[sdiy] LCD hot rodding

Roman Sowa modular at go2.pl
Mon Apr 8 15:29:51 CEST 2024


I wouldn't want to sound rude, but if something works, even barely, like 
one row display, that's a good sign that power polarity is correct and 
reversing it then is like sticking a fork in power outlet.

Your OLED replacement was't probably fully 44780 compatible, or it was 
the other way - original one was some kind of freaky one, not compatible 
with 44780. I'd try any cheap LCD now to see what is still working.

About solid black boxes - are they in one or two lines? If there is only 
one line of black boxes, it may mean it just got power and nothing else 
plus very miss-set contrast. If you see 2 lines, it means that some 
config codes were succesfully written to the display so at least the LCD 
controller IC is working.

Test every signal of the display, at the display, during powerup: data 
bits, RS, E, to see if there is activity. One of those signals might be 
simply broken.

Roman



W dniu 2024-04-08 o 14:38, mark verbos via Synth-diy pisze:
> I have a Linn 9000 on which I’d like to replace the display. It is a 16x2 EL backlit one. I bought an OLED one and an LED lighted one from Mouser. Inspired by what Forat does, I got bigger ones. The original display uses a 14 pin, dual row connector.
> First I plugged in the OLED one it looked great, but only the top row displayed. Checking my work, I noticed that I had the power pins reversed, according to the document I was referencing. I switched them and now the display is dead. It turns out the document I was looking at for a 14 pin connector on a LCD display was wrong  and I had gotten lucky having them the right way to start. All the other wires buzzed out ok, I’m afraid to buy another display, unless someone tells me it’s possible to get it working.
> 
> Second, I plugged in the LED backlighted one today. The backlighting looks great, but I only get solid black boxes all the way across the screen.
> 
> Does anyone know about these things? What am I doing wrong here?
> 
> Mark
> 
> PS. The Linn’s power supply was already melted down when I got it. I brought that back to life. This thing has the Forat sampling mods, which is a rat’s nest. I have software 7.01 (7.09 is the latest). Emails to Forat bounced. Is he still in business?
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