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Cfag12864b-wgh-v, Doa?

ibovegar

New member
Hi all,

I'm having some problems with my CFAG12864B-WGH-V. The symptoms are;
nothing happens when I turn it ON!!! This makes me crazy assuming it's a superficial problem. I've trippelchecked my connections and can't seem to find any damage to the PCB, missing components, bad solder point etc, so i reckon the display itself is ok. The EL backlit has not been connected yet. One thing I noticed is the Vee output voltage, it measures only -0,27V (pin2, Vss as reference). Err, isn't it supposed to measure -10V??
Anybody had this problem before?

- Vegar
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CF Support

Administrator
Please advise on the connections you have made to the board, and we can proceed with helping resolve this issue.
 

CF Support

Administrator
You shouldn't have the RST line tied to your supply voltage. You should either connect it to the reset pin on your micro, or to a port on your micro, and you should clock it after power up to reset the processor.
 

ibovegar

New member
Connected RST to a port on the micro, and clocked it after power up. This did not solve my problem, and I'm pretty sure the LCD controllers were reset. A couple of times there were some vertical lines that slowly faded away. I got the software used for testing from this thread
 

ibovegar

New member
This is strange... When I turn on the display with R (read) asserted, the vertical lines appear, slowly fading away. The longer the disp have been off, the brighter the lines are when I turn it on. On the contrary the lines does not appear when write is asserted (low). The lines appear when Vo measures about 2,65V, with respect to ground (Vss). The potmeter is set around 5,5ohms, and when i adjust it CW or CCW the lines dissapear.
 

CF Tech

Administrator
It has to be something analog, or that the display got toasted.

Maye try using an external supply to manualy set Vo to -3.5 volts (Vlcd = 8.5v).

You said that Vee was not working, so maybe whatever killed that killed the controller too.
 

ibovegar

New member
Hipp hipp!
Hardwired Vo with -3,5V and turned the damn thing on, and guess what, it works. Ergo, my assumptions were correct, the negative voltage generator is busted. How this could have happened i don't know. Still, I get the vertical lines when i turn the contrast down, and I guess this is, as you say, caused by the analog part of the circuit. I've debugged the code using JTAG and got the program running, so the LCD controllers obviously works.
 

ibovegar

New member
Nice one :D

You are the definition of good customer support. Quick response time, very good technical support and obliging compensations. By the way, I love your displays, nice and shiny.

My precious....
 
Originally posted by ibovegar
The potmeter is set around 5,5ohms,
Could it be that your potentiometer is such a low value that you are completely loading down the Vee output? What is the pot value? I think a 10Kohm pot would do.
 
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