Luis' Build

[lrodriguezrullan]

Thanks. I will resolder the SIMM socket and try pushing different parts of the board.

Yes. I always get the same error.

[exxos]

Also check resistance from 0v and 5v to all DRDx pins on the simm. Make sure no low resistance values there.

Also check the buffer ic where DRD8 passes looks soldered OK.

[lrodriguezrullan]

I am taking another look at this while on vacation.

The diagnostic cartridge returns this over the serial port:

<0D><0A>I1 RAM/data line error 0000000000000000 0000000100000000 000008

I checked resistance from 0v (pin 1) and 5v (pin 10) to each of the DRD pins on the SIMM socket. There were no low resistance values.

I double-checked the solder on the SIMM and pushed different parts of the board while running the diagnostics. I also tested with a different SIMM. The results were the same.

Not sure where to go next.

[exxos]

Looking at this image viewtopic.php?p=90359#p90359

Have you checked either side of that track on the simm and check the entire track length for continuity.

Also have you checked for sold the blobs on the top side of the motherboard underneath the simm socket?

[lrodriguezrullan]

Yes. I was able to trace continuity all the way from the SIMM to the MMU, skipping the 74LS244.

Can you tell me more about what to look for on top of the motherboard underneath the SIMM socket?

Thanks.

[exxos]

Can you tell me more about what to look for on top of the motherboard underneath the SIMM socket?

The pins which come from the bottom of the simm socket, there is a few mm of legs showing which are on top of the motherboard... If you applied to much solder it blobs across the pins and shorts them.

[lrodriguezrullan]

I do see some solder blobs. I will take a closer look. Thanks!

[lrodriguezrullan]

Can we use the multimeter to detect if these blobs are shorting the pins?

[exxos]

Can we use the multimeter to detect if these blobs are shorting the pins?

Yes. You need to follow the image I posted earlier as some pins are connected together.

[lrodriguezrullan]

I apologize. I can’t figure this out. It is over my head.

Is there someone I can ship my board to, than can try to fix it? Of course I will pay him. Thanks.