MPU200 flashes twice then hangs

[deep six]

I knew I should have stopped earlier before I re-pinned the MPU board.
After Ken changed the U1 chip in my soloniod driver board and all was working fine I should have just shoved the board back in the game and started playing.
But aww no, I had to keep going.
Now that I have re-pinned the Sol board, and the MPU board, fitted a capacitor battery, plus fitted all new molex crimp connectors and put the damn thing back together it now refuses to start up.
At least it isn't blowing the playfield fuse anymore which is a small consolation.
So I plugged it back into the mains, waited for the thing to boot but it only got as far as two flashes.
I checked for 5v at TP5 and 12v at TP2 on the MPU board which I have OK, well actually have 14v at TP2 which I think is still OK.
One thing I think may be an issue, and I only just read about this somewhere else on this forum is the EPROM at U6 had a small red sticker on it which had half peeled off.
I had the board out in the sun while I was giving it a coat of clear lacquer after I fixed a small amount of corrosion and when I got it back inside I noticed the loose sticker and thought "Oh Crap"
Figuring it might still be OK as some members had reported exposing eproms to direct sunlight with no adverse effect.
But now I'm wondering if this may be the cause for my "no boot" condition.
Any suggestions please???

[ddstoys]

Try re seating your 5101 ram I think that's what 2 flashes means?

[deep six]

Hi DD

Just tried reseating U8 (5101) crossed fingers but still hangs at second flash, Bummer

[Boots]

Extract from Pinball guides:

Third Flash Completed:
The Fakers Guide: a third flash means the U8 5101 RAM is good. No third flash means U8 (5101) or its socket is bad. Not on Stern M-200 board the third flash is also testing the U13 RAM (5101). Additionally a bad 6800 processor at U9 can also only allow the MPU board to flash twice and stop (no third flash.) I know that sounds strange, but I've seen it happen. So if you know the 5101 is good and there's no battery corrosion, try replacing the 6800 at U9 with a known good version.

You may have to replace the sockets as well as the ram.
U8 is right in the corrosion zone.

[deep six]

Well Guys, I got that problem sorted. I made up a bench tester for the board comprising a 5v / 12v donar power supply out of some sort of machine (found it at work while scrounging around).
I studied the article on pin wiki about making your own bench test jig.
Only thing I wasn't too keen on with their setup is they used alligator clips connected to the relevant test points on the board to power it up. I decided to go a little further and after tracing the test points back to the correct pins on the J4 connector I made up a 3 wire plug (5v, 12v and ground) using a .100 molex connector.
Also added a key so it couldn't be plugged in the wrong way.
Plugged it in, powered up the board but initially it wouldn't boot, eventually I pulled the 5101 chip back out ( had removed it before from the board mounted in the machine)
Found I had bent some of the pins on my previous effort so straightened these out and put it back and she booted up fine, at least 6 flashes as I didn't have a 43v power supply for the solonoids.
Bunged the board back in the machine but it refused to boot.
To cut a long story short it ended up that I had plugged the ribbon cables in arse about and this stopped the board from booting, I only discovered this after disconnecting every plug except for J4 and working backward from there, finally after much head scratching and trying alternate combinations I happened upon the right one and she now works.

[Steevsee]

Well done on getting it going. 

[ajlaird]

Well done, it is very satisfying to get these things sorted yourself.

[goodolddays]

Good work 

[Strangeways]

Well done getting the board to work  The test fixture will come in handy for future repairs.

[JRK1971]

Well done, it is so common to overlook the simple fix/ problem looking for a bigger problem. I've done that so many times it not funny.

[goodolddays]

Well done, it is so common to overlook the simple fix/ problem looking for a bigger problem. I've done that so many times it not funny.

Me too !