AOC 2217v goes blank after power on.

[Heliotropic]

My problem is the same as ones I've seen posted here and on the net.
When I turn on my monitor I can see my desktop display perfectly for about 3-5 seconds, but then goes blank. It is not going into "sleep" mode. I can hold down the power button to shut down the monitor. When I power it back up, I get the same result everytime...desktop display for a few seconds, then black.
I've tried the suggestions I've seen for similar problems people have posted, but I'm still having no luck.

Here's what I've done so far:
Replaced all 10 of the capacitors (c802, c803, c905, c908, c922,c915, c917, c918, c939, c940) though none of them looked bad by bulging or leaking.
Replaced diode (d906) because it had a little discoloration on the circuit board around it.
Desoldered and scraped clean the coils (L903 and L904).
Reheated quite a few other solder points on the board incase of cracked or cold solder joint.

If possible I'd like to avoid troubleshooting (and buying) every little component on this board by trial and error, so I'm hoping someone can help me narrow it down.
Here are the pictures of the circuit board and schematics.
http://i746.photobucket.com/albums/x...rcuitboard.jpg
http://i746.photobucket.com/albums/x...schematic1.jpg
http://i746.photobucket.com/albums/x...schematic2.jpg


Thanks for any help.

[PlainBill]

Re: AOC 2217v goes blank after power on.

1. Note the links in my signature on attaching pictures and do that. I dont go to other sites for pictures - I've been burned once.

2. Thanks for supplying schematics. That will earn extra help AFTER you attach the .jpgs.

3. What brand and series capacitors did you use.

4. Even though in your case it's 3-5 seconds, these symptoms are often referred to as 'two seconds to black'.

PlainBill

[Heliotropic]

Re: AOC 2217v goes blank after power on.

https://www.badcaps.net/forum/attach...1&d=1286574554
https://www.badcaps.net/forum/attach...1&d=1286574554
https://www.badcaps.net/forum/attach...1&d=1286574554

The brand of capacitors are Panisonic and all but 3 are FM series. The c905 is a TS-HB, c939 and c940 are EB series. I didn't realize they were different when I ordered them, and with my very limited knowledge of electronics, I probably wouldn't have even thought to check. Is that going to be a problem?

It probably is closer to 2 seconds before it goes blank, I didn't use a stop watch and figured the reader would get the general idea.

Thanks for the help.

[PlainBill]

Re: AOC 2217v goes blank after power on.

https://www.badcaps.net/forum/attach...1&d=1286574554
https://www.badcaps.net/forum/attach...1&d=1286574554
https://www.badcaps.net/forum/attach...1&d=1286574554

The brand of capacitors are Panisonic and all but 3 are FM series. The c905 is a TS-HB, c939 and c940 are EB series. I didn't realize they were different when I ordered them, and with my very limited knowledge of electronics, I probably wouldn't have even thought to check. Is that going to be a problem?

It probably is closer to 2 seconds before it goes blank, I didn't use a stop watch and figured the reader would get the general idea.

Thanks for the help.

Using general purpose caps in the 12V supply or the inverter WILL cause the two seconds to black problem. Unfortunately, the schematic is a little too small to identify which ones are the non-FM series. A link to the schematic would be a big help.

What is the part number of the Inverter Controller (the 16 pin IC?)

PlainBill

[Heliotropic]

Re: AOC 2217v goes blank after power on.

Using general purpose caps in the 12V supply or the inverter WILL cause the two seconds to black problem. Unfortunately, the schematic is a little too small to identify which ones are the non-FM series. A link to the schematic would be a big help.

What is the part number of the Inverter Controller (the 16 pin IC?)

PlainBill

The pictures I linked in my first post display larger than the ones shown on the second post...but you won't visit external links...so I'm a little suprised you're requesting a link now.
Regardless, the only place I was able to find schematics for this monitor was at elektrotanya.com (download link here). The site isn't in english but "Get Manual" link is. Also, the manual itself is in Japanese but the schematics are legible enough as you can see from the pictures. The .doc file schematics are much sharper and easy to read.
The part number for the IC is 715G2510-2.
Hope that helps.
Thanks again.

[PlainBill]

Re: AOC 2217v goes blank after power on.

The pictures I linked in my first post display larger than the ones shown on the second post...but you won't visit external links...so I'm a little suprised you're requesting a link now.
Regardless, the only place I was able to find schematics for this monitor was at elektrotanya.com (download link here). The site isn't in english but "Get Manual" link is. Also, the manual itself is in Japanese but the schematics are legible enough as you can see from the pictures. The .doc file schematics are much sharper and easy to read.
The part number for the IC is 715G2510-2.
Hope that helps.
Thanks again.

Read this FAQ for the reason for uploading pictures to this site, not photobucket, etc. Also, I had one case where pictures uploaded to a third party site were unreadable by a .jpg viewer. It made me wonder what had been inserted in them - and why.

EB series are not acceptable for C939, C940. They require Panasonic FM, FC, or other equivalent low ESR caps.

The part number 715G2510-2 is not a legitimate IC number. Perhaps if you read it off the IC or attached a good picture?

As far as the 'two seconds to black' issue, I'm going to recommend two tests. First, accurately measure the resistance of the secondaries of the inverter transformers. Shorted turns in a transformer will reduce the output voltage and cause this problem. The resistances should match to within 3%.

Next, try substituting a known good CCFL for each of the existing ones, 'walking it through' each of the 4 output connectors to see if one of the existing CCFLs is bad.

PlainBill

[Heliotropic]

Re: AOC 2217v goes blank after power on.

EB series are not acceptable for C939, C940. They require Panasonic FM, FC, or other equivalent low ESR caps.

The part number 715G2510-2 is not a legitimate IC number. Perhaps if you read it off the IC or attached a good picture?

As far as the 'two seconds to black' issue, I'm going to recommend two tests. First, accurately measure the resistance of the secondaries of the inverter transformers. Shorted turns in a transformer will reduce the output voltage and cause this problem. The resistances should match to within 3%.

Next, try substituting a known good CCFL for each of the existing ones, 'walking it through' each of the 4 output connectors to see if one of the existing CCFLs is bad.

PlainBill

So do I need to replace C939 and C940 EB series capacitors first, before I go any further? Or will they work long enough to find the cause of the "black" issue?
Does TL494IDR SOIC-16 sound more like the IC number you're asking for?
I'll try checking the transformers. Im assuming they cant be tested on the board and need to be pulled for testing, correct?

[smason]

Re: AOC 2217v goes blank after power on.

The pictures I linked in my first post display larger than the ones shown on the second post.

Perhaps, but they're still unreadable.
Can you not post pictures of the actual boards?

[PlainBill]

Re: AOC 2217v goes blank after power on.

So do I need to replace C939 and C940 EB series capacitors first, before I go any further? Or will they work long enough to find the cause of the "black" issue?

That is a judgment call on your part. The EB series caps should not directly affect the inverter. However, I am of the opinion that the excessive ripple on the 5V supply associated with failing caps is responsible for corruption of the EEPROM.

Does TL494IDR SOIC-16 sound more like the IC number you're asking for?

That is a legitimate number AND the part has been used in inverters. It also happens to be an IC that may make troubleshooting the inverter more difficult.

I'll try checking the transformers. Im assuming they cant be tested on the board and need to be pulled for testing, correct?

Nope - they can be tested in circuit. All you are doing is comparing the resistance of the secondaries - the windings that connect to the CCFLs.

PlainBill

[Heliotropic]

Re: AOC 2217v goes blank after power on.

Perhaps, but they're still unreadable.
Can you not post pictures of the actual boards?

Maybe these will help...

[Heliotropic]

Re: AOC 2217v goes blank after power on.

On T801 and T802 (pwr xfmrs) I'm getting 0 ohms between 1 and 4, also 0 ohms between 3 and 6.
I get 'open' between 1 and 6, 3 and 4.

Shorted?

[PlainBill]

Re: AOC 2217v goes blank after power on.

On T801 and T802 (pwr xfmrs) I'm getting 0 ohms between 1 and 4, also 0 ohms between 3 and 6.
I get 'open' between 1 and 6, 3 and 4.

Shorted?

No, that's normal. The primaries of these transformers are only a few turns of a (relatively) heavy gauge wire.

Notice I said secondaries. Pin 8 is one end, the @#$%@#%@!$ that drew up the schematic obscured the other number.

PlainBill

[Heliotropic]

Re: AOC 2217v goes blank after power on.

No, that's normal. The primaries of these transformers are only a few turns of a (relatively) heavy gauge wire.

Notice I said secondaries. Pin 8 is one end, the @#$%@#%@!$ that drew up the schematic obscured the other number.

PlainBill

My mistake, I was thinking 1-6 side were the secondaries.
I'm at about 470 ohms on pins 7 and 8.

[PlainBill]

Re: AOC 2217v goes blank after power on.

My mistake, I was thinking 1-6 side were the secondaries.
I'm at about 470 ohms on pins 7 and 8.

That does it. Note my original suggestion.

First, accurately measure the resistance of the secondaries of the inverter transformers. Shorted turns in a transformer will reduce the output voltage and cause this problem. The resistances should match to within 3%.

PlainBill

[bonney]

Re: AOC 2217v goes blank after power on.

I would say you have a weak or lazy CCFL

[Heliotropic]

Re: AOC 2217v goes blank after power on.

That does it. Note my original suggestion.

PlainBill

Is that not what i just did?

[PlainBill]

Re: AOC 2217v goes blank after power on.

Is that not what i just did?

Did you? "About 470 ohms" does not tell me that you measured both secondaries and the two readings matched to within 3%.

I emphasize several things repeatedly.

1. I don't have a crystal ball, I can't see what is happening.

2. I'm not a mind reader, I only know what you say (yes, I realize this works both ways and sometimes I'm negligent on the information I give).

3. The 'customer' often does not recognize the significance of what he sees. The worst example that comes to mind occurred about a year ago. The guy had a 'two seconds to black' problem on a Gateway monitor. All caps looked fine, according to him. After trying several things over a few days, I asked for pictures. Surprise, surprise. Most of the caps on the board had bulging tops. He 'didn't think they looked bad'.

4. I have a real life. It's not the best one possible, but I enjoy it. I have a low tolerance for anyone who does not give the information I request. Fortunately, there are others who are more tolerant.

PlainBill

[Heliotropic]

Re: AOC 2217v goes blank after power on.

Did you? "About 470 ohms" does not tell me that you measured both secondaries and the two readings matched to within 3%.
PlainBill

Yes, actually I did. Your original statement said:

First, accurately measure the resistance of the secondaries of the inverter transformers. Shorted turns in a transformer will reduce the output voltage and cause this problem. The resistances should match to within 3%.

You did not request me to report the resistance readings of each.
I guess the correct reply to the post would have been, "Yes, they match within 3%". But using my "crystal ball" I assumed you wanted a number, in which I replied:

I'm at about 470 ohms on pins 7 and 8.

I assumed that you too had a "crystal ball" and would know that both are about 470 ohms.
Now, to be more exact, T801 is 472 and T802 462.

1. I am not an electronics technician, and as I stated in my second post, my knowledge is limited. Therefore, describing exactly what and where to test would save us a lot of time. By "what and where" I mean by board location, I do not know the name of everything on a circuit board.

2. As can be assumed by point #1, I do not have the tools of an tech. I only have a simple cheap multimeter and soldering iron, so please keep in mind that my testing abilities are limited.

3. If I'm in over my head just say so and I'll move along.

4. If this forum is more for advanced people, say so and I'll move along.

5. If you do not have the tolerance to help someone that has with little to no knowlege of the subject at hand, or an understanding of the question you ask, then a help forum is not for you.

Now I understand you are trying to help, and any help is appreciated, but your condescending posts are not helpful at all.

[shovenose]

Re: AOC 2217v goes blank after power on.

Lol. Lol. Lol. Lol. Lol. Lol. Lol!!!
Ok everyone cheer up!

[k0i_]

Re: AOC 2217v goes blank after power on.

does this monitor got no english service manual to download?