Brought a few of muddymusic’s PCB’s back with me from the recent Play:Expo. One of them was an original Willow PCB set.
The original fault was some lines through all the graphics but when I got it home there was nothing at all. I found with a little flexing of the B board then the game would run so I set about replacing the sockets that I know are quite unreliable in their old age. This didn’t make any difference.
I started checking the connectors that connect the B board to the A board and found 2 pins on CN2 that had no continuity through. These corresponded to A0 and A1 for the program ROM’s so that would explain why it wasn’t booting. Luckily Ive amassed a lot of CPS1 boards over the years and desoldered a 32 pin connector from the donor board and the Willow board.

This is what I got

The jailbars are back.
Luckily, I was expecting the C board to be broken before I got the game so I had modified the program code to use a B_21 C board instead.

This seems to now work fine but more testing will need to be done. This will most likely do until such time a new Willow C board can be found.

Got this fairly cheap from eBay.
Didn’t really know what I was getting but was described as have a chip missing. How bad can it be??
Answer: Very bad.

On getting the board and doing my visual inspection I quickly located the missing chip.

Yes that’s right, an 82S131 PROM. NOTE: the above picture was taken AFTER cleaning up. The chip was forcibly removed and had several legs still remaining in the board. It was also a mess underneath.

Now as my programmer supports this chip I wasn’t too concerned but after paying over the odds eBay prices several times trying to find one that was actually blank only to find they were all used it became clear that I wasn’t going to obtain one easily.
Enter Steph at HobbyRoms. My savior. In a little over a week I had the new chip in hand and already programmed with the correct data too.

Back to the visual inspection. There was a bit of damage to several changes underneath that would obviously need cleaned up and patched.

I fitted the new PROM and patched the 3 broken lines and fired it up to test.

A green screen. All was not lost at this point as the game could be coined up and played blind.
I probed the newly installed PROM and found the chip enable pin was not connected to anything. This pin is grounded (enabled) constantly and it looks as though it picks this ground up via a ground plane in the middle of the PCB. As this was one of the holes that was badly damaged from the old chip removal I found it had not made a good enough contact when I installed a new socket. A lot of solder later and that has now been sorted.

Fired it up for another test.

Getting better but not quite there.
Whilst probing around the patches I made I found an additional 2 pads that were unconnected that I originally missed. Patching these fixed all issues and the game is fully playable.

I actually really like this game and think its very good for its age. As an added bonus it was also an undumped version so its now added to MAME.
Massive thanks to Steph at HobbyRoms. Without his help this board probably wouldn’t have been fixed.
I would also like to add a note to any sellers of bipolar devices on eBay. At least put in a little effort to check your goods before selling at an inflated price. I get the impression most of them don’t even know what they are selling.

Ive decided its time to make a start on the huge back log of repairs that I need to get finished.
Today Snow Bros was on the cards. It was a fairly recent purchase but as I really like the game it was first on my list.

Board boots up and passes its self tests but had big graphics problems.

Cant tell from the pictures but the screen is also flashing.

This board is tiny so I started looking for RAMs that weren’t program or sound related and shorting a couple of data lines together. There is a bank of 4 41464 RAM chips in the bottom left corner that would appear to be screen RAM.

First off I found the /OE on the left hand 2 were shorted to ground so I desoldered them. At some point a track had burnt out and was shorting against the ground pin above it. Removing this short gave me this

Much better, the colours are now sorted but the screen was still flashing and the graphics on the title screen left trails of the image. I checked the RAM chips I had removed and found a dead one.
I just went ahead and desoldered the other 2 RAM chips. Again, one was good and one was bad. I replaced these chips with an 81464 from a scrap board.

All working now. Ill have a game on this later.