Grabbed this a few days ago from @deadmatty .. Not a massive fan of the game but I fixed one of this version (A7007) not too long ago (Link Here) and have another (albeit different pcb version - A8007) faulty one. So the thinking being I can either use the working one I have to help fix this one from Matt, or use the parts on this one to help fix the 8007 version one ....
PCB arrived in really good general condition, Matt did disclose it was missing a couple of LS367's and a couple of traces had been damaged in their removal. He also mentioned that those IC's had been removed because the game was not working with just garbage on the screen ... The top 367 had a small trace break and the bottom one the trace was still connected but flapping around. Made those traces good, popped in a couple of sockets with some good reclaimed LS367's and all connections tested good ....
Noticed a couple more issues on visual inspection ... corrosion on some chip legs here and there, isolated in patches though as if something corrosive dripped across the bottom section of the board at some point. The other thing that stood out as odd was the common leg of a pull up resistor array was not soldered through the board !!
The resistor array leg looked like it had purposefully never been soldered but I checked my working board and it's array's leg was soldered so I soldered this one up to match.
Most of the random IC leg corrosion scraped away easily so I hoped this wouldn't be a bigger issue down the line and powered up for the first time ...
As expected, a non booting game. Although the screen was slightly changing here and there, for a bit... as though there was something going on, but just a mess, and all in green !
A bit more of a visual and the 2 tile ROMS did not look great...
Again isolated corrosion in certain areas ... removed them both from their sockets and some legs just fell off both ROMs, sockets were not in great shape either. Replaced both the ROMs and the sockets, which changed things on screen a little bit.
At first just a load of Purple P's !!! ... Decided to check and clean all other ROM's. All checked ok and sockets in ok condition. All cleaned and put back in, then regularly got the picture above right every boot.
Game does not seem to be running ... Scope comes out and the 68000 cpu has good clock, Halt and Reset are held high, has LDS and UDS all toggling, data lines toggling, but nothing above A3 toggling on the address pins... Suggesting the CPU is running, but it’s stuck in a very small address range. Then realised the higher address lines do pulse on power up but go static after around 1-2 seconds. AS and DTACK continue toggling, and BR, BG and BGACK are all solid high so the CPU is not halted and not bus-erroring. It is actively executing something — just at the same address over and over. Spent a while tracing signals around CPU/RAM/ROM/Buffers looking for anything suspicious because I think the game isn't running but despite the address lines being dead from A4 upwards nothing stands out as obviously bad. I'm thinking of switching out the 2x 6264 work ram but before I do I get a bit lucky and everything falls into place ...While probing the CPU, again!, by accident I bridged a couple of data pins and the screen changed, I could see a bit of the game's title screen and then the attract mode running, all through a layer of random garbage ....
And this made it clear the game was running and it was actually a video display problem I had.. Through all the crap on screen I thought the sprites looked ok and whatever was causing all the corruption was the highest priority layer which is usually the character/text layer and in the case is the 2 tile ROM's I replaced earlier with new sockets. Knowing they were ok I scoped the 2x 6116 RAM right next to the ROM's used by the circuit, and the data lines looked very iffy ..
So I piggybacked both RAM chips and booted to what you see above right. That's the diagnostic start up tests and the boot was hanging on this earlier when the CPU was running but in a very small address range. soon as you bridge D3 and D4 (I think it was) on the CPU it snaps it out of the start up tests and runs the game!!
Replaced one of the RAM chips first which cleared up half of the corruption (below left) so moved on to the second one as well as both must be bad ...
Which cleared up all remaining graphics issues !! Game is now running solid, no sound problems, 100% fixed.
PCB arrived in really good general condition, Matt did disclose it was missing a couple of LS367's and a couple of traces had been damaged in their removal. He also mentioned that those IC's had been removed because the game was not working with just garbage on the screen ... The top 367 had a small trace break and the bottom one the trace was still connected but flapping around. Made those traces good, popped in a couple of sockets with some good reclaimed LS367's and all connections tested good ....
Noticed a couple more issues on visual inspection ... corrosion on some chip legs here and there, isolated in patches though as if something corrosive dripped across the bottom section of the board at some point. The other thing that stood out as odd was the common leg of a pull up resistor array was not soldered through the board !!
The resistor array leg looked like it had purposefully never been soldered but I checked my working board and it's array's leg was soldered so I soldered this one up to match.
Most of the random IC leg corrosion scraped away easily so I hoped this wouldn't be a bigger issue down the line and powered up for the first time ...
As expected, a non booting game. Although the screen was slightly changing here and there, for a bit... as though there was something going on, but just a mess, and all in green !
A bit more of a visual and the 2 tile ROMS did not look great...
Again isolated corrosion in certain areas ... removed them both from their sockets and some legs just fell off both ROMs, sockets were not in great shape either. Replaced both the ROMs and the sockets, which changed things on screen a little bit.
At first just a load of Purple P's !!! ... Decided to check and clean all other ROM's. All checked ok and sockets in ok condition. All cleaned and put back in, then regularly got the picture above right every boot.
Game does not seem to be running ... Scope comes out and the 68000 cpu has good clock, Halt and Reset are held high, has LDS and UDS all toggling, data lines toggling, but nothing above A3 toggling on the address pins... Suggesting the CPU is running, but it’s stuck in a very small address range. Then realised the higher address lines do pulse on power up but go static after around 1-2 seconds. AS and DTACK continue toggling, and BR, BG and BGACK are all solid high so the CPU is not halted and not bus-erroring. It is actively executing something — just at the same address over and over. Spent a while tracing signals around CPU/RAM/ROM/Buffers looking for anything suspicious because I think the game isn't running but despite the address lines being dead from A4 upwards nothing stands out as obviously bad. I'm thinking of switching out the 2x 6264 work ram but before I do I get a bit lucky and everything falls into place ...While probing the CPU, again!, by accident I bridged a couple of data pins and the screen changed, I could see a bit of the game's title screen and then the attract mode running, all through a layer of random garbage ....
And this made it clear the game was running and it was actually a video display problem I had.. Through all the crap on screen I thought the sprites looked ok and whatever was causing all the corruption was the highest priority layer which is usually the character/text layer and in the case is the 2 tile ROM's I replaced earlier with new sockets. Knowing they were ok I scoped the 2x 6116 RAM right next to the ROM's used by the circuit, and the data lines looked very iffy ..
So I piggybacked both RAM chips and booted to what you see above right. That's the diagnostic start up tests and the boot was hanging on this earlier when the CPU was running but in a very small address range. soon as you bridge D3 and D4 (I think it was) on the CPU it snaps it out of the start up tests and runs the game!!
Replaced one of the RAM chips first which cleared up half of the corruption (below left) so moved on to the second one as well as both must be bad ...
Which cleared up all remaining graphics issues !! Game is now running solid, no sound problems, 100% fixed.
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