anyone seen (and fixed) this mr do pcb problem

[kcorcoran]

i have an original Mr Do PCB. When you boot it up you see everythign on the attract screens EXCEPT the mr do and monster sprites.

when you coin it up and do a 1 player start you get the first few nots of the intro music.. (still no mr do or monster sprites) and then you get the end of screen music and it auto advances to the next scene.

ran the self test on the board and it doesn't throw any errors.

adjusted the voltage to dead on 5v.

removed and reseated all the socketed chips.

visually checked all solder points on the back of the board and there's no corrosion or damage visible.

one of the rom chips has the IC window exposed (the others have stickers on them) so i'm wondering one of the roms could have been erased if this was stored in direct sunlight, etc.

if anyone has any ideas on trouble shooting this to get it running.. i'd appreciate it. i purchased this on ebay as "100% working" and of course it's not. the seller won't do anything for me so i'm just trying to get it going before i call it a total loss.

thanks.
keith.

[paigeoliver]

If you aren't a board wiz then I would suggest buying another WORKING Mr. Do! and chipswapping until you can rule out socketed chips.

Also, try the voltage higher, I have encountered some boards that need a bit more than just +5.0

Also, I like to check the voltage on a chip WAY FAR AWAY from the edge connector, you might have +5 at the connector, and be down to 4.2 by the other side of the board.

[MonitorGuru]

Guesses in order of probability:
- Graphics EPROM chip bad
- Controlling chip(s) for graphics eprom
- Ram bad
- Controlling chip(s) for ram bad
- too low voltage

While an eprom may have it's window exposed, normal storage, even for 20 years has a high probability (95%?) of NOT erasing it.  It takes multiple weeks/month in BRIGHT outdoor sunlight constantly to even have a chance at erasing an eprom. It requires special UV rays that normally arn't around inside a home/business to trigger the change (basically germicidal UV bulbs--not typical UV like from blacklights or what makes it through glass)

Yes, it can happen, but that is a very low likelyhood.

[bjk7382]

when you coin it up and do a 1 player start you get the first few nots of the intro music.. (still no mr do or monster sprites) and then you get the end of screen music and it auto advances to the next scene.

You have a working PCB, it is just in the automatic screen renewal mode. Look in the manual for the dip settings for SW6 on "Dip Switch A"

All you have to do is turn SW 6 of Dip Switch A to the ON position

The manual can be found Here