Dell E193FPc Power Cycles After Several Hours

[xxsn0blindxx]

Hi,

This is my first post to the forum. I have been working with computers professionally for many years and after throwing out several bad monitors I decided to try fixing them. I have had luck with simply replacing capacitors on a few so far, but I have run into a snag with this Dell E193FPc 19" monitor. When I first tested it, it would not power on at all. After replacing all of the capacitors it powers on and works great for a few hours, but then it turns off and the power switch LED constantly flashes between green and orange like it is trying to power on. Turning the unit off with the power switch and turning it back on again will restore power, but within a few minutes the power cycling condition occurs again. If I turn it off and disconnect AC power over night I get the same behavior (works for several hours then power cycles).

I found another thread about this monitor that has pictures and maybe some other potentially useful information.
https://www.badcaps.net/forum/showthread.php?t=14834

All of the capacitors were replaced with identically rated capacitors from reputable manufacturers (rubycon, nippon, nichicon).

I have taken measurements on all of the transistors, but honestly I'm not sure how to tell if they are bad or not. Measurements were taken using the diode function on my multimeter. In case it isn't clear I took measurements from the B, C and E terminals of each transistor in every possible way, first with the positive probe on the B terminal and negative on the C terminal, then with the negative on the B terminal and positive on the C terminal and so on. If the reading was an immediate over limit it is denoted as OL, if there was an initial reading that ramped to an over limit I have noted the initial reading before over limit as some thing like .89->OL indicating a reading of .89 before going to over limit.

Any help you guys can provide would be greatly appreciated.

Position * Model * B+/C- * B-/C+ * B+/E- * B-/E+ * C+/E- * C-/E+
Q201 * 41 54 t * OL * OL * OL * OL * OL * .89->OL
Q202 * 46 5 t * OL * 1.4->OL * OL * 1.2->OL * 1.8->OL * 1.7->OL
Q205 * W04 55 * 0.906 * 1.9->OL * 0.910 * 0.882 * 0.785 * 0.781
Q206 * W04 55 * 0.897 * 1.9->OL * 0.910 * 0.878 * 0.785 * 0.781
Q207 * T06 53 * 1.8->OL * 0.864 * 0.909 * 0.877 * 1.348 * 1.9->OL
Q208 * T06 53 * 1.8->OL * 0.862 * 0.910 * 0.877 * 1.348 * 1.9->OL
Q209 * C5706 * 0.246 * 0.246 * 0.611 * 0.433 * 0.612 * 0.172
Q210 * C5706 * 0.246 * 0.246 * 0.610 * 0.431 * 0.612 * 0.169
Q211 * C5706 * 0.247 * 0.247 * 0.608 * 0.443 * 0.607 * 0.180
Q212 * C5706 * 0.247 * 0.247 * 0.610 * 0.443 * 0.609 * 0.179
Q901 * A733P * OL * 0.846 * 1.1~1.8->OL * 0.859 * 1.5~1.8->OL * OL
Q902 * C945P * 0.845 * OL * 0.860 * 1.1-~1.4->OL * OL * 1.683

[xxsn0blindxx]

Re: Dell E193FPc Power Cycles After Several Hours

Hate to be "that guy" bumping my own thread, but any guidance at all would be greatly appreciated, I'm kind of stuck at this point.

[PhoebeAnn]

Re: Dell E193FPc Power Cycles After Several Hours

All I can give is moral support I'm afraid.

I have a similar problem that started about a week ago. We leave our systems on 24/7, so the monitors go into sleep mode. One of our Dell E193FPc monitors (9 years old on Dec 6) now won't turn back on by using the power button. Wiggling the power cord at the monitor connection turned it back on for a while, so I cleaned and lubed the line cord receptacle and eventually replaced the line cord. But only physically unplugging & replugging the monitor will switch it back on, at which point it displays a screen I'd never seen before: "DELL Genesis Display Perfection", but that turns out to be normal - or at least it happens on other Dell monitors.

Assuming there's some software that gets rebooted at power-on, it looks like the monitor is failing somehow, requiring that reboot, which will restore it to life. Curiously, I don't have to wait, as I would for a heat-related failure. A quick off-on does the job, and it's good for another cycle, which can be a couple of hours or days.

I'm going to do the search-for-bad-capacitors thing and otherwise have a 10,000 foot look at it, and will report back.

[CapLeaker]

Re: Dell E193FPc Power Cycles After Several Hours

did you check the board for bad solder joints?

[PhoebeAnn]

Re: Dell E193FPc Power Cycles After Several Hours

The display was left on, as is usual, overnight last night. As I was walking to the kitchen in the dark to feed the cat, I saw the display light up momentarily, then go dark. The cycle repeats every couple of seconds. So, I think it's definitely a backlight problem, probably a power issue. Feels like the voltage rises to a point where the display lights up, but just then a component fails (e.g., a capacitor shorts) and the voltage falls again.

Finally got the thing apart, and a thorough visual inspection through a 4x loupe with a bright light, showed not very much. Solder joints are solid and shiny, capacitors all look good, no suspicious signs or smells anywhere. I don't have the facilities to do any of the troubleshooting procedures outlined in the manual, so I'm just going to replace the monitor at this point, but keep the old parts to play with when I can find the flat space and equipment to test with.

At least it started up OK when I got it all back together .

[xxsn0blindxx]

Re: Dell E193FPc Power Cycles After Several Hours

I finally got some free time to play around with this one again. Despite all of the solder joints looking fine I went ahead and re-soldered the PT201 and PT202 transformers as well as the Q209-Q212 transistors. I ran it Friday to Tuesday non-stop without shutting off so fingers crossed, I think that may have fixed it.