I installed nvram on 7 pins today (totan, mm, ijpa, hurricane, cc, ww, and DM). All went well with the exception of DM.

When I put the MPU back in a stupidly connected the ribbon cable from Aux PCB Assembly to J201 and the ribbon from the dmd board to the aux PCB connector on the MPU.

When I fired the game up, behavior was obviously weird. I turned the pin off and checked my ribbon cables to double check/reseat my ribbon cables still not realizing that the aux/dmd ribbons were swapped. Turned the pin back on and there was no activity at all.

Corrected the that mistake but now no joy.

MPU top and bottom leds are solid and middle led is now blinking every second or so.

Now I don't know if I made a mistake with the NVRAM install or damaged a board with the ribbon swap. Swapped NVRAM chip with a known good chip as well.

I clipped the old ram at the chip and removed the pins one at a time, desoldering with my hakko. There are no solder bridges and the pads were nice and clean on both sides before installing the nvram.

W3/R93 are correct.

Currently going through all of our pins for battery elimination (30 or so to go).

Fails with no ribbons connected.

Since the consensus seems to be that the ribbon swap would not damage the MPU I will start continuity tests on the nvram socket

Pin had 62256 and installed 6264. Removed W3 jumper and put a 1.5k resistor at R93. Already did a continuity check for a solder bridge. There is none.

First off, I want to thank you all for offering help. I could just drive the boards over to Chris H's house but would rather learn by doing.

Pictures as requested.

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Traced out the sip sockets and this is what I have. I took a pic of the underside of the cpu and flipped it so that it matches as if you were looking through the board.

20 on the sip had no continuity to the solder spot marked 20 between the cpu and nvram. Corrected that.

10 and 18 are toning together... correcting

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Ever so lightly rubbed a nylon point over the trace running between 18 and 19 because 10's trace runs through there and rubbed it between 10 and 11 because 18's trace passes through there.

10/18 are separated now.

Testing the board...

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Still no joy. Tried known good nvram.

Found this in another thread.

So I’ve done 14 nvram installs in the last couple days and the first 11 went without a hitch…. The last 3, what the hell!

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I’m alternating troubleshooting CPU’s and remodeling our master bathroom

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Ok, I set the failed NVRAM installs for DM, ToM and Scared Stiff aside and pulled the MPU for AFM.

Did the installation on AFM

Clipped the ram leads,
Removed each leg one at a time and inspected to make sure I didn't pull a pad or through hole.
Cleaned it up
Toned front to back and to the ROM and ASIC.
Installed the sips

Absolutely convinced this is my best nvram and solder job ever I installed the ram and put the MPU back in AFM.

FAILED AGAIN!

That's four in a row after a string of success.

So I pulled the NVRAM out of a previous good install (IJPA) and tested each MPU again

All of the MPU's are fine.

Bad NVRAM new out of the package. I guess I should reconsider what I mean when I said tested with a "known good" component (NIB isn't known good)

Thank you all for your help, upvotes for everyone.

Marco

Yes, all ramtron ic's

I never updated this.

Defective nvram was the problem. Lock when lit replaced them no questions asked.

I converted all of our pins to nvram