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Capacitor identification / repair of Gateway LCD monitor

deat66

Jan 20, 2011
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Good Afternoon,

As I endeavor in this new world I find it most difficult to track down what a part is. Working on an LCD monitor. Found some caps that look rough and a diode tested bad. found the diode HER108 and large of the two caps Y1E 222M - the smaller cap looks just like the aforementioned one but it has 10k 6kUL as its only markings. I have found that is is a 1000 pf but I cannot find a suitable match....if I use the same additional info as the 222 (50v etc)

and then to try to find suitable matches at supply sites...... arg!

Some one tell me it gets easier....
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Do you have a photo?

Did the diode measure "bad" in circuit, or out of circuit?
 

deat66

Jan 20, 2011
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Tested in circuit, no power applied - open in both directions - for some reason it didn't it me that it may need to be out of circuit like resistors. I was using a dmm on continuity.

Also, tested 3 others in the same circuit are and all checked ok with the same type of test
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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OK, no problems. Open both ways indicates a fault with a normal diode that is pretty hard to mimic by other components in the circuit. :) (and this appears to be a normal diode).

When you say the capacitors "look rough", what do you mean?
 

deat66

Jan 20, 2011
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"Looked rough" was looking at the underside of the pcb at the solder through holes and several of them at the caps were....looked sort of like corrosion or a "track" between the legs, they are disc type caps. I didn't think to get pics, if the snow relents and I make it back to work tomorrow I'll post a couple.

Also, I used my dmm and on the side of the board that goes from the power board to the video board is a connector marked with GRD, 12v, 5v, etc and there is very little (.5v-1.8v) present...more power readings will follow with pics.
 

deat66

Jan 20, 2011
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Pics

Didn't get to do much more testing but have some pics of the caps, pcb front & back and the power out pins.....I found the diode (not shown HER 108) and the larger cap 222M. The smaller one I am still having trouble with finding a match. I think it is a .01uf but beyond that I am lost.....any specific troubleshooting tips would be appreciated as well.

TIA

David
 

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Resqueline

Jul 31, 2009
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Those cap's are 2200pf 6kV and 10pF 6kV respectively. They'd most likely be burnt (in that ccfl backlight circuit) if they were bad. What were the initial symptoms?
Try replacing the two small electrolytics in the corner around the the 8-pin IC. It also seems to me one of the big secondary cap's is bulging slightly. Any sounds?
The pic's are not good enough to see any tracking, but I don't think this is your problem.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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25,510
Is that an ACER monitor?

The power supply looks remarkably familiar to me.

If it is, I'd replace all the electrolytic capacitors in that group near the heatsink. Get some Low ESR capacitors to replace them.

From mmory you will find 2 x 470uF 25V and 2 x 1000uF 16V and a smaller (470uF 16V -- less certain about that one)

Looking at it again, it's a bit different. And I would suspect at least 2 of them as showing visible signs of death.

I strongly second Resqueline's request for symptoms.
 

deat66

Jan 20, 2011
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Evening again,

I didn't see signs of death from the electrolytic caps, although admittedly I am very new to this. They weren't bulged at the top nor did they seem to be leaking anything.

Symptoms: came in after an auto win update (including a restart) and nothing - Power light (in button) would come on but nada - replace monitor and all is well.

These are Gateway monitors and we have had 3 do the same thing within 2 weeks, all are about the same age....3 years-ish.

TIA

David
 

deat66

Jan 20, 2011
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These pics show the solder points from the caps I removed, looks like they are corroded??

The other shows where the bad diode was removed from "A" and something I don't know what is "B" , lastly a close up of the E-caps in the corner.

Hope this will help

Deat
 

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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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The front left capacitor seems to have a slightly convex top. That is a bad sign. Thet should be perfectly flat.

Having said that, it is quite possible that the only failure is the inverter.

The way to check that is to shine a torch or other good light source onto the monitor and look very carefully for an image.

Odd turn-on, turn-off behaviour is often power supply related, but it sounds like that's not the case here.
 

Resqueline

Jul 31, 2009
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1st pic is just the dried remains of solder flux that was not completely washed off during manufacture. You can clean it off with isopropyl (rubbing) alcohol if you like.

B is a ferrite bead if I'm not much mistaken. The component labels gives a clue to what it is.

There seems to be just one small cap' by the 8-pin IC btw..
 

deat66

Jan 20, 2011
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New Info - replaced the diode and now the unit comes on, displays the proper image for approximately 2 seconds then the display goes out but the power button blue "on" light is still on....

This should have been in the repair thread - my apologies and I appreciate the help!
 

Resqueline

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If one of the four fluorescent tubes are bad it'll shut off all four just like that to protect the drivers & transformers from overcurrent/-voltage. Thread hereby moved, no worries.
 

deat66

Jan 20, 2011
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dark image

OK......<sigh>.... got the diode changed as I said it comes on, then goes right back off...rechecked my fluorescent plugs and I mis-plugged one...(half in=half out). Now it comes on and appears to go back off BUT if I look closely, the image is still there now......can someone kick me down a path.....(for the 2 seconds it is normal the brightness looks good)

Much Thanks,

David
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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The problem is with the backlight.

It is either a problem with the inverter, or with one (or more) of the tubes.

I'm not sure what happens if you run it with a tube disconnected. You could try disconnecting one tube at a time and seeing if the problem is related to a particular tube.
 
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