With the very limited info provided, I suspect a connector is loose. It would be less likely for a machine to suffer a board failure or other major issue while turned off. Try this: Find the connectors associated with the switch matrix and unplug-the-reseat them. J206/J207 I think. (Look for Green-Violet)

First, confirm that ALL EIGHT of the switches shown in the switch matrix for column 7 are non-functioning. IF ANY ONE of them ARE working, then you have a simple playfield wiring break. Under the playfield, you likely will find a GREEN-VIOLET wire that daisy-chains from switch to switch that has become broken or pulled. It happens for various reasons, like raising or lowering the playfield. If NONE of them are working, then....

Power off machine and unplug.

The next step I would try is use an OHMMETER to verify the conductivity between the MPU connectors for column 7 (green violet on pin 7 of either of the connectors, J206 or J207) and each of the switches in that column. Start with one probe on the BOARD on the driver chip, Pin 12, and use the other probe to confirm it has connectivity to the J206/J207 pin 7 on each. If you confirm the driver chip to J206/207 is solid, then keep your probe on the connector Pin 7 and from there touch ANY switch below the playfield (identified in the row of switches matrix). Refre to the schematic listed on IPDB and the Switch Matrix. You will see that ULN driver pin 12 feeds J206 and J207 (which are on top of each other on the board) but focus on J206 as it feed the playfield. (Each of those connectors has a green-violet wire on pin 7 of the J206/207). Follow that one from the ULN pin 12 on the chip thru the connector to the switches. This feels like a broken wire or similar. It's possible the ULN driver chip on the MPU is failed, but less likely.

uln-fh (resized).JPG

U20 on the board. Circled in RED on the image

u20 (resized).jpg

And if you find connectivity all the way from the switches to U20 pin 12, then YOU MAY BE LUCKY and find that U20 on your MPU is a socketted IC and can be easily replaced with a ULN device. (Socketted IC will be all that is left once connectivity is confirmed.)

J206/207 have all 8 matrix inputs. Can you find the other 7 columns on seven of the U20 pins? That will confirm you are doing it right.

Also, With the closeup pictures, the card itself seems to have battery leakage??? That would explain a lot. If so, may be time to pony up a new card.

Alkaline damage to the MPU. Send it out for repair.

Columns are on U20 via J206/207, Rows are connected to U18 via J208/209. That means you won't get any connectivity to J208/209 if you are checking U20.

I think we are all suggesting (after seeing the pictures you added) to get a new MPU board and swap the ASIC/ROMs over. WPC89's are maybe $225 on Ebay.

Repair is often cheaper than replacement. Not always. It depends on the extent of the damage. IMHO: this board has wide-spread corrosion and also has evidence of previous repair. Contact ChrisHibler and see if he is willing to repair the board.

The areas I can see from the images you provided are in red. The inductor with black discoloration is a particularly bad sign for me. The corrosion also appears to have entered the connectors and that's something you will likely have to replace yourself (or get a technician to do it for you if you are uncertain about how to proceed).

I have an available (already built) reproduction WPC-89 CPU board if you are interested. I would start with Chris Hibler though. Repair is often cheaper.

01.jpg

02.jpg

I can see corrosioin on the top of the connector at J209. Look through the back of the rectangular hole on the connector. That green stuff is a problem.

Once the MPU is replaced, you will need to repin that connector.

J207 may have the same issue.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

Did you change the connectors as well ? Because there was a lot of corrosion inside them which might lead to new issues eventually.

Hopefully the cables are long enough so that you can cut off a piece of wire , strip it , use a crimper with crimp pins to just "squeeze" a new pin to a wire and then push it in the new connector. The secret is to strip just enough so that the pin will crimp both a piece of the wire and on another tab it crimps the insulation to hold it firmly in place.

You will want to get new shell and the pins. The shell itself provides the mechanical stability. They are a buck or two. It's enough work and cheap enough that it would be silly to save any of the parts involved with the damage.

The shells, housings, are actually called connectors.

Count the number of pins you need and order them specifically or get long 24 pin ones and cut them to suit.

Get the .156 trifurcon pins and connectors, connectors can be cut to fit with diagonals if too long, get keys too:

https://www.greatplainselectronics.com/products.asp?cat=81

Get this crimping tool, with a couple clicks of the ratchet it holds the pin for you for very easy installation of the wire. Get extra pins and practice crimping on some scrap wire before you start. Its very easy but you need to do it a few times to get the feel of it. Get scrap wire at Home Depot or autozone. AWG 18 and AWG 22 size wire use the same connectors:

https://www.amazon.com/IWISS-Professional-Compression-Ratcheting-Wire-electrode/dp/B00OMM4YUY/ref=sr_1_7

Read a bit of this or print it out:

http://www.pinrepair.com/connect/

Ed at GPE is on pinside and is an excellent asset to pinball. He is continuously contributing to the community.

pinsider G-P-E