34450a OLED display suddenly dimmed - Page 1
Forum section: electronics / repair

author: Aphelion
author_rank: Contributor
timestamp: December 26, 2022, 01:41:08 pm
content: Good day everyone. I have a keysight 34450a bench multimeter that suddenly the display got very dim when I turned it on. Usually I set it to the lowest possible brightness setting as it has the OLED screen. Now I can't even use the meter unless I max out the brightness on it.The multimeter is just 3 months past its warranty and has not yet been calibrated since. Re seated all of the connectors and cleaned them to no luck. I was wondering whether or not this is a display driver issue and should I try to replace the holtek ht16511 chip on it. Still trying to contact my local keysight distributor on repair options but so far is unresponsive.Can't afford to lift up the display and check the part number for it for now as I don't have a spare meter yet for work. Might break the fragile thing doing so. Attached pictures are what I was able to take a picture of the display module.Sorry in advance for any grammar mistakes, english is not my native language.... any help is greatly appreciatedEDIT: The meter is used daily, last power down it was still fine. Only after turning it on again the next day it showed the issue

author: Aphelion
author_rank: Contributor
timestamp: December 26, 2022, 01:46:42 pm
content: here are pics of the display at min and max brightness settings

author: Aphelion
author_rank: Contributor
timestamp: December 26, 2022, 01:53:42 pm
content: cont.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 26, 2022, 02:38:52 pm
content: Sadly i think you'll have to remove the board to see the display markings,the black rectangle blob on the fpc is normally an controller, or at least a driver icYou could get lucky to retreive some informations if we can find a part numberthe Holtek ht16511 datasheet is availablehttps://pdf1.alldatasheet.com/datasheet-pdf/view/103039/HOLTEK/HT16511.htmlpage 10 should give you an working example, but without part number it's only guessingyou see 5v and a 30v lines, pls check them, could be the -30v who's funky

author: Aphelion
author_rank: Contributor
timestamp: December 26, 2022, 03:48:00 pm
content: Measured between VDD and VSS, got around 3.3v which should be the supply voltage. VSS and VEE measures 0v.EDIT: I think VEE should not have voltage as it is driving an oled display, may be wrong though as I am basically a noob at this

author: coromonadalix
author_rank: Super Contributor
timestamp: December 26, 2022, 05:59:27 pm
content: follow the datasheetyou may or have ground levels in a meter, some sections are isolated for one or the other (analog and digital section) you may get falses valuesfind the display ground with the holtek chip and check is -30 volts, be careful not to slip when taking measurementsAnd no service manual is available for this model, i could be wrong (just never saw it)

author: floobydust
author_rank: Super Contributor
timestamp: December 26, 2022, 06:23:03 pm
content: I would check the OLED HV rail. Pin 29 at the far end, across tantalum C119. Fed by Q103 which seems to be a switch, power comes in at R104, from the motherboard. See if the display is getting enough voltage. Panel power range is 10-20V I would guess here it's around +15V. What size/resolution is the display?Note the front panel board has provision for a boost converter U103 etc. but 0R jumper R143 bypasses it.The display cable says SSD1322 (controller IC), Y829BR1-12.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 26, 2022, 07:45:07 pm
content: you have a yellow tantalum capacitor C105 and aluminums capacitors, they can give you some voltages, take note of them on a sheetAttached PDF file is an possible lcd layout 30 pins with the same controller, it can give you some idea

author: Aphelion
author_rank: Contributor
timestamp: December 28, 2022, 09:18:58 am
content: Okay, after using the meter again the past few days the bootup screen of the meter has burned in letters from modes I usually use on it (continuity and voltage). I have yet to check the meter again as suggested but I suspect it may be an oled burn in issue instead of the controller.Would something like this work fine as it basically uses the same controller?PHP 2,505.01 | 5.5 Inch 16PIN Green Or Yellow OLED Screen Module SSD1322 Driver 256*64 8Bit Parallel SPI 3/4-Wire Serial Interface Porthttps://a.aliexpress.com/_mtfTUYeAlso noticed that some various sizes has same pins and controllers and resolutions, so I guess a smaller screen could technically work?

author: Swainster
author_rank: Frequent Contributor
timestamp: December 28, 2022, 11:40:10 am
content: Ooh, I have 3 of these meters, all came with dead OLEDs. So yes, the OLED is almost certainly worn out. The display that you linked does indeed look like the correct display, and the price looks quite good too i.e about what I paid. Get the "no board" version.The biggest difficulty with swapping the display out is separating it from the display PCBA as it is stuck on with one big piece of double sided sticky foam tape. My preferred technique is to stick the display board onto my 3D printer hot plate at 90C to soften the glue, then run a box cutter blade between the display and the foam (not the foam and the PCB), lubricated with plenty of isopropyl alcohol. If you do it right then you can reuse the sticky foam for the new display. When refitting the new display, to align it properly, put the FPC through the slot in the PCB and lock it into the connectorbeforesticking it down.The friend/dealer/enablerwho sold me these meters has shown them working with the smaller (and much cheaper) 3.5" display which has the same FPC driver. Once behind the front panel lens it looked pretty good, though of course everything is much smaller.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 28, 2022, 04:42:20 pm
content: Quote from: Aphelion on December 28, 2022, 09:18:58 ami have sent you an pdf for a compatible model, take you time and you will find a physical compatible one, not the one from aliexpress who would need to be fittedThe WEX025664D has many equivalents with the same controller, but in theses times, prices are excessives to say the least

author: Aphelion
author_rank: Contributor
timestamp: December 28, 2022, 06:15:04 pm
content: Yep, still haven't gone around to checking everything else first before pulling the trigger. Meter is decommissioned for now as the longer I use it more the more the display dims currently...Back to the ol ut61e for now.

author: Aphelion
author_rank: Contributor
timestamp: December 28, 2022, 06:20:42 pm
content: Dang, and what I've read so far the displays were originally meant for POS systems which are always turned on for extended periods.Have you found any info on your end as to why these displays die prematurely? Went with a keysight instead of a rigol dm3058e expecting reliability but I guess even top brands have lemons🫤.

author: Swainster
author_rank: Frequent Contributor
timestamp: December 29, 2022, 02:25:27 am
content: All the units I received had displays that were already totally dead, however you could see digits etc burnt in, even from the back side of the display i.e. through the silver backing. The one I'm looking at right now was burnt in clear enough that I can see that they had obviously spent significant time measuring a value of 011.8xx - 0.11.9xx on the 100V range in remote control mode... they should probably have turned off the display if no one was looking at it directly.I suspect all my units came from the same source, maybe a production environment, though cosmetically they were pretty good - especially the first 2 - still had the sticky film on the display. The last one I got for the local equivalent of USD75 as it also has a main board problem. As I already had a spare display I figured it was worth taking a punt, even if I just keep it as spares for the other 2. Overall, I'm not impressed with the OLED durability (not just limited to this instrument, but OLEDs in general), but the readability is amazing. I personally wouldn't buy one new, but replacing the display is easy for someone with basic DIY skills so bargains can be had.Regarding monochrome OLED displays, you can see that some are specc'd in the low 1000s of hours. In my own experience of other OLED devices, I've seen significant burn in after 6 months on always on devices with minimal screen saving functionality. I haven't noticed any screen saving at all on the 34450A so being totally burnt out in a year of always on use seems plausible.

author: Aphelion
author_rank: Contributor
timestamp: January 10, 2023, 11:35:12 am
content: Keysight offered their RTK warranty, as apparently the meter was under 3 year warranty. But their processing is taking way too long and I got my replacement parts (plus I needed to ship the meter to them, which is basically costs more than the replacement that I got).Here are some pics of the display that I got. Can't get the serial number of the original screen as the foam tape was a PITA to remove.

author: Aphelion
author_rank: Contributor
timestamp: January 10, 2023, 11:36:09 am
content: Here's the replacement display, installed on the meter

author: Swainster
author_rank: Frequent Contributor
timestamp: January 10, 2023, 11:44:11 am
content: Got the yellow version - nice! Actually I think it looks better than the original green.

author: Aphelion
author_rank: Contributor
timestamp: January 10, 2023, 12:12:16 pm
content: This has helped immensely with the replacement process, thank you

author: voltsandjolts
author_rank: Unknown
timestamp: January 10, 2023, 01:11:54 pm
content: Quote from: Aphelion on January 10, 2023, 12:12:16 pmCan you confirm where you purchased the OLED display?Was it the one you linked above in reply #8 ?

author: Aphelion
author_rank: Contributor
timestamp: January 10, 2023, 01:31:39 pm
content: Quote from: voltsandjolts on January 10, 2023, 01:11:54 pmWhat I got is from an oversees seller that is shipped through lazada, but should be similar to the aliexpress one that I posted earlier. Went the lazada route as shipping only took about 4 days even though it is a little more expensive.https://s.lazada.com.ph/s.gCz1LPretty much just ensure that you get one that uses a SSD1322 driver IC and has a 256x64 resolution. As Swainster said, even the smaller and cheaper 3.12 inch ones will probably work fine as they also use the same driver IC and pinout.

author: Aphelion
author_rank: Contributor
timestamp: January 10, 2023, 02:27:56 pm
content: I found what seems to be what keysight is using for their displayshttps://m.alibaba.com/product/60690176570/PM-OLED-Rectangle-5-5inch-Green.htmlThe old OLED display has UG-5664ASGGF01 printed on its ribbon connector.

author: Aphelion
author_rank: Contributor
timestamp: January 10, 2023, 02:35:02 pm
content: Also found the datasheet of the thing, apparently it is rated for a minimum of 40k hours. Also datasheet states that it should have a specific power up/down sequence to actually preserve the thing. Don't know whether or not it is implemented though.https://datasheetspdf.com/mobile/670317/UnivisionTechnology/UG-5664ASGGF01/1

author: coromonadalix
author_rank: Super Contributor
timestamp: January 10, 2023, 05:01:38 pm
content: thats 4.5 years always on .... short life ??

author: Aphelion
author_rank: Contributor
timestamp: January 10, 2023, 06:41:41 pm
content: Quote from: coromonadalix on January 10, 2023, 05:01:38 pmHeck, I always turn off mine and set it to minimum brightness and it died early. May be a very bad batch of displays.

author: Hxhusn
author_rank: Newbie
timestamp: January 27, 2024, 02:44:47 pm
content: My friend's Keysight 34450A had the same problem last year, but he found a replacement on Ali.The display looks pretty good！URL:https://www.aliexpress.com/item/1005006494624672.html

author: voltsandjolts
author_rank: Unknown
timestamp: January 27, 2024, 04:01:33 pm
content: Alternatively, not using your store, we can get it at half the price:https://www.aliexpress.com/item/1005006150123067.html

author: floobydust
author_rank: Super Contributor
timestamp: January 27, 2024, 06:37:25 pm
content: Quote from: Hxhusn on January 27, 2024, 02:44:47 pmStore open since August 2023, 0.0% positive feedback and ripoff pricing.Please find a new way to buy your Lambo.