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Old Aug 13th, 2010, 09:47 AM   #31
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Hmmm,

great thread indeed. Just took my screen apart, today. It just went black, no led, nothing. Power brick and cable are fine of course, I have made sure.

Most likely the pcb board. Has anyone found a replacement? I am not able to locate the damaged component I am afraid, don't have so much knowledge...

Unless A1082's fix works for all of us!

Would appreciate any input here.

Thanks!
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Old Aug 17th, 2010, 05:00 PM   #32
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Can I Borrow a PS for a 20" LCD Cinema Display?

Actually, can a friend of mine in Toronto borrow a power supply to see if his display works? He found it abandoned in a dumpster and doesn't want to pay $120 plus for a new PS unless the unit works. It's the Apple Cinema Display A1081 and uses the A1096 661-3760 Power Adapter for Apple 20" Cinema Display DVI (65W). Local authorized dealers had none in stock and were unhelpful except to say, "Either buy a new PS from us which we will have to order, or throw the thing out because it probably doesn't work anyway."

He has transportation so can bring the display to you to plug in to your PS.

If anybody in the GTA is willing and able, PM me and I'll send you some contact info.
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Old Sep 18th, 2010, 05:54 AM   #33
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Hello I'm also trying to fix an A1082. The 3.3V regulator was gone, but with that replaced, it's still not working. It seems the (LM)2672 nearby is outputting 0V on all pins except the 24.5 V on Vin. Does anybody know what voltage that is supposed to be outputting? It seems to head through the choke and out to the inverter. Maybe 12V?
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Old Sep 18th, 2010, 06:10 AM   #34
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Measured 950 and 564 ohms on the resistors and plugging in reverse through the datasheet value examples gives me 3.301V. Another 3.3V source? Hmm...
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Old Oct 7th, 2010, 09:30 PM   #35
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Thumbs up Yet another A1082 display fixed by replacing LM1117 with LM1086 !

Quote:
Originally Posted by A1082 View Post
I successfuly fixed my ACD what was dark and made 1short/1long/1short blinks.

I'll make pictures and post them here, but in short:
- replaced failed "1117-3.3SJ" LDO regulator [5V to 3.3V] located in a middle of main PCB.
This time I used slightly modified LM1086 what should handle max 1500 mA instead of 800 mA by original.
THANK YOU, A1082!!! Another satisfied "customer" for whom your fix worked like a charm.

Also, many thanks to Freakin for the really detailed and accurate disassembly instructions (see message #11 in this thread). I probably would have broken something if not for his help.

I too have a 23" Apple Cinema Display A1082 which one day went black and made the LED power indicator blink in the pattern short-long-short. The Apple tech note on this exact symptom, which is at:

Apple LCD displays: Power light flashes

says: "Make sure you are using the correct power adapter with the display."

Now, since I never had any other power adapter, I knew that I had to have the correct one (A1097 90W). I therefore figured that the power adapter is probably defective. I bought a new one from Apple support (of course, the 3-year AppleCare had expired about two months prior) and eagerly plugged it in - only to get the same symptoms (black screen, short-long-short blink on the LED).

Then I found this message thread.

Since I am reasonably handy with a soldering iron, I thought I would give it a try. The idea of A1082 to substitute a higher-amperage equivalent (LM1086) for the original part (LM1117) sounded like a good one - if these things are burning out for many of us, a heftier part might be more reliable. As was noted previously, the case size is a bit of a problem - the LM1086 comes in several case variations but they are all larger than the original, and the spot where it is soldered on the board is very cramped.

Rather than try to file down the case (and risk going too deep and hitting the important bits), I soldered extension wires to the LM1086 and "mounted" it off the upper edge of the circuit board using electrical tape. I used the TO-220 case variant, which is a LOT larger than the original.

It sure ain't pretty but it works perfectly. See attached photo. Actually, it's downright ugly. The replacement part is wrapped in several layers of electrical tape to prevent shorting to the surroundings. There is a black cloth tape with foil inside that shields the upper part of the board wiring - I peeled it back as shown in the photo and then pressed it down again to hold the new part in place.

By the way, if anyone else wants to try this - there are various electronic parts suppliers where you can get these things. I used Newark Electronics (which is actually located in Chicago) - they have it for $2.50 in single quantities.
NATIONAL SEMICONDUCTOR|LM1086IT-3.3/NOPB|IC, LDO VOLT REG, 3.3V, 1.5A, | Newark.com

I also attached a picture of the lower right corner of the opened-up case, showing the two mini connectors and the sliding latch that Freakin refers to in his instructions. I thought it might help folks to visualize this before opening it up.

Also attached is the first page of a product data sheet for the LM1086 - you can get the whole thing at:
LM1086 - 1.5A Low Dropout Positive Regulators

Thanks again for a great resource. I only wish I had found this site earlier in my quest - I would have saved the $$ of buying a new power adapter that I don't need.
Attached Images
File Type: jpg Patched_A1082.jpg (891.9 KB, 410 views)
File Type: jpg A1082_lower_right_corner.jpg (473.8 KB, 193 views)
File Type: jpg LM1086.jpg (121.9 KB, 227 views)
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Old Dec 21st, 2010, 11:43 AM   #36
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Another satisfield customer!

My 20" aluminum ACD finally started shutting off after 30 minutes of use. The 1117-3.3SJ regulator had turned brown and the leads looked awful. It was not the inverter board. It looked in good shape.

I did manage to damage the one of the retaining clips getting the panel out. The clips on the 20" pull OUTWARD to disengage, not upwards. It should not really be a problem since the panel is screwed together on the sides. I will have to dremel out the clip slide so the panel will close.

Thanks again.
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Old Jan 7th, 2011, 08:12 PM   #37
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Hi guys !
First of all thank you (especially A1082) for the precious tips.
I managed to fix the logic board of one of my Apple Cinema Displays but unfortunately it looks like the LCD panel is completely gone.

I swapped the logic board, the inverter and also the cable between this and a working Cinema Display and I found out that there is something wrong with the LCD panel, and I don't think there is an easy way to fix it... am I wrong ?

Do you guys know where I can find a working (even used) LCD panel for my 23* Cinema Display at a good price ?

Kind regards,
Neeno
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Old Jan 8th, 2011, 06:09 PM   #38
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Hi Guys! Thank you for your great info on this forum! I appreciate these people who share info they found on their own because of the lack of knowledge of "Geniuses" and engineering stuff that trying to do their job quicker/easier by using cheaper components in highly cost equipment or so... And then we have an issues that they don't even want to deal with.

Anyway. I have my ACD 23" just recently died on me by everybody known power issue. But in my case there is no flashing LED or any kind of signs of life and anything prompting about what is it. I red lots of forums did the paper trick, power supply switch to 150w (brand new) and nothing did work for me. I was going to try to A1082 way but realized I have a bit different mainboard "Q4849B" instead of "*****C" and nothing is fried on it (at least looks like it, i looked with LED flash light). When I power it on nothing happenes.
So here is what I have noticed with both power adapters. To pin point the faulty part of display and at least what board is faulty and why it happens. I disconnected all cables from the main board that all the power goes to. Then connected the wall outlet power cable to power adapter and display power connector to power adapter too and measured if there is any power going to mobo by checking voltage in three prong cable that has three thick wires (red ("+"), thin grey ("ground") and black ("negative")). And "YES", I got 24.6V from 150W and 25.5V from my 90W. So, wires and power adapters were OK. Then disconnected display power cable from brick and connected the three prong cable back in to its socket. Next I connected display cable to brick and the 150W brick made three beeps inside of it and turned itself off from delivering power to mobo at all. 0.0V outgoing power. Same happened to 90W brick, but no noise or beeps have been noticed.
So, it seems to me there might be some kind of shortage on mainboard that leading to overload powerbrick and it turns itself off. But I don't see any kind of damage that been caused by shorted component on mobo. And that's why I can not check if there is any power on LM1117 since it happens with in a second or two.

Let me know if anyone have any suggestions on? I'm out of ideas and ready to sell it for parts, but don't want to give up yet!
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Old Jan 10th, 2011, 01:11 AM   #39
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2nd try

The monitor does now work but will shut off randomly or blink.

I've run with extensions off and It only makes it shut off sooner. Whatever the issue is, it has something to do with the ATMega microcontroller on the main board. Something is causing it to shut down.

My last test is to run the monitor on a PC and see if it is getting a shutdown command from the graphics card.

If you guys have any suggestions, please let me know.
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Old Feb 26th, 2011, 04:48 PM   #40
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There was a guy with 6 inverters and 2 main boards on ebay, but it looks like he sold all the main boards!

Looks like I'm going to be forced to try that resistor replacement unless you guys know where I can get a mainboard for less than $100.. I had found it for $50 but stupidly let it slip, thinking maybe it was just the $20 inverter and I should try that first. Dumb idea...
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