oscuro]

Here you go (300KB+). I guess you can thank Imageshack's automatic lousy resizing for the image not being just a hair under 10MB

The reddish background was somewhat darker in person, and the white OSD message is only blown-out due to it being a highlight out of the camera sensor's dynamic range. It doesn't look quite that bad in person. The lines are just as visible as they look here though.

[cools]

The red and the lines disappear when there's input, and don't show up on a black screen?

[Ed Oscuro]

No, the red and lines don't disappear, they stay behind the image. You can see that the reddish background isn't actually flush with the edge of the screen (that's the bright red line on the left, the camera wasn't perfectly level). I was able to get Surprise Attack's output centered properly; it looked correct, except for the wavy red lines and red square. I could sort of correct for the reddish square by tweaking the red balance on the supergun or (I suppose) color temperature setting. The geometry controls on the monitor mostly did nothing, as far as I recall / could tell. That's the black screen you're (sort of) seeing. The white message is to connect input. I used the monitor's built-in degaussing function a few times btw.

[Womble]

Looks like the red gun is being overdriven when there is no input, the slanty lines are normal if the brightness per gun is way high.

[Ed Oscuro]

Looks like the red gun is being overdriven when there is no input, the slanty lines are normal if the brightness per gun is way high.

Those lines are there during normal operation too. That explanation should still hold true though. Any idea on a repair?

[brokenhalo]

the KLOV forums have a section specifically on monitor repair, and there are some fantastic guys over there that could probably help you fix it. i'd suggest posting this over there ed.

[dpful]

There's nothing wrong, if you can turn down the red gun, either from the outside or from a pot on the inside. Search for knobs, menu, whatever that will just turn down the red. All monitors make those lines in whatever color is adjusted up too high.

[Ed Oscuro]

There's nothing wrong, if you can turn down the red gun, either from the outside or from a pot on the inside. Search for knobs, menu, whatever that will just turn down the red. All monitors make those lines in whatever color is adjusted up too high.

This is not a user-serviceable monitor, it's got a case just like any other computer monitor.

HOWEVER!

Looking around by chance brought me to this page which opens up a whole new way of looking at the problem. If I can find the monitor interface cable being mentioned, I may be able to access what appear to be "digital pots" (NVRAM or something) that controls some settings inside the monitor. It'll be much cheaper than having it serviced professionally. Only problem is that it's not guaranteed to work, but it sure sounds like it will and if it doesn't I'm only out $16 + cost of the cable.

I found that page here. That and this are likely all a person needs. I just need to be careful not to kill myself.

I'll give this a try.

That's if resetting the monitor doesn't work - there may be some way of doing a reset with the OSD buttons but I'm not holding my breath.

[dpful]

wow, interesting page and cable.

That looks like a solution. If you want to dink around in the mean time (or if you can't get the program to work), inside the monitor on the chassis or neckboard, you still might be able to find pots for factory set brightness levels. They would be 3 pots marked R,G,B, level, or gain (or six pots if level and gain are both there), or all in an identical looking cluster or in a row (unless on the neckboard- then maybe on opposite sides). All other pots in there should be for sync and convergence stuff. Maybe a single pot for general brightness.

Remember that there's an overall brightness knob on the back of the flyback transformer (the black thing with the red wire leading to the suction cup on the crt). That would get rid of the lines, but not the pinkness.

[Ed Oscuro]

Actually, the flyback transformer wire is white on the P992 (and oddly enough it's also white on the monitor in my Stratovox cabinet). I looked it up on Wiki and indeed the cable leading from the flyback is usually coated with dust that seems more like grease. Before I put the case back on I might just wipe down the flyback wire (I did that a bit with the little bit I could reach inside the chassis), never realized what a good idea it was. I didn't see any pots and I'm not going looking especially for them, and even if I do I'll still try the software fix first.

[dpful]

if you get back to it, the pots are those two circles on the flyback transformer itself (in the wikipedia pic). One is brightness and one is focus.