OLED character displays - dead in storage? or something else? - Page 1
Forum section: electronics / projects

author: TheMG
author_rank: Frequent Contributor
timestamp: June 06, 2020, 08:06:25 pm
content: Well, I installed a Winstar WP1602B, 2x16 character OLED display in a project I'm building. Got around to wiring it to the microcontroller (Arduino Mega 2560) and writing a simple bit of code to test that everything is working. Well, no luck, display remains dark.Thinking maybe these don't properly support 4-bit mode as with HD44780 based character LCD displays, I added the extra 4 wires for 8-bit mode. Still no luck. And yes, I did make sure to supply 5V to the brightness adjustment pin, which should set it to maximum brightness.What has me really scratching my head, is that I've used these exact OLED displays before, though not with Arduino, but with a 68HC11 development board, where I had absolutely no problem using them, just the same as any other HD44780 based LCD module. So, I dusted off the dev board from where it had been sitting for the last 10 years, plopped in the OLED module, loaded up a program that I know I have used before, with these exact modules, and..... NOTHING! Tried another identical OLED module I have on hand... also nothing.Am I going crazy here? I don't remember ever having any problems with these in the past, they always worked just the same as any standard character LCD module. Is it possible these things went bad just sitting there in storage for a little over 10 years (from the last time it was used, manufacturing date is actually 2007).

author: TheMG
author_rank: Frequent Contributor
timestamp: June 06, 2020, 08:32:23 pm
content: I had another idea - used oscilloscope to see if there was any sign of life at the pads that are driving the OLED panel itself. As a control, I first measure with the display powered but not initialized - I can see each row connection momentarily go low in turn, as would be expected (it's a passive matrix arrangement). No activity at all on any of the column connections.Then I loaded up the program, which displays rapidly changing text on the display, and probed the column connections again. The good news is, I see changing waveforms on nearly all of the column pins, at about 6Vpp, indicating that the module has been properly initialized and is actually trying to display something. If I connect a standard LED from one of the columns to one of the rows, it lights up.The bad news: this means the OLED panel itself is essentially dead. I already checked the zebra strips and they are conducting just fine with virtually no pressure (multimeter leds on either side of the strip) and pressing down hard on top of the panel does nothing.Do OLED displays like this have a limited shelf life? Why would it completely stop working like this, just sitting in storage, in an anti-static bag?

author: jc101
author_rank: Frequent Contributor
timestamp: June 06, 2020, 09:22:28 pm
content: I use Winstar 16x2 OLEDs and had to write a custom setup for them to work properly. I also had an issue with a flicker on write, Winstar had me adjust the timing of the the signalling to resolve that compared to the datasheet. None of the Winstar displays I've use have a pin for adjusting the brightness of the OLED.None of the OLED I had were WP1602B, they all started WEH00. What is the full part number?Does the part label on the PCB match what you think it is, were you sent the wrong part?I buy batches of OLEDs and may not install them for months, the items they are in have been in use for years - never had one come back with a failed display yet.

author: amyk
author_rank: Super Contributor
timestamp: June 06, 2020, 10:04:43 pm
content: OLEDs are moisture-sensitive. If the seal was not perfect from the factory they would've worked initially, but degraded over time. Since it's already dead you could take it apart and try applying increasing voltage (current-limited) directly between the column and row lines to see if you get any light output.

author: TheMG
author_rank: Frequent Contributor
timestamp: June 07, 2020, 01:13:14 am
content: QuoteThat's what I thought at first, which is why I dusted off the old 68HC11 development board and an old program, because I had previously (10 years ago) used the very same OLED display with that setup quite successfully.QuoteWP1602B-Y-JCS (label)P1602B is silk-screened on the PCBQuoteDid that with one of them. Absolutely zip, no light, not even the slightest bit of current flow. Not even 1uA in either direction, at any voltage. It's like it's gone totally open.I did pick them up off some random eBay seller some 12 years ago. I suppose it is possible they were either counterfeit or factory rejects from the start.

author: Buriedcode
author_rank: Super Contributor
timestamp: June 07, 2020, 02:05:39 am
content: A quick google of the part number shows it is a PLED displays. These have limited lifetimes in storage or usage of about 5 years. I have two PLED displays (one 24x2 and one 128x64) that were made back in 2007, but died around 2011 in storage (16-24C 50%). OLED's seem to have better storage life, but it is still limited to several years.A telltale sign is a somewhat milky appearance to the pixels. A true PLED display should appear completely back, maybe slightly purple but you shouldn't be able to see the pixels.

author: amyk
author_rank: Super Contributor
timestamp: June 07, 2020, 04:28:41 am
content: According tohttps://forums.adafruit.com/viewtopic.php?f=19&t=71249Quoteandhttps://www.oled-info.com/pledQuote5 years may seem like a long time for disposable consumer stuff, but there's a reason they have not displaced LCDs and VFDs in industrial applications...

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: June 07, 2020, 11:16:41 am
content: These displays (2 line dot matrix) were notorious for moisture ingress and eventual death - in storage or not. There was a period (about 10 years ago) when they were pulled from sale almost universally. I had about 100 displays put aside for a project and they have all died - all of them.Leo

author: TheMG
author_rank: Frequent Contributor
timestamp: June 07, 2020, 03:50:05 pm
content: QuoteAppears to be two pieces of glass but "sealed" with some sort of adhesive. I assume this is where the moisture ingress occurred?Here I've peeled off the polarizer and the black backing:Quote from: Leo Bodnar on June 07, 2020, 11:16:41 amWow, that's pretty bad!While the OLED display would have been kind of a neat look for this project, I guess I'm going to fall back to the good old reliable black-on-green transflective LCD character modules I've used in many previous projects.Kind of annoying that I spent hours checking and double-checking my wiring and programming thinking I was doing something wrong, only to eventually find out the damned things died on the shelf!

author: Buriedcode
author_rank: Super Contributor
timestamp: June 07, 2020, 06:21:03 pm
content: Quote from: TheMG on June 07, 2020, 03:50:05 pmIt is indeed a pity as the character OLED displays I've used looked awesome, very crisp. Whilst they aren't the same, the "best" LCD's have to offer are the vertically aligned character displays. These have better viewing angle and a much better contrast. Not the same contrast ratio as OLEDs, but far better than STN, FSTN or FFSTN (called DFSTN) plus they're fairly cheap. ($4?). Character displays don't have as big of a market, especially as pretty good graphic TFT displays are so cheap, but then you have the hassle of driving them.A random video I found comparing them:

author: TheMG
author_rank: Frequent Contributor
timestamp: June 07, 2020, 08:44:52 pm
content: Quote from: Buriedcode on June 07, 2020, 06:21:03 pmYeah, and programming isn't exactly my strong point. Only displaying alphanumeric data anyways.

author: amyk
author_rank: Super Contributor
timestamp: June 07, 2020, 10:47:44 pm
content: From that image it looks like they just sealed it with some adhesive, which would probably be somewhat permeable to moisture over time.Even the big companies have problems with them; remember these DMMs with quickly dying OLEDs?https://www.eevblog.com/forum/testgear/agilent-u1253b-display-becoming-unreadable/Personally, I avoid OLEDs completely; they just aren't stable enough.