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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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21" Monitor problem: Poor brightness. Dell D1626HT/ Sony GDM-500 chassis
Lionel:
You cannot "fix" or "tweak" a weak CRT. In it's previous life, it was probably left on 24/7 ..... this is most likely why you were able to pick it up for "cheap" at a market. A CRT rejuvenator like a B&K or Sencor MIGHT be able to eek some more life and brightness out of it. Best Regards, Daniel Sofie Electronics Supply & Repair ------------------------------------ snipped: "Lionel" wrote in message I just picked up one of these beautiful 21" monitors cheap at a market. Except for this brightness problem, it works perfectly. I'm driving it Turning up all the on-screen bias & gain controls to the maximum values produces a usable, but still darkish image. I was assuming that as the monitor is about 4 years old, it'd probably just need a cleanup, & for me to tweak up the EHT, but having obtained a schematic, I now know that there are *no* internal adjustments at all! I Any tips or ideas? |
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21" Monitor problem: Poor brightness. Dell D1626HT/ Sony GDM-500 chassis
I have seen CRT's go weak where there was a lot of brightness loss,
and yet the pictures were still sharp. I think it is how the tube deteriates that indicates how it will look. Most of the time, they do go soft, but not always. Jerry Greenberg -- Lionel wrote in message ... On Thu, 7 Aug 2003 07:17:14 -0700, in , "Sofie" said: Lionel: You cannot "fix" or "tweak" a weak CRT. In it's previous life, it was probably left on 24/7 ..... this is most likely why you were able to pick it up for "cheap" at a market. A CRT rejuvenator like a B&K or Sencor MIGHT be able to eek some more life and brightness out of it. Any time I've looked at monitors with worn out CRTs, they've usually had weak contrast, & a general 'murky' look. This one has a razor sharp, very clean image, apart from the lack in brightness. (It was running when I bought it, & I wouldn't have bothered if it'd had a bad looking image.) It's worth mentioning that this beast has a digital diags port that's accessible via a hatch on the rear cover, & that the service guide says you're supposed to use some sort of proprietory device to do the initial convergence (etc) setup on it. My guess is that you need it to access all the adjustments that are normally done with trimmers, etc. |
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21" Monitor problem: Poor brightness. Dell D1626HT/ Sony GDM-500 chassis
Lionel wrote:
I just picked up one of these beautiful 21" monitors cheap at a market. Except for this brightness problem, it works perfectly. I'm driving it with a Matrox 450 Dual Head card at 1600x1200 x 32 bits at 75Hz. It calibrates correctly with a Spyder, except for the maximum brightness only being about half of what the calibraation software thinks it should be (some 93 candles per square metre vs the ~50 candles on this monitor). Turning up all the on-screen bias & gain controls to the maximum values produces a usable, but still darkish image. I was assuming that as the monitor is about 4 years old, it'd probably just need a cleanup, & for me to tweak up the EHT, but having obtained a schematic, I now know that there are *no* internal adjustments at all! I cleaned all the dirt off the HT & EHT components & resoldered a heap of joints that looked kind of 'dry' but it made no visible difference. Any tips or ideas? -- W . | ,. w , "Some people are alive only because \|/ \|/ it is illegal to kill them." Perna condita delenda est ---^----^--------------------------------------------------------------- It's a long shot, but I've seen a couple of sonys with a bad cap in the CRT heater supply. Make sure you have 6.3 v on the heater. If the CRT is weak, you might be able to try boosting it a little by using the old few turns of wire around the flyback core trick. I've never tried to do this with a monitor though, so I'm not sure if it would work. Most monitors get the heater supply from the power supply instead of the flyback. I don't see why it wouldn't work. If there are any resistors in series with the heater supply, you could try bypassing them with wire before doing anything else. I've seen quite a few of these with dim CRTs that still look reasonably sharp. It's a shame that most companies don't use the power saving features! -- Andy Cuffe |
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