EDU08 - no data on display


I got edu08 from another person and it seems that there is a same issue as in other threads. Back-lite is turning on in a few seconds after power connected but nothing is on LCD. When i am turning it off - i see a horizontal line sometime for a few seconds. Here is my voltage (board is powered from 4AAA batteries, ~5v):

connector top row:

3.3 0 3.3 3.3 3.3 0 3.3 0 0.5
0 3.3 3.3 3.3 3.3 3.3 0 3.3 0

Test point: 1.63v

A: 4.45
B: 3.98
C: 3.49
D: 1.073
E: 0.6
F: 2.28
G: 2.25V
H: 1.6V
I: 2.85V
J: 3.7V
K: 1.6V
L: 3.3V
M: 4.45V

One of the problem that i dont know if it was ever working. I also see that in 5m its switching off, what makes me thinking that pic controller is working and problem is somewhere in LCD circuit. I also tried to resolder connector and LCD pins, no luck so far. No shorts was found. Any help is appreciated.

Normally the backlight should turn on immediately.
Seems to be similar problem as in this case.

Thank you for reply! I checked and found no shorts or disconnects. I think that LCD Controller is dead, as voltage multiplier is not working. From schematic i think it is ST7565P based device, in parallel mode. I want to try to get one from ebay to make this device running. Could you please confirm that?

P.S. Its probably funny but i found it near trashcan for electronic waste. I think somebedody tried to assemple it but given up. So nice opportunity to try to make it online again and play with my kids.

About backlight - i found that it is corresponding logical 1 on PIC (18 pin). When i am turning on Power i see 3.3 within 1-2s from start. I tried with and w/o LCD board connected

I think the LCD controller initialization fails and this is the cause to the delay.
Indeed, maybe defective.
I think the LCD controller is ST7565R.

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I was not able to find ST7565R with 30pins (we have here 28pin version only), so ordered one with PCB where all capacitors are already soldered. Will wait few weeks until and come and let you know if it works :slight_smile: Thank you again for reply and your help, hope to have some fun with this toy.

I wish you success with the repair project :slightly_smiling_face:

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