Agilent U1253A - dim display lighting - Page 1
Forum section: electronics / testgear

author: toli
author_rank: Frequent Contributor
timestamp: October 23, 2014, 06:58:40 am
content: Hi all,After a while of using my other DMM's only, I've turned on the U1253A for a quick measurement today, and guess what... the OLED display seems to be problematic. In the past I've used the low brightness setting and the display was just fine, now its barely visible at this setting. Medium is now at best what low used to be, and there's hardly any difference between the medium and high settings.I've tried replacing the battery (or actually running it off the lab PS, and it stays the same). It is usable as is when I place it on the medium setting, but its just no as good when the bench light is on and I'm trying to read the display.The device isn't under warranty, I've purchased it in the Grainger deal >3 years ago, and as Keysight have told me by phone today, its still registered under their name with a purchase date of somewhere in 2009 (which makes no difference since the warranty is limited to 3 years). I'm still waiting on a reply from Keysight about replacement cost (they say they don't repair such small instrument, and instead offer a replacement).In the meantime I was hoping to get some ideas from you guys:1 - Anyone ran across this problem and knows how to fix it?2 - If not, is there anything that's an immediate suspect in this case?If replacement cost is too high (and I suspect it will be), I wouldn't mind giving it a try.

author: retiredcaps
author_rank: Super Contributor
timestamp: October 23, 2014, 07:08:20 am
content: Quote from: toli on October 23, 2014, 06:58:40 amSearch button is your friend ...https://www.eevblog.com/forum/testgear/replacing-oled-screen-on-an-agilent-u1253a-multimeter/

author: toli
author_rank: Frequent Contributor
timestamp: October 23, 2014, 07:39:58 am
content: Thank you for that. I've looked up on Google and didn't run across this discussion.I was actually surprised by that, I though those issues are a thing of the past with the silicon they use for OLED display nowadays. I can understand it happening on older technology where the device characteristics would shift with the continuous current through it, but I didn't realize it will happen on this display. Especially given the fact it was only lightly used and was always kept at the low setting for the display.So reading that thread, and the one linked within it, I see there's basically nothing to do except for throwing it out or hoping Agilent will be willing to offer a replacement with an LCD screen for a reasonable price?

author: nanofrog
author_rank: Super Contributor
timestamp: October 23, 2014, 03:22:34 pm
content: Quote from: toli on October 23, 2014, 07:39:58 amLooks that way.Hopefully they'll make you a good offer on a U1252B (FWIW, I've had mine for ~5 years IIRC with no issues; even the original NiMH battery still holds a charge).Never did find out what happened with the meter in the linked thread.

author: toli
author_rank: Frequent Contributor
timestamp: October 23, 2014, 03:32:27 pm
content: I've had a phone call with them today. They said they can replace the screen with an LCD screen. When I've asked how can they do this if the displays are so different I didn't really get a reply. I might try giving them another call next week and ask again before I take a drive to drop it over at their lab. Or I can just let them have it and see what they come up with as a fix.This DMM really makes me wonder who's the idiot who put an OLED display that last <4 years on a device with the Agilent brand that should normally last decades. I'm still in doubt that the LCD screen will work as a direct replacement, they are completely different after all. This whole DMM/repair deal so far makes me feel really bad about the Agilent brand which I've always held in high regard. I doubt I'll be getting another Agilent DMM anytime soon, I'd rather go for another Fluke like the 189 I've added to the tool box some time ago.

author: nanofrog
author_rank: Super Contributor
timestamp: October 23, 2014, 03:46:06 pm
content: Quote from: toli on October 23, 2014, 03:32:27 pmI'd definitely take them up on it.BTW, what is this going to run you, if you don't mind me asking (assuming it's not free due to out of warranty)?Regarding the drop-in nature of the replacement, I've always suspected this is the case (i.e. simplifies manufacturing the different models). IIRC, it's just data over the pins, and the specific driver circuits are part of the screen assembly/PCB itself. Making it a plug-n-play manufacturing method of sorts by stacking together the right combination of boards & display.

author: toli
author_rank: Frequent Contributor
timestamp: October 23, 2014, 03:52:29 pm
content: 1. I don't know if its PnP since the display board seems to hold the level shifter, DCDC converter, and the display itself. In the case of a dot-matrix vs the very limited LCD, and the fact the entire menu system is different between models, I find it difficult to see how a direct replacement will work. Anyway, they say they are going to do it, I'll let them have it and see if they can indeed do it.2. Regarding pricing, I still didn't get an organized quote and I'll only get it once they review it in person, but the guy I talked to over the phone told me it'll go for 70$ (before tax I assume).

author: nanofrog
author_rank: Super Contributor
timestamp: October 23, 2014, 04:09:26 pm
content: Quote from: toli on October 23, 2014, 03:52:29 pmWill be nice to get it working at that price (certainly easier to swallow than a new meter).I hope it works, as I'd really like to know if a swap will work (never had access to an OLED model for comparative purposes). Would be really useful to U1253x version owners if it does.Perhaps disassemble and take some detailed pics of your boards before sending it off? Might help determine what they actually do, should it come back working.Also, I'd be willing to do the same with mine if it helps (you've piqued my curiosity over this again).

author: toli
author_rank: Frequent Contributor
timestamp: October 23, 2014, 04:11:41 pm
content: I've had a look over the display board today (took pictures too so I can post if you'd like), but I didn't really take pictures of the other board. I would certainly be interested in seeing pictures of the 1252, interesting to see if the display board even has the same header as the one I have (I assume it will though).

author: nanofrog
author_rank: Super Contributor
timestamp: October 23, 2014, 04:35:44 pm
content: Quote from: toli on October 23, 2014, 04:11:41 pmPlease post them. And if possible, the other board as well.I'll tear mine down, and get pics up as well as soon as I can (will need to charge the camera battery).

author: wraper
author_rank: Unknown
timestamp: October 23, 2014, 04:48:38 pm
content: Quote from: toli on October 23, 2014, 06:58:40 amIt sound like it was OK all the time and just became dim instantly. Is it so or it became dim over time?

author: toli
author_rank: Frequent Contributor
timestamp: October 23, 2014, 05:15:49 pm
content: wraper, I didn't notice it until today so I can't really say. But again, I was barely using it over the last months so it is possible that it was somewhat gradual and I didn't notice.BTW, now I notice that some parts on the display are brighter than others, specifically the secondary readout and the dBm/50R logo, these are both barely used in my use case, so looks like it is a matter of dying OLED.nanofrog, I've uploaded the pics as a .rar file to my dropbox account. Its public so you can download it directly here:https://dl.dropboxusercontent.com/u/37472979/U1253A_teardown.rarThe quality isn't that great (blame LG for the Nexus 5 camera), but I think it'll do for the purpose of spotting differences.

author: wraper
author_rank: Unknown
timestamp: October 23, 2014, 09:59:12 pm
content: It is definitely worth to check that DC/DC converter on the display pcb. As it seems just a MC33063, it is easy to calculate what output voltage should be there according to the feedback resistors values.

author: toli
author_rank: Frequent Contributor
timestamp: October 24, 2014, 05:40:51 am
content: Given the fact some parts of the display (the least used parts) are still brighter, I doubt the DCDC is to blame here.It is still usable, the medium/high setting (which are about the same now) are bright enough to use, but I don't want to wait for it to die completely, I'd rather replace it for an LCD now than later.

author: toli
author_rank: Frequent Contributor
timestamp: November 09, 2014, 09:17:41 am
content: so I have a few updates, I'd like to share.I delivered the meter to Keysight lab a week and a half ago. At the time of the delivery they seemed in doubt an LCD replacement is feaseble, which was my guess. Skeeping over another call I've had with them during the week (where they've mentioned a replacemenet will cost more than buying a new unit), they gave me a call Thursday (1 week after getting the unit) and told me its fixed. I've asked what the fix was, and they said the screen was replaced for a new one - but politely suggested that if it happens again I should just buy a new meterAs a token of good service they did this free of charge. I guess even though I still think its an idiot move to sell a meter with a stop watch of 3-4 years on the display, they did fix it and did it free of charge despite the fact its out of warranty. So that quite nice of them.I've picked it up today, and the screen does seem to be back to its former glory with a much brighter display even at the low setting.I didn't have a chance to look inside and see if there's a different panel/board revision (but I doubt it will be), but if its of any interest I comment about it later once I'm back home.

author: nanofrog
author_rank: Super Contributor
timestamp: November 09, 2014, 03:48:02 pm
content: So they replaced it with another OLED then, rather than convert it to LCD.Sorry about not getting the pics done yet.Do you still want me to post them?

author: toli
author_rank: Frequent Contributor
timestamp: November 09, 2014, 03:49:27 pm
content: A. Yes, they've installed another OLED screen. The LCD isn't a possible replacement as it seems.B. I'm sure it can be helpful if you post these pictures. I wouldn't mind taking a look, and I guess I'm not the only one.

author: nanofrog
author_rank: Super Contributor
timestamp: November 09, 2014, 03:59:23 pm
content: Quote from: toli on November 09, 2014, 03:49:27 pmI still wonder if it's a technical issue or a cost issue (i.e. would have to replace the secondary board <display driver board?> as well as the screen, so they opted for a screen replacement instead).Quote from: toli on November 09, 2014, 03:49:27 pmNot a problem, and I'm still really curious as to whether or not it's actually possible to convert one.I should have them up shortly (need to clear a hole on the bench, and check if the camera battery is charged). Also, it might be easier for future readers if you post your pcb photos on the site directly.

author: nanofrog
author_rank: Super Contributor
timestamp: November 10, 2014, 08:46:00 am
content: Here are the pics.

author: nanofrog
author_rank: Super Contributor
timestamp: November 10, 2014, 08:47:51 am
content: More pics.

author: toli
author_rank: Frequent Contributor
timestamp: November 10, 2014, 08:51:21 am
content: At first glance seems like there are indeed differences there.I'm wondering if a full-dot-matrix LCD replacement can be found instead of the OLED using the same controller. This will allow using a longer lasting LCD, and probably prolong battery life at the same time. I'll try and have a look, but I would sure be happy to get help in this regard.

author: nanofrog
author_rank: Super Contributor
timestamp: November 10, 2014, 08:56:29 am
content: Absolutely some differences, namely the OLED version has an additional display board.And it does appear they can be converted from a hardware POV. Unfortunately, it seems Keysight won't sell anyone the board OLED owners need to use the LCD display they will sell, so that puts a serious damper on things.But others may be able to get theirs converted once Keysight runs out of OLED displays, assuming they get the right customer service personnel.