VN 808 Help with OSE $12P V112

[starlight]

Hey Antus,
OK Now we're definitely getting somewhere!! - I am indeed using the 28c256, not the 27c256

So this explains everything - the pin outs are different that's why I was shocked to find the pins connected in such a way, I was thinking this will never work - but after being enlightened by your advice and investigating further into the PCB of the ECU, this all makes so much sense.

I stupidly assumed this was the correct pin out version of an EEPROM to use (had some spare from an old totally unrelated project)

Of course this works with the 16k bins, so long as they are stacked...and explains why a 32k bin that actually requires all 32k address locations fails.....

Thank you everyone for your suggestions and advice, I really appreciate it!

I'll get back to the drawing board now, and either obtain a 27c256 and rejig my programmer to suit - or, perform the creative wiring you suggest on the ECU.

I will report back once I have done either option with my results, but that won't be as quick as my current responses.

Thanks again all, happy we worked this out!!

[antus]

Good to hear. The 27c256 is not an eeprom, I was just using it as a reference for pins on the ecm. Ive used winbond and sst in the past but they're hard to get now, and in the past ebay has been flooded with forgeries that dont work properly. I dont know if this is still the case. Your often better with chip pulls from recycled computers. I think patching the memcal carrier under the chip for the one you have will be quicker, easier, and likely work well enough while you wait for more chips to arrive.

[starlight]

Ah yes, of course it's an EPROM not an EEPROM, I was getting ahead of myself with the excitement of finally having the problem identified.

You are absolutely right, regarding patching the carrier - That will be my first step in addressing this.

I have had issues with ebay gear - even lately - kind of a hit and miss so I prefer to avoid if I can but that's not always possible.

I know these EEPROMS work and work well - so memcal carrier patching here I come

[starlight]

UPDATE:

We have success!! Chopped half the leg off from the EEPROM SOCKET PIN 1 (A14), ensuring it makes no contact with the memcal adapter - soldered jumper wire from this half leg and ran it over to the memcal adapter's pin 27.
Removed the pin from the socket on pin 27 altogether so that it (Write Enable on a 28c256) makes no contact with the memcal adapter.

And powering up the ECU on the bench (too cold out right now) the "Fan" is not coming on and the CEL Flash procedure is working and giving me code 12 - SUCCESS!

Thanks yet again to everyone and Antus for the pickup which may have had me stumped for quite some time!!

[vlad01]

Yay!

[antus]

excellent, good to hear!