Reprogram EEPROM LG monitor

[physicsguy]

I have an LG 31MU97-B monitor that has gone dead for the second time. The mainboard was replaced at the beginning of 2018 which, of course, solved the problem, but I don't really want to go on buying mainboards for it every 2 to 3 years.

The problem is most probably an EEPROM, an MX25L8006EM2I-12G.

I took the monitor to the company that replaced the mainboard before, and they said they hadn't a SOC8 adaptor for their universal programmer – acquisition, labour, and it might not being the problem would make repair an uneconomic proposition.

Reading into it, I found I could buy a CH341A USB programmer quite cheaply. However, further reading disclosed that although the programmer could power the chip at 3.3V, it sends programming signals at 5V. Furthermore, no CH341A lists an MX25L8006EM2I-12G as a chip it is suitable for. There is a hack of rewiring the CH341A to use the 3.3V line as its own power supply – it looks a bit messy to do on a new piece of equipment, I've an eyesight problem, my only soldering iron may be too big for the job, all-in-all it's not really something I'd really like to attempt.

Is there a programmer I might economically buy to do this job once every 2 to 3 years? Is it likely I'll find a repair man with the right equipment to do the job economically? What should I ask one to make sure he has the equipment for the job?

[CJay]

Happy to mod a CH341 programmer for you, I think the programmer will support that MX25L800 without any drama but your main problem is going to be removing the chip and refitting it unless you're going to try and program it in circuit.

[physicsguy]

Thanks for the mod offer – I may well take you up on it.

I had the monitor for sale for spares or parts on eBay, but a repair guy I'd written to earlier, who lives about 10 miles or so away, suddenly replied to me saying he might be able to help. He was very busy – I don't know if there's a lull in the repair business in January like in many other businesses, but I said it could wait till then.

Since then, I've taken a closer look at the CH431A, which is probably cheaper to buy than the cost of getting the monitor to the repair man or vice versa. You can buy them supplied with a SOP8 clip connection, so you can program the chip without removing it from the board. The question is whether the surrounding circuitry will "dilute" the 5V down to something lower, more suitable, or whether there's a risk of damage. People have reported successfully using a CH431A for this job on this LG monitor.

If I can reprogram the chip still soldered into the circuit, I could practise with the spare mainboard I have, and if that seems successful, then the greatest problem I may have is getting the back off the monitor!

[CJay]

Thanks for the mod offer – I may well take you up on it.

Just send me a PM if you decide to, it's a five minute job.