Need help DCLCD 19" LCD Monitor - I already replaced caps

[PlainBill]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I had Sceptre X9G Komodo IV same problem, when monitor had power the powerlight blinking about 5min & monitor turn on ok long the had 110 VAC hook up the monitor, if I'm disconnect power had go same steps above again
I open can't find any caps bad but replace all but still same problem (maybe some transitor bad?)
any one know how to fix this problem?
Thanks

What caps (brand and series) did you use as replacements? Also, there are one or two small (less than 100uF) caps near the main transformer. Did you replace them?

PlainBill

[hoadle]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I check the inverter/power board find out had cold solder at quickconnect to VGA card, resolder is working final
Thanks

[wenter]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

So,guys do you think I need to replace the diod with lower readings?

[alexanna]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Well I had no intention of killing this thread but it looks like I did a very good job.
It sounds like you may unfamiliar with some of your volt ohm meter readings, And I was just trying to suggest maybe you confused milivolts with volts and ohms with k ohms or m ohms.
You said that you were seeing 5v on one pin of the logic board so to me it sounded like that dual diode was working.
I was really hoping someone would answer if there is a good way to test these.
I guess one good thing is the diode is probably not very costly, And sometimes you may have to install a known part to rule it out.
There was a question about the ohm reading you get when you connect the leads of the volt ohm meter together.
Try another set of leads see if you get closer to 0ohms.
.I really wish I could help more but I am trying to learn also.
Al.

[retiredcaps]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

There was a question about the ohm reading you get when you connect the leads of the volt ohm meter together.
Try another set of leads see if you get closer to 0ohms.

post #46 and #58 have not been yet answered by wenter. Hard to help when wenter won't or can't provide the information.

[EGuevarae]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

So,guys do you think I need to replace the diod with lower readings?

Gwt an accurate reading from the multimeter first.

[alexanna]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I think I may need one of those beers.
Al.

[EGuevarae]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I think I may need one of those beers.
Al.

Here you go :

[SMITHWHO]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Cant not remove back of monitor after removing all screws and base

all:

I have two dclcd 19" lcd monitors and one of them died a few months back. I was going to throw it out, but i decided to try to fix it. I did some research online and found that the capacitors are typically the problem, so that is why i am here.

The first thing i did was switch out the entire inverter board for the one in my monitor which already works. Once the working inverter board was put in, the broken monitor worked again - i therefore know the problem is on this board somewhere!.

The board is loaded with elite caps which i guess can go bad.

I ordered 5 caps from digikey (all exact voltage, uf specs as the ones i replaced) in hope that it would be on of the 5 larger caps. I swapped them in with no luck. I then got determined and swapped the other caps between my working and broken board. The board which was originally working still works, and the broken one is still broken.



i swapped all of the caps with the red x's on it.

What else should i do? I'm out of time today, but maybe you guys can give me some guidance

i have more pictures if they are needed

thanks,
martini

[SMITHWHO]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Can not remove plactic cover removed all screws and base should lift off but does not need help
sincerly j.r. Smith

[retiredcaps]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Can not remove plactic cover removed all screws and base should lift off but does not need help
sincerly j.r. Smith

Pry it apart. See

https://www.badcaps.net/forum/showpo...84&postcount=2

[number22]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I had problem with my similar DCLCD 19" monitor, anyway, I scavenged 2 capacitors (TEC, 16V, 1000uF) from a bad power supplies, test them out, and the monitor is work like new, the color is vivid.

Symptoms:Monitor began color shifting a while back(a year ago), greenish mostly, I didn't bother fix it, until it die out on me yesterday, open her up, find bad brand capacitors all in, didn't bother replacing all of them, just these 2 popped(CapXon, 16V 1000uF). anyway, I have been using it for like about 4 years. now it is like new, just want to share my experience, hoping it will help other. Great site though.

[EGuevarae]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

... didn't bother replacing all of them, just these 2 popped(CapXon, 16V 1000uF). .....

I hope you don't bother reopening the unit soon either.There's a good reason for changing ALL the caps except the bigger one, and with the correct caps ...

[DJM_PHX]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Ok, I have the same issue. Turns on for a second, then goes out. I put a DMM on several points on the board. But what seemed strange was the right side terminals of the circled piece (AC connection to the left) kept flashing my Fluke from 4.xxV - 5.xxV, then to OL and back. On the DMM on the left I was getting -80 Volts. Is the where the AC is suppose to be converted to DCV? If so, this could be the failed part. What type of part is it? #4G P721F 4GR

[retiredcaps]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Ok, I have the same issue. Turns on for a second, then goes out.

If you hookup a computer displaying your favorite wallpaper, do you still see it by shining a flashlight onto the screen? Also, does the power LED stay green/blue?

I put a DMM on several points on the board.

Depending on how you answer the above question, we can suggest test points on the board. The item you have circled looks like the opto isolator.

[DJM_PHX]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

If you hookup a computer displaying your favorite wallpaper, do you still see it by shining a flashlight onto the screen? Also, does the power LED stay green/blue?

I used an LED flashlight and see nothing. Tried this before.

The LED was a solid blue before then would start blinking, now it does not come on at all.

Also, why do I see a -80V on the top of the large cap and a -84V and a -85V on the leads? All voltage measurements are pulsing just as I see it from the opto isolator.

Depending on how you answer the above question, we can suggest test points on the board. The item you have circled looks like the opto isolator.

thanks

[retiredcaps]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

The LED was a solid blue before then would start blinking, now it does not come on at all.

Also, why do I see a -80V on the top of the large cap and a -84V and a -85V on the leads? All voltage measurements are pulsing just as I see it from the opto isolator.

1) If the power LED does not come on at all, measure the all the pins on the connector (just right of the optoisolator). Use a ground screw for the black probe. The red probe goes to each pin. Put your multimeter on 20V DC. List, measure, and record each pin. You are looking for DC voltage. At minimum, you should see 5V DC on one of the pins.

2) You are using the incorrect GND if you are getting negative voltages. To test the large cap, put your multimeter on 200V DC (if manual). Put your black probe on the negative leg and red probe on the positive leg. If you have 120V main voltage, the big cap should read 120 x 1.414 or roughly 160V to 165V DC. It should be a stable voltage. CAREFUL, this is high voltage.

3) The pulsing voltage is a clue. The small cap lying on its side just right of the big cap could be bad without bloating. That cap is critical to the SMPS startup process. So if you do not see any secondary voltages from #1, this small cap could be the culprit.

4) Can we clear and focused picture of YOUR board? Reusing other people's pictures (especially without telling us) doesn't help us diagnose YOUR problem. Your board could have unique characteristics not shown in someone else's photo. It is not uncommon for manufacturers to make changes on their boards. Also try to get the resolution as close to 2000x2000 as possible.

[EGuevarae]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

3) The pulsing voltage is a clue. The small cap lying on its side just right of the big cap could be bad without bloating. That cap is critical to the SMPS startup process. So if you do not see any secondary voltages from #1, this small cap could be the culprit.

I agree.That little guy has given me some trouble in the past.And is ofter overlooked.

[DJM_PHX]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

1) If the power LED does not come on at all, measure the all the pins on the connector (just right of the optoisolator). Use a ground screw for the black probe. The red probe goes to each pin. Put your multimeter on 20V DC. List, measure, and record each pin. You are looking for DC voltage. At minimum, you should see 5V DC on one of the pins.

1) Blk 0-0.03V
2) Brn 0V
3) Red 0V
4) Org 0V
5) Yel 0-0.04V
6) Red 0-0.04V
7) Blk 0-0.04V
8) Yel 0V
9) Gry 3.5V
10) Wht ~0.002V
11) Blk 0V
12) Brn 0V
13) MT
14) Red 0-0.04V
15) Org 0-0.04V

2) You are using the incorrect GND if you are getting negative voltages. To test the large cap, put your multimeter on 200V DC (if manual). Put your black probe on the negative leg and red probe on the positive leg. If you have 120V main voltage, the big cap should read 120 x 1.414 or roughly 160V to 165V DC. It should be a stable voltage. CAREFUL, this is high voltage.

The large cap measured 172V-174V. Varying like the other voltages above.

3) The pulsing voltage is a clue. The small cap lying on its side just right of the big cap could be bad without bloating. That cap is critical to the SMPS startup process. So if you do not see any secondary voltages from #1, this small cap could be the culprit.

Is the secondary voltages you are talking about the 2V variation?

4) Can we clear and focused picture of YOUR board? Reusing other people's pictures (especially without telling us) doesn't help us diagnose YOUR problem. Your board could have unique characteristics not shown in someone else's photo. It is not uncommon for manufacturers to make changes on their boards. Also try to get the resolution as close to 2000x2000 as possible.

I will have to try to borrow a dept camera to do this. I will try for today.
I have gone over the other pic and it is like mine, but I will follow up with the pic.
Number off of the board: LM004 Rev J 12/01/2003

[DJM_PHX]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

This is the best I can do today. The better dept camera is not available. I think just about everybody is out for Xmas.