So i have a GLCD, that doesn't have any part number or even a manufacturer (The logo is there, but looks like somebody etched away the silkscreen that might tell the manufacturer) and i've been sitting by it trying to get it to show stuff, but no results.
So far i was able to power it up and tweak the contrast, but that's all. Whenever the sketch on the arduino starts running, the display just blanks out and shows nothing (u8glib seems to be the only library supporting this driver).
I'm also not 100% sure with the pinout, but i ended up tracing it from the driver chip:
1 - GND
2 - VCC
3 - Constrast
4 - DI
5 - R/W
6 - E
7-14 - DB0-DB7
15 - CS
16 - RESET
17 - MA
18 - goes to a collector of a random transistor
19 - NC
20 - NC
I'm also adding few pictures, that might help you to troubleshoot the display, but i have found nothing on Google.
Also those electrolytic caps in the bottom right, those are repair caps, before them there were tantalum caps that had low resistance, so i replaced them...
So i hope we're going to find an answer how to get it to show something, thank you all for your replies
Support for LC7981 has been added to U8glib long time back. I recently add access to another LC7981. Surprisingly nothing was visible. After closer investigation, i noticed, that the contrast setting is wrong in the setup code for the LC7981. Actually the contrast setting was fine for the first display, but the one i recently got required very different values.
Please have a very carefull look to your display while using u8glib. It might be working, but the contrast might be wrong. Look from all different angles and with proper light. Maybe you can see something.
Support for LC7981 has been added to U8glib long time back. I recently add access to another LC7981. Surprisingly nothing was visible. After closer investigation, i noticed, that the contrast setting is wrong in the setup code for the LC7981. Actually the contrast setting was fine for the first display, but the one i recently got required very different values.
Please have a very carefull look to your display while using u8glib. It might be working, but the contrast might be wrong. Look from all different angles and with proper light. Maybe you can see something.
Oliver
Well i don't see any settings in the sketch for contrast, but i'm using a trimmer to set the contrast anyway, so i don't think the problem is there... But thank you for the help
Actually my second display had two problems: The internally generated voltage was too less and the bias setting in the init code was not correct for the second display.
Which voltage do you have for the trimmer? It must be around -15 Volt (or even higher). How is this voltage generated?
Oliver
Edit: Without any uC attached, you should be able to turn all pixel on and off just by moving the wiper of the trimmer from one end to the other.
Actually my second display had two problems: The internally generated voltage was too less and the bias setting in the init code was not correct for the second display.
Which voltage do you have for the trimmer? It must be around -15 Volt (or even higher). How is this voltage generated?
Oliver
Edit: Without any uC attached, you should be able to turn all pixel on and off just by moving the wiper of the trimmer from one end to the other.
That's actually a good point, because i have the trimmer between GND and +5V, altough i'm able to swipe through the whole contrast settings (from not visible to really visible). I also googled a part where the replaced caps are being connected to, and the datasheet says its a voltage multiplyer, but there's no inverter, unless it's built in the columm and row drivers...
I was also hiding away, that some of the lines and columms are missing, i think it's just a problem of the zebra strip beneath the glass, but most of the lines won't dissapear nomatter how hard i push on the metal frame, so that might be rellevant to this too.
olikraus:
Well, looks like you have some contrast at least.
What is the output voltage of pin 18 with respect to GND?
Could this be the missing -15V?
Oliver
It indeed is! At the least contrast it has -10V and at the max contrast -9V, so i might be able to continue now by my own. I might drop a question if i'll need help, but surely gonna post about how it ended up!
Thank you Oliver for helping me, i really apriciate!
Alright, so it seems like the inverter chip is broken, so i just re-used my preamp power supply, that i made earlier, but wasn't powerful enough (it's a +18/-18V, so 7805 and 7915 will do the business!
