EzoFlash 4v5 with 29F800 chips - huge problem

[bajticzek]

Hey guys,
I'm having trouble reading/writing EEPROMs 29F800 (AMD and Fujitsu). I have built double sided EzoFlash 4v5 and TSOP48_B2 adapter. I tried to read and write 4 eeprom memories (1 Fujitsu branded and 3 AMD ones) and I was succesful only in one attemp.

I tried to do the classic sequence of tasks:
1. Get chip ID, 2. Read it, 3. Verify and save the buffer to file, 4. Erase the chip, 5. Blank check, 6. Load another file into buffer and write the content to the memory, 7. Verify.

The problem appears at random moment. I simply cannot even get the chip ID. But I'm sure the chips were fine. I tried two of them and failed after erase->blank check, chips are returning 0xFF everytime. The third one (AMD) went fine, hence there were some write errors, so I had to write the data 3-4 times (with erases between them). But in the end, this one chip was succesful to write (verify was ok). And last one - the same old song again. I could get the chip ID, read it, erase it, but after that - no chip ID, no communication whatsoever.

One thing that is strange - I randomly could pick up the chip ID, but it was in 1 out of 100 attemps (I was clicking the ID button like crazy). But after that i gave up, desoldered "bad" chip and tried with a new one.

I tried the HW test (with jumpers 1, 3, 5, 6 and 97) and each pin of programmer is working fine, the connection between the programmer and adapter is fine too. I also tried to measure the "test points" according to the pdf with the image of them and all voltages were correct. Also I'm not using any LPT extensions cable and I'm powering the board from laboratory power supply. Switching between ECP and EPP didn't make any change.

I'm really lost and don't know what to do next. I hope the programmer didn't burn my chips for no reason.

If you could point me into the right direction, I would be very grateful.

[Ezo]

Here are a lot reprogrammed 29F800.
Stable get ID reply is first step before start any other command !
Run 4v5 Test H/W for all pins one by one.
Check chip soldering on tsop48b2 (clean flux, check bad solderings)
Having random valid ID reply - try again with options 1) removed Jp6 2) voltage 4.3 set Jp2Jp3
3) avoid non-filtered power supply ,awoid pulse type (without normal trafo) power supply