Friday, 26 November 2010

Philips NEC SOPHO Ergoline D325 clock fault.

I got handed a load of phones,phone worked fine but the clock doesnt work on the display was the issue.

First I found the phone runs of a digital PBX not the normal analogue one in my workshop so no way to start testing immediately.

Plugged into a digital socket, it retrieves the time digitally from the PBX after booting, increments one minute, then stops ? other phones of the same model working fine.

I found a customer service manual for a similar model

 this helped a lot, got me into service mode with password 12687, the service codes for the similar model were not all the same, working from 00 to 99, service code 28 feprom test would fail.

I found you could power it on the bench with 30v, I gave up looking for pinout of the connector and just measured the connector when plugged into the exchange ! This allowed to run the diagnostics without being plugged into the exchange. However with nothing to talk to the phone does not attempt to retrieve or display the time. In the pic brown is 0v, yellow 30v.

Inside the phone there was no RTC, a mcu, a transcoder, ram, flash ram and logic. feprom fail was the clue, I swapped the application flash eprom with one from a working phone, no change, swapped the boot eprom and bingo, code 28 passed and the clock worked.

The flash chips were faulty, failing to verify after being read.

Found an excellent desoldering technique for plcc packages on youtube, this helped the bulk desoldering no end.

I performed it with regular low temp solder ~270 degrees but have ordered some of this chipquick solder for future use, it looks very handy.

Purchased 4Mbit flash eproms, programmed with a good dump. Twelve phones in all faulty from new. (no warranty option as they had all been in storage for a while).

Chip out.

Newly programmed chip in.

Success !

1 comment:

  1. I really appreciate your professional approach. These are pieces of very useful information that will be of great use for me in future. Thanks for it.

    Nec phone Programming