S2000 door open MB problem?

[timd]

Reading a previous thread, it appears that my MPU bit the dust.  Had power glitches (3) in rapid succession.  I heard my two IGT S2000 slot reels turn, so I assumed they survived.  Later, saw that one of them had a "Door Open MB" error.  In the previous read thread, someone said, that if the door & bill stacker optics have been bypassed (I assume mine are), then the fault is with the MPU.  I reseated the MPU, Bill Stacker, Bill Reader and several connectors.  Turned the slot on and it worked....for about 30 minutes.  Then, the reels started turning and the Door Open MB error showed up again.   Left the slot off over night.  This afternoon, I turned it back on and it initiated properly, no errors!  Made one play and the slot errored with Door Open MB error.  No devices look cooked.  What area of the MPU should I probe to figure out what has failed?

[qbert]

What does the VFD say? Is it indicating a specific reel fault or does it change which reel faults. Or does it say random reel fault?
Check your coin battery voltage. You need to verify that the optics have been disabled because it sounds like they may be out of adjustment. That would also give you reel faults. Be sure the latch is all the way down when you close the main door.
 
Plenty of good information here.
When you have an issue with your machine please always start a new post explaining your machine's issue.

[timd]

No reel faults.  Coin battery (BT1) reads 3.0 v. VARTA 3.6 v battery (BT2) reads 1.1 v.  Is that any consequence?
VFD shows DOOR OPEN MB as stated in my O.P.

[sixcardmark]

Check the area under that green varta battery. The door circuit traces are under it. It is not needed for home use.  It can leak and cause the door open state.  If your BV door switch has been bypassed check the wires to see if they are connected, if not bypassed check the switch or bypass it. 

Your varta battery at 1.1v has probably leaked and destroyed the door traces.  Post a pic of that area.

[timd]

Thanks for the suggestion and about the VARTA battery not being needed for home use.  I'm going out of town today so I won't be able to work on it till Monday.  I'll post an update when I check the traces.  Thanks again!

****UPDATE****
As promised, I removed the VARTA battery.  Appears that one trace is probably open.  It is black compared to adjacent traces. The trace goes under U84 near the HEADER pin 16 (NOT device pin 16).  If someone can provide where this trace connects so I can check for continuity and to where I can place a bodge wire to fix.
Can anyone provide a schematic of this area, I'd appreciate it!

[timd]

photo

[sixcardmark]

Member lookes repairs these boards.  Hopefully he will log in soon and take a look at your pic and let you know what he thinks.

[lookes]

Yes. It's repairable.  From what I see it should have Door Open errors.

[timd]

Yes, I am asking where the 'black/burned' trace goes.  That is, what two points can I use to check for continuity of that trace and use to place a repair wire.  It looks like there is no part of the trace that I can solder to.

[Retro tech repair]

Im seeing damage to both the door and the comms traces.

[JethroP]

Did you ever get a schematic or someone here to help you fix yourself?  I have the same issue.