BOARD 1
Bought blind from @Alpha1 a while back, made a brief start on this one months ago but then it got put to the back of the queue till now ....
No sign of life when powered up, just a black screen, making a bit of a noise when the larger daughter board was pressed, but other than that - dead ...
Had seen better days this one with evidence of trace damage/repairs, corrosion, dirt, flux, chip replacements etc on the solder side of the board .... a few highlighted !
and checking over the parts side of the board there were other areas of concern ...
The blown capacitor is in a bit of an odd place in the middle of the board, not near much other than a diode maybe? and suspected it could be part of the reset circuit.
The 54S04 chip was another mystery for a short while, I thought the piece of wire was just there to connect pins 8 & 11 because those pins had solder on them, but after looking at pictures online of this bootleg it was clear mine was missing a crystal here !!! Confirmed later to be a 20Mhz. I didn't have a replacement crystal at the time so put this board to one side and got on with other things !!
Fast forward a few months and I dig this out again yesterday ... replace the capacitor and add the crystal ...
I put the crystal flat against the board, rather than over the chip (like it must have originally been done). Much tidier this way and less chance the crystal being knocked and damaged. just had to connect one leg to pin 11 on the solder side to get the right connections.
Time to fire up the game again and see where it's at now ....
At first I thought I'd cracked it, nice easy one !!
But then got the feeling not everything was right. I have never played this game before (which is mad considering I'm a massive fan of the original Wonder Boy) so took me a minute to realise some sprites were missing ... Main character was fine but things like coins, enemies and platforms were absent ....
Time to check the ROMs .. and one of the mask roms (marked with a yellow sticker -number 7) was bad. reading different every time, but usually empty!
Seemed all the other ROMs on this board are from the japan bootleg version and 7 corresponds to 'epr11030.89' (a sprite rom !) so burned that to a 27C256 and popped it in pretty hopeful this would be the issue sorted ... and it was !!
All missing sprites now appearing where they should and everything looking good. Sound effects and music all present too so was feeling pretty happy with this, looking forward to having a play of it for the first time ! Just a bit of a hiss on the speaker and I had noticed the main 12v filter cap had also blown so I think, right I'll just tidy up the caps in the sound section to get this tip top before I have a play. And I did ... replaced a cap, straightened a few others up. All was looking good. Right lets turn it on, have a game ... and I did ... and I got this .....
What the F***
What have I done ??? I must've done something, it was fine 5 mins ago ... All I could think was I must have either nicked a trace or a blob of solder has pinged off somewhere and bridged some pins ... has to be something I've done. So I spent ages, and I mean ages checking for trace damage or stray solder blobs or anything else I might have done ... but couldn't see anything. Out came the scope, if I've lost a trace and therefore there's a missing signal I'll have to try and find it with the scope ..
Started with RAM and the 2x 6116 ram next to the main Z80 looked fine, moved to the 4x 6116 ram near the jamma connector, no idea what they are for. It was late, I didn't care I was annoyed. Saw a weird signal on one of the data lines .. Bingo I think ...
Looks like 2 different data signals competing ... this must be where I've bridged a track or something ... searched the board (again) in this area for clues .. but nothing ..
must be bad ram then ... took it out, in goes a socket and a replacement ... and .. nothing .. no different. 😡 got angry, went to bed, cursing myself for breaking a board literally 5 mins after fixing it.
Woke up with a fresh outlook. Right, there are some sprites still appearing totally normal on the screen. If that's the case then it must be a backgrounds/tiles only issue, ok so that circuitry is at the opposite end to the jamma connector , 3x roms and 2x 6264 rams .. scope on the ram and straight away got floating data pins, ... ok check under the board again here, still convinced I've nicked traces or something. can't see anything a miss. ok bad ram? both of them? can't be. grabbed a couple of 6264's from my stash and piggybacked both and fired up to this ....
Ok this looks promising, let's get this ram out, both of them, might as well socket both while I'm there. So I did and tested them both and one failed ...
tbc....
Bought blind from @Alpha1 a while back, made a brief start on this one months ago but then it got put to the back of the queue till now ....
No sign of life when powered up, just a black screen, making a bit of a noise when the larger daughter board was pressed, but other than that - dead ...
Had seen better days this one with evidence of trace damage/repairs, corrosion, dirt, flux, chip replacements etc on the solder side of the board .... a few highlighted !
and checking over the parts side of the board there were other areas of concern ...
The blown capacitor is in a bit of an odd place in the middle of the board, not near much other than a diode maybe? and suspected it could be part of the reset circuit.
The 54S04 chip was another mystery for a short while, I thought the piece of wire was just there to connect pins 8 & 11 because those pins had solder on them, but after looking at pictures online of this bootleg it was clear mine was missing a crystal here !!! Confirmed later to be a 20Mhz. I didn't have a replacement crystal at the time so put this board to one side and got on with other things !!
Fast forward a few months and I dig this out again yesterday ... replace the capacitor and add the crystal ...
I put the crystal flat against the board, rather than over the chip (like it must have originally been done). Much tidier this way and less chance the crystal being knocked and damaged. just had to connect one leg to pin 11 on the solder side to get the right connections.
Time to fire up the game again and see where it's at now ....
At first I thought I'd cracked it, nice easy one !!
But then got the feeling not everything was right. I have never played this game before (which is mad considering I'm a massive fan of the original Wonder Boy) so took me a minute to realise some sprites were missing ... Main character was fine but things like coins, enemies and platforms were absent ....
Time to check the ROMs .. and one of the mask roms (marked with a yellow sticker -number 7) was bad. reading different every time, but usually empty!
Seemed all the other ROMs on this board are from the japan bootleg version and 7 corresponds to 'epr11030.89' (a sprite rom !) so burned that to a 27C256 and popped it in pretty hopeful this would be the issue sorted ... and it was !!
All missing sprites now appearing where they should and everything looking good. Sound effects and music all present too so was feeling pretty happy with this, looking forward to having a play of it for the first time ! Just a bit of a hiss on the speaker and I had noticed the main 12v filter cap had also blown so I think, right I'll just tidy up the caps in the sound section to get this tip top before I have a play. And I did ... replaced a cap, straightened a few others up. All was looking good. Right lets turn it on, have a game ... and I did ... and I got this .....
What the F***
What have I done ??? I must've done something, it was fine 5 mins ago ... All I could think was I must have either nicked a trace or a blob of solder has pinged off somewhere and bridged some pins ... has to be something I've done. So I spent ages, and I mean ages checking for trace damage or stray solder blobs or anything else I might have done ... but couldn't see anything. Out came the scope, if I've lost a trace and therefore there's a missing signal I'll have to try and find it with the scope ..
Started with RAM and the 2x 6116 ram next to the main Z80 looked fine, moved to the 4x 6116 ram near the jamma connector, no idea what they are for. It was late, I didn't care I was annoyed. Saw a weird signal on one of the data lines .. Bingo I think ...
Looks like 2 different data signals competing ... this must be where I've bridged a track or something ... searched the board (again) in this area for clues .. but nothing ..
must be bad ram then ... took it out, in goes a socket and a replacement ... and .. nothing .. no different. 😡 got angry, went to bed, cursing myself for breaking a board literally 5 mins after fixing it.
Woke up with a fresh outlook. Right, there are some sprites still appearing totally normal on the screen. If that's the case then it must be a backgrounds/tiles only issue, ok so that circuitry is at the opposite end to the jamma connector , 3x roms and 2x 6264 rams .. scope on the ram and straight away got floating data pins, ... ok check under the board again here, still convinced I've nicked traces or something. can't see anything a miss. ok bad ram? both of them? can't be. grabbed a couple of 6264's from my stash and piggybacked both and fired up to this ....
Ok this looks promising, let's get this ram out, both of them, might as well socket both while I'm there. So I did and tested them both and one failed ...
tbc....
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