Main > Monitor/Video Forum
I think I broke my CRT :
Zebidee:
Find someone local that knows CRTs - you might get lucky and they find something simple. I've never had to set an ABL pot, or even seen one before, but I don't work on VGA monitors either (SMPS power supplies for CRTs all basically the same though). ABL is something I normally see as a flyback pin and on the schematics, with something like what lilshawn said and "leave this alone" written there, so usually I just do that. There are ways like using a variac to raise voltage slowly, and you could find a schematic or search the might Internet for further clues as to how that pot should be set. Somebody has done it before.
Good practice is to always use a Sharpie or white-out or similar to mark the original positions of pots before you move them, at least if you aren't sure what they'll do. Best would be to take an ohms measurement across the main terminals (while powered down please :D ).
Robbbert:
Most adjustable circuits are designed so that the centre position will be close to the optimal setting, so you could set the ABL pot to the middle of its range. If the circuit hasn't been damaged, it should work at that point, even if not exactly correct.
Next, if you did hit that black post, you might have fractured its soldering to the PCB. Check that it is secure and not wobbly. Lastly, it appears to be some kind of push-on connector, so give it a twist to remove any internal corrosion.
Finally you can turn it on and see if you made any difference (good or bad).
One of the unfortunate things about power supplies these days is that a tiny fault can cause a chain reaction of all kinds of expensive parts all blowing up. But I guess you'll never find out if that happened.
trick72:
Thanks guys,
One thing I found today was that if I removed a certain plug from the NECK BOARD of the tube (a cable that is going from the neck board to the main chassis board), than the board seems to work again. Power stays on fine, the LED on the chassis board even goes GREEN when it "detects" the VGA signal when I power on my PC ! So it detects that it receives a picture that is in sync (the led goes from RED to GREEN the moment my PC sends a correct VGA signal). Also the tube itself powers up, although I do not have any neck glow so I don't see any image, probably because that cable is unplugged. The screen itself stays black.
Not sure if this can be of any help, and I already placed a local advertisement for finding a local CRT technician, but I thought I would share this anyway...
I attached an image of the cable I disconnected... it's a wide cable with small wires so I don't think there is any high voltage going thru this...
Thanks.
Mike A:
Stop poking around blindly. You will wreck the monitor and make it more difficult to repair.
Zebidee:
That black wire you think you might have touched is just the ground for the screen voltage (is likely attached to the neck yes?).
Make sure the male end is soldered in properly (no cracks etc) and that you get proper connectivity to ground at both ends. It may just be that the screen voltage isn’t getting grounded properly. Maybe your touch was just hard enough to knock it loose.