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ACER 1916B LCD Monitor won't start when cold

It seems this 19" LCD won't start up when it is cold. If you leave it for a bit then it will eventually start up. The customer reported that it had a swimming effect, but I did not see that happening. I did notice that the backlight seemed to dim and brighten on it's own once in a while.

I'm assuming that the CCFL tubes or the inverter are the cause of the dimming, but the startup problem is weird. The screen blinks the LED and you hear a high voltage like squeak and the lcd flashes bands momentarily, but no pic or menu is displayed. After it gets warmed up, it will run for days without incident.

I really hate to throw this one out without trying to solve it's problems. It's a 2005 model.

Any ideas out there?

- Tim -

Reply to
Tim
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First thing I'd check is electrolytic capacitors in the power supply and throughout the rest of the monitor. Cold faults are the classic symptom of bad capacitors, I wouldn't be surprised if you find some of them bulging or leaking onto the PCBs.

Reply to
James Sweet

Well I got the monitor opened up, and I found 5 jiffy popped electrolytics, all on the PS board, and all the same value (470uf @ 25V, made by CapXon). All the other caps look excellent. I'll replace those puppies, and let you know the outcome. I think I'll try to put in some with a bit higher voltage, if I can find some that will fit into the enclosure.

Thanks for the heads up,

- Tim -

Reply to
Tim

Same voltage should be fine, those caps likely came from the infamous electrolyte scandal of a few years back. Make sure you scrub off the goo.

Reply to
James Sweet

"James Sweet" wrote in news:UhhIj.1995$ie3.1131@trndny02:

he probably should use low ESR,105 degF switcher-grade caps,too.

--
Jim Yanik
jyanik
at
kua.net
Reply to
Jim Yanik

Won't hurt, though I think people obsess over the 105 degree (it's C, not F) thing, if anything in a monitor is approaching 100C, something is wrong.

Reply to
James Sweet

yup seen this in power supplies- motherboards. the caps that come from china i call them chinese crackers.

Reply to
ZACK

OK I replaced the bad caps. There wasn't any goo on the PCB at all. The final count was 3 x 470uf 25v and 2 100uf 10v. The ones I had were a higher voltage, but they fit ok. The monitor came right up and seems to be fully functional. I am using it as my shop monitor right now.

Thanks for your help, James.

- Tim -

Reply to
Tim

Obsess? No. Read the capacitor manufacturer's specifications: 1000 hours life at the rated temperature. If you chose a lower temperature part it will work, but have a lot shorter operating life. How many times do you want to repair something for the same problem? Would you like to recap or replace a computer motherboard every couple months, to a year? Also, as the ESR starts to rise, the electrolytics generate more internal heat. Operating temperature is a complex issue. Ambient temperature, airflow, dust buildup, component spacing all affect the capacitors. Use low temp parts if you're cheap, but use better parts if you want them to last.

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Reply to
Michael A. Terrell

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