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

[Don P]

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

Sorry about that.... here are 2 pictures. One of the signal board, the other is the bottom of the power supply board. I don't know why it won't let me load the third one, I'll post the top of the power supply in the next post...

[PlainBill]

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

I looked through all the threads to try & find my problem, but no luck. So, here goes... My DCLCD 19" "died" a couple of days ago. I noticed that after coming back to it after a while, it would not "wake up". I tried pressing the power button, but that didn't work. What did work (a few times) was to unplug it and then plug it back in. Eventually, the entire screen would be white. That's all I get on it now. The other observation was that as I was plugging it back in, the front panel power led would be momentarily purple before going to red, at which point I had the white screen, and again, the power switch is ineffective.

Thank You in advance for reading this and any comments concerning my display!

(Sigh). Open up the monitor, take pictures of the power supply (top and bottom) and the signal card. Attach them to your next post using 'Manage Attachments' - below the text entry area.

PlainBill

[Don P]

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

I looked through all the threads to try & find my problem, but no luck. So, here goes... My DCLCD 19" "died" a couple of days ago. I noticed that after coming back to it after a while, it would not "wake up". I tried pressing the power button, but that didn't work. What did work (a few times) was to unplug it and then plug it back in. Eventually, the entire screen would be white. That's all I get on it now. The other observation was that as I was plugging it back in, the front panel power led would be momentarily purple before going to red, at which point I had the white screen, and again, the power switch is ineffective.

Thank You in advance for reading this and any comments concerning my display!

[Dr Laser]

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

I would like to say thanks to this forum to give me an idea why my dclcd was blinking. I replaced the main (big) cap and also other one which was inflated. Now monitor works fine.

[DJM_PHX]

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

I removed the yellow unit and still have everything connected to ground. I think I will just take all of the caps off and the schottky diodes and sink off and measure them all.

[DJM_PHX]

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

I have removed the diode at ZD102 and I am measuring ~0 ohms across all of the devices connected to the yellow unit including the schottky diodes and the 5 caps in the filter part. Everything seems to be connected to ground!

[DJM_PHX]

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

Ok, I have replaced the bad schottky diode (10A-100V) and the burned ZD102 on the bottom of the board.

What is the yellow unit? (see attached pic)

Does any one know if ZD102 is in fact a Zener diode?
Do we know its specs (I used a 15V 500mA)?

[Th3_uN1Qu3]

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

As it is it isn't too accurate, but it'll be enough to make a good/bad type of test.

[SMITHWHO]

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

http://www.ludens.cl/Electron/esr/esr.html
try this web sight for build your own cap testor
sincerly j.r. smith

[alexanna]

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

On the bottom of the board, is ZD102 a 15V Zener diode?
see post #153

I do not know if this will help you but, The markings that I can see are a big yellow band on one end and what looks to be black or green band in the centre. My eyes are way past the 40 year old mark!
Zd102, ZD104 and ZD105 all appear to be the same color to my eyes.
Al.

[DJM_PHX]

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

I have a P/S-Inverter board # LM004 Rev 3.
If That will help you with any part identification, I will do my best to help you
Al.

On the bottom of the board, is ZD102 a 15V Zener diode?
see post #153

[DJM_PHX]

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

The 2 that I have pictured are both Schotty Barrier Diodes.
The one on the left. # FCH10U10
The one on the right # FCQ10U06
Al.

Ok then, at least one of these is bad on my board. I am going to replace both.

[alexanna]

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

Can you confirm that the units on the filter heat sink should both be schottky diodes? Like the ones on page 3 #49.

The 2 that I have pictured are both Schotty Barrier Diodes.
The one on the left. # FCH10U10
The one on the right # FCQ10U06
Al.

[DJM_PHX]

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

I have a P/S-Inverter board # LM004 Rev 3.
If That will help you with any part identification, I will do my best to help you
Al.

Can you confirm that the units on the filter heat sink should both be schottky diodes? Like the ones on page 3 #49.

[DJM_PHX]

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

That may be the problem.

BUT it is a 2SC433 transistor

Hope this helps

-Ben

Thanks Ben, but wenter's and my board is the same and the pic in #49 page 3 shows two schottky diodes. According to the spec sheet I should have 250pf for the juction capacitance. The MOSPEC has ~238pf for each direction respecitively, but the other only has ~8pf. I believe this is the bed unit. I just need to hunt them down now and get them ordered.

[ben7]

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

I pulled the filter sink and the schottky diodes. the first is a schottky MOSPEC SRF10100C which checks ok. The second I can not identify. It is a: 1 OH60C C433. If it is a schottky diode also, I believe it is bad. This is the unit that smells hot and seemed to heat up hot first on the sink.

That may be the problem.

BUT it is a 2SC433 transistor

Hope this helps

-Ben

[alexanna]

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

In #49, wenter has a pic of his schottky diodes. His and mine are the same board and monitor so I would expect the diodes should be the same. He has a SRF1060C on the right where my unknown is and according to the data sheet, both of these schottky diodes should be the same. Mine are not. My Fluke shows a flashing OL (1-, 2+) and a leakage in reverse. The other has Mohms and a large Kohm respectively.

I have a P/S-Inverter board # LM004 Rev 3.
If That will help you with any part identification, I will do my best to help you
Al.

[DJM_PHX]

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

In #49, wenter has a pic of his schottky diodes. His and mine are the same board and monitor so I would expect the diodes should be the same. He has a SRF1060C on the right where my unknown is and according to the data sheet, both of these schottky diodes should be the same. Mine are not. My Fluke shows a flashing OL (1-, 2+) and a leakage in reverse. The other has Mohms and a large Kohm respectively.

[DJM_PHX]

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

This is getting to be a nightmare!!!!
ZD102 diode is now burned out.

My bad. I jumped a solder connection.

[DJM_PHX]

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

I pulled the filter sink and the schottky diodes. the first is a schottky MOSPEC SRF10100C which checks ok. The second I can not identify. It is a: 1 OH60C C433. If it is a schottky diode also, I believe it is bad. This is the unit that smells hot and seemed to heat up hot first on the sink.