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Old 09-02-2011, 11:50 PM   #1
Sanction
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Default Help with Acer P235H

Symptoms: Monitor powers on, displays desktop from ~5 seconds to ~5 minutes, then goes black. Cycling power button restores image for variable amount of time.
Image visible with heavy light.

Troubleshooting done so far: Fuse is good. No obviously burned or broken components. The board shows signs of overheating around 3 transformers.

Repair done so far: I replaced all of the large caps on the board with new ones.

I know nothing about diagnostics, but I can solder/de-solder and I can follow instructions.

I thought to replace the inverter transformers but when I tried searching for them, I only came up with a couple pages that confused me more than anything.

So if someone can help me identify the problem or at least find a suitable replacement for the 2 inverter transformers that would be great.
Attached Images
File Type: jpg CRW_8376.jpg (282.9 KB, 20 views)
File Type: jpg CRW_8371-2.jpg (208.7 KB, 33 views)
File Type: jpg CRW_8374-2.jpg (261.7 KB, 21 views)

Last edited by Sanction; 09-02-2011 at 11:52 PM.. Reason: Additional information
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Old 09-03-2011, 01:26 AM   #2
Rtech
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Default Re: Help with Acer P235H

Measure the resistance of the secondaries on the 2 Inverter transformers,if they are within 3% of each other, then the Backlights/backlight wiring may be the problem.
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Old 09-03-2011, 06:35 AM   #3
Sanction
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Default Re: Help with Acer P235H

which ones are the secondaries? each transformer has 2 connectors on one side and 6 on the other.
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Old 09-03-2011, 07:02 AM   #4
PlainBill
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Default Re: Help with Acer P235H

Quote:
Originally Posted by Sanction View Post
which ones are the secondaries? each transformer has 2 connectors on one side and 6 on the other.
The two pins are the secondary.

As a secondary note, unless there is a specific detail you are trying to show, one good picture covering the entire board gives us much more information than a number of close-ups.

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Old 09-03-2011, 06:42 PM   #5
Sanction
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Default Re: Help with Acer P235H

451 ohms on first 453 ohms on second.

The two closeup shots were to show the part number and number of connections on the transformers. I thought that might help someone crossref them with something else.
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Old 09-03-2011, 06:54 PM   #6
Sanction
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Default Re: Help with Acer P235H

Daylight pics of board:
Attached Images
File Type: jpg Front.jpg (872.2 KB, 37 views)
File Type: jpg Back.jpg (962.0 KB, 19 views)
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Old 09-03-2011, 09:57 PM   #7
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Default Re: Help with Acer P235H

Quote:
Originally Posted by Sanction View Post
Daylight pics of board:
Really clear, thanks.

The resistance readings indicate the transformers are probably good, and the caps have been replaced.

Do you have access to another monitor, or some CCFLs. At this point the best way to troubleshoot would be to substitute known good CCFLs. You don't have to pull them out of the panel, simply arrange the two panels close enough that you can hook the CCFLs in the 'test' monitor to the inverter in your monitor.

The other choice is to disassemble the LCD panel in your monitor and check the CCFLs and wiring for problems.

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Old 09-03-2011, 10:08 PM   #8
Sanction
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Default Re: Help with Acer P235H

Thanks for the help Bill.. I do have a couple other monitors so I'll give that a shot.
I think before I tear another one open I'll finish disassembly of this one down to the ccfl wiring.

Will update in a day or two lol
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Old 09-03-2011, 11:17 PM   #9
jsog
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Default Re: Help with Acer P235H

There are six small electrolytics that can cause this kind of problem. Replace them before taking apart the panel.
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