Samsung monitor - 2232GW - power on issues (possibly not a caps fault?) - Page 1
Forum section: electronics / repair

author: SolderSucker
author_rank: Regular Contributor
timestamp: September 20, 2017, 10:11:22 am
content: I have a Samsung 2232GW monitor, it's ten years old and I love the display hence I don't want to replace it (can't really afford to either).Some months ago it started to exhibit the well known power on issues so I replaced all of the electrolytics (except for the 100uf 450v) with new, high quality, 105 degree electrolytics. Suffice to say that a number of the old caps were bulging, but not leaking.All was well for a few months but power on problems have returned, a little different this time though as now after a few hours switched off and then powered on, the overall display will be dim but is particularly dark on the left side; it will rapidly flicker then blank out completely after a few seconds. If I leave it like this for a few minutes (blank display, power still on) then power off and on again all is well. So there's a warm up required.I've taken it apart again, checked the ESR of all of the new caps (they are fine and physically they look fine too) and the old 100uf 450v electrolytic also has good ESR. Not sure if it's worth replacing that (I'd need to order one).Any thoughts please as to the cause of this latest fault? (note: this only started a few days ago).ThanksEdit: Here's a photo of the board that I found online:http://www.ccfloffer.com/bookpic/01/2232BW_Power_Board_IP-45130B.jpgModel no: IP-45130BI'm tempted just to buy a new board from China, but is it possible that the power board itself isn't at fault?

author: Armadillo
author_rank: Super Contributor
timestamp: September 20, 2017, 01:29:05 pm
content: Use a magnifying glass, check for poor/dried/cold solder joints.I suspect the old capacitors may have leaked and caused some broken traces. Just my suspect only. So you may use a multimeter on continuity mode to trace it out, including the vias for break in continuity.

author: Toasty
author_rank: Regular Contributor
timestamp: September 20, 2017, 01:30:19 pm
content: Backlights / CCFLsccflwarehouse.com is a source I use.You'll need the exact length & diameter to replace them all. Work can be tedious and frustrating. Bulbs are easily snapped/broken.You may also consider a complete LCD replacement screen assembly.T

author: SolderSucker
author_rank: Regular Contributor
timestamp: September 20, 2017, 03:58:08 pm
content: Quote from: Armadillo on September 20, 2017, 01:29:05 pmThere were definitely no leaks from the old caps, they were just bulging at the top with no leakage at all.Good point about dry joints, I'll check again.

author: SolderSucker
author_rank: Regular Contributor
timestamp: September 20, 2017, 03:59:23 pm
content: Quote from: Toasty on September 20, 2017, 01:30:19 pmInteresting, I hadn't thought of that. But why would all those on the left fail in a more obvious manner when cold?

author: gnif
author_rank: Unknown
timestamp: September 20, 2017, 04:09:36 pm
content: LCD backlight drivers are natorious for driver mosfet failures... either intermittant (as in your case) or complete. Usually the metal film capacitor next/near it dies along with it. I have repaired many LCD monitors simply by replacing the driver mosfets and caps.

author: Toasty
author_rank: Regular Contributor
timestamp: September 20, 2017, 04:15:16 pm
content: It's typically the positive end and in my experience it frequently seems to happen there. If you open it up, you'll see that end is darker in color. Just as fluorescent lamps do when they fail.You enjoyed a long life out of that monitor. Personally, I'd invest in a newer and bigger model. Just my 2¢T

author: SolderSucker
author_rank: Regular Contributor
timestamp: September 20, 2017, 04:48:51 pm
content: Quote from: gnif on September 20, 2017, 04:09:36 pmSo in this photo:http://www.ccfloffer.com/bookpic/01/2232BW_Power_Board_IP-45130B.jpgWhich parts need replacing?

author: SolderSucker
author_rank: Regular Contributor
timestamp: September 20, 2017, 04:53:26 pm
content: Quote from: Toasty on September 20, 2017, 04:15:16 pmI know, but I hate throwing things out when they can be economically repaired.

author: Toasty
author_rank: Regular Contributor
timestamp: September 20, 2017, 05:02:52 pm
content: I too am a believer in that. BUT, there comes a time to say "See ya, old friend. Glad we spent some time together."Your looking at ~$50 for parts and your time. The learning curve & the "crap, they don't bend..." scenario.T

author: gnif
author_rank: Unknown
timestamp: September 20, 2017, 05:07:41 pm
content: Quote from: SolderSucker on September 20, 2017, 04:48:51 pmCan't see them there, its a rarther small/simple one in comparison to the ones I have dealt with. They might be surface mount on the back, but I doubt it.

author: SolderSucker
author_rank: Regular Contributor
timestamp: September 20, 2017, 05:10:35 pm
content: Quote from: gnif on September 20, 2017, 05:07:41 pmThere is another PCB in the monitor with surface mounted electrolytics and other components, I guess the Mosfet and is on that?Edit: in fact, the other board inside the monitor is of course the main driver board, here's one:http://www.ccfloffer.com/bookpic/01/Driver_Board_BN41-00890A.jpgWhich part on that could be causing backlighting issues?

author: gnif
author_rank: Unknown
timestamp: September 20, 2017, 05:24:59 pm
content: Quote from: SolderSucker on September 20, 2017, 05:10:35 pmPlease show a photo of the back of the power board.

author: SolderSucker
author_rank: Regular Contributor
timestamp: September 20, 2017, 05:28:22 pm
content: Quote from: gnif on September 20, 2017, 05:24:59 pmDo you mean my own power board or any one of that model number? If you're wondering if there are any components on the back then, as I recall, there aren't.

author: gnif
author_rank: Unknown
timestamp: September 20, 2017, 07:52:02 pm
content: Quote from: SolderSucker on September 20, 2017, 05:28:22 pmYou are not going to get much help if you do not provide the basic information needed to be assisted. The power supply board, the back of which will contain surface mount parts, for example a quick google shows this:https://picclick.com/Power-Board-IP-45130B-BN44-00127U-For-SAMSUNG-2232BW-Brand-260933249365.htmlThe thrid picture clearly shows some surface mount components on the back of the unit. Please post a complete picture of the back of the PCB.

author: SolderSucker
author_rank: Regular Contributor
timestamp: September 20, 2017, 08:33:05 pm
content: I'm afraid that I don't have the means to take a digital photograph as my digital camera is faulty (something else that needs repairing or replacing when I can afford it).However, how about the photo of the rear of the PCB in this auction, does that help:http://www.ebay.com/itm/New-Power-Board-IP-45130B-BN44-00127U-For-SAMSUNG-2232BW-A011-/231410588330Zooming in on it doesn't reveal the chip markings but maybe it's good enough?

author: gnif
author_rank: Unknown
timestamp: September 20, 2017, 08:50:38 pm
content: Yes, that helps somewhat. See attached, those two chips are the driving mosfets that drive the backlighting transformers, one or both may be falting as they get warm, it is the most common cause of backlight failure in monitors like this.

author: SolderSucker
author_rank: Regular Contributor
timestamp: September 20, 2017, 09:02:33 pm
content: Thanks very much. You mention about one or both mosfets failing when they get warm but it's when the monitor is cold that the problem occurs. Presumably they could still be at fault of course.Edit: I've just found the service manual for the 2232BW (mine is the GW but they share the same boards), it can be downloaded here:https://www.electronica-pt.com/esquema/monitores/samsung-esquemas-monitor/samsung-2032bw-2232bw-lcd-monitor-26187/

author: SolderSucker
author_rank: Regular Contributor
timestamp: September 21, 2017, 11:20:45 am
content: @gnif - I've had the back off the monitor again and checked what is engraved on those two chips, which is as follows:SIM830977330(both are the same)Where would you recommend that I buy replacement chips please, and are there any more modern equivalents which I could perhaps more easily source? I'm in the UK so a UK supplier is preferred but I have a feeling I'm going to have to get some from China.Thanks

author: Rasz
author_rank: Super Contributor
timestamp: September 21, 2017, 02:25:03 pm
content: STM8309$2 for 2-5 with free shipping on ebaybut it does sound like dying ccfls, on the other hand $2 is a good price for a long shot

author: SolderSucker
author_rank: Regular Contributor
timestamp: September 21, 2017, 02:31:39 pm
content: Thanks, I'll take a look.

author: Armadillo
author_rank: Super Contributor
timestamp: September 21, 2017, 02:40:48 pm
content: It doesn't seems like the protection circuits came into play here and on all 2 CCFL at the same time?ehm..... Agree with the long shot but should continue to look further.Edit: That mosfets can be checked with multimeter.

author: Rasz
author_rank: Super Contributor
timestamp: September 21, 2017, 02:46:49 pm
content: can you reliably check rdson in milliohm range of a mosfet with a multimeter? it doesnt sound like those transistors are dead, but they might be dying/cooked.

author: Armadillo
author_rank: Super Contributor
timestamp: September 21, 2017, 02:56:49 pm
content: Quote from: Rasz on September 21, 2017, 02:46:49 pmMaybe lost a few watts, gets a bit warmer......Sure don't fits OP description of problem when cold.But never mind ..... try the long shot.... plug and play always the easiest and fastest.