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
Member
Last Activity: 01-17-2011, 02:59 PM
Joined: 12-17-2010
Location: Phoenix, AZ
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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!Leave a comment:
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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)?Leave a comment:
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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...Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
Ok then, at least one of these is bad on my board. I am going to replace both....Leave a comment:
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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....Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
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....Leave a comment:
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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.Last edited by DJM_PHX; 01-07-2011, 05:39 PM.Leave a comment:
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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....Last edited by DJM_PHX; 01-07-2011, 03:32 PM.Leave a comment:
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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.Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
Not only is the LED flashing, the screen is flashing white as well right in time with the clicking.Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
Reinstalled the board. Question, how hot should the heat sink get on the filter part of the board? It smells like plastic is burning and to hot to touch. The caps are very hot as well.
I now have a blinking LED.Last edited by DJM_PHX; 01-07-2011, 11:05 AM.Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
I'm sure that there are other devices interacting with this measurement. Across R106 I get the same measurement.Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
The resistor is ~4ohm and the cap next to it is ~1.87uf in circuit. The diodes right there are good as well....Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
Yes. When I first started looking at it I had a picture for a second or two and a power LED, but now there is nothing but the clidking.
Yes, I have always reconnected all of the wires and screwed the PCB back into the frame.
I am off work today but will double check them tomorrow.
I have already removed the large cap and I am aquiring a replacement....Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
If it would make you feel better I can start another one. I have gone through and reflowed all of the suggested points and then some. If you have some valid input, please add it....Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
That's OL with black lead on GND. 0.448 reversed.Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
When I measure between pins 5(Gnd) and 7(Vcc), I see an decreasing meg Ohm resistance. I assume the little cap is charging back thru the ground side of the cap.
Using the diode selection, OL between 5 and 7.Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
Nope, not it!Leave a comment:
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Re: Need help DCLCD 19" LCD Monitor - I already replaced caps
On D103 I get 0.058 in both directions. In the above pic, D103 is just above and to a little right of the control chip (orange and black). D101 a 0.462 and OL, D012 returns a 0.441 and OL.Leave a comment:
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