Another board on the bench from my friend Enrico, this game is also known as Dark Seal 2 and it has been released by Data East on 1992.
The board is experiencing several audio effects issues from jerky sound, unstable volume and sometimes a strange kind of “motorboating” sound … it’s time to take a deeper look at the board!
These symptoms are typical and they are usually generated by one or more bad capacitors on the audio amp circuit, the power amp is a Toshiba TA8205. Here is a close up of the audio section of the board:
Looking at the solder side of the pcb we can quickly spot few loosen connection of some capacitors that should be reflowed and a totally broken solder pad, the first on left.
I fixed the missing pad with a jumper wire, it should be connected to the ground plane but it’s on the component side of the board, the via is damaged, so i found an alternative ground connection point and patched it.
I also removed all the capacitors and checked them against my tester, two of them, the big ones on the outer ends, must be replaced they are gone out of specs over the time.
I removed and checked all the capacitor on the audio section and i found several poor or loosen connection so they must be all reflowed, here are the affected caps:
All the capacitors on red circles must to be resoldered or replaced, only the two on the yellow circles were in good working conditions.
Now it’s time to deep testing the game! 🙂
Another case closed!
This is the second board Enrico gave me for repair, a Data East game from 1990, the first chapter of the Dark Seal legacy, also know as Gate of Doom, here is the PCB:
After a quick and dirty test, the board is experiencing several issues, wrong/missed colours in the text layer:
The text is unreadable it shoud be bright white, you can see the issue also on this image:
All the text were black, and nasty jailbars were present on the back graphics plane, and as the demo goes on also the sprites plane were totally or sometimes partially missed, and the background reports wrong/missed colours too. You can look at these issues on the following picture:
I started investigating by the usual visual inspection of the PCB. A deeper look at the soder side reveals the first damage reported by the board:
A scratch cutted some traces, it was very thin and sharp so the issue can be fixed by removing the protective shield painted over them and by reflowing the traces with the soldering iron without patch wires over the board:
With my magnifing glass i looked also at the component side of the board, and with the help of a needle a spotted also some lifted pins on a custom IC, also the traces under the IC seems to be lifted but fortunately they were not damaged, so i reflowed them:
These fixes recovered, the text and background colours and the missing sprites ingame:
Now the text is ok, and the sprites and background too :
But, jailbars still there … so the board need further cares. Jailbars can be caused by several issues, a bad eprom, broken traces, broken logic, broken data buffers, and so on … i started looking and the maskrom where the involved graphics are stored following the data path with the scope. Probing around i should able to identify the right maskrom, usually you should look at the schematics, sometimes they are well documented also on the MAME driver source, but when these methods doesn’t work you should get hands dirty and use other uncoventional methods for the series … “don’t try this at home!”. But safety first! So don’t worry Enrico no harm has been done to your board! 🙂
I succesfully identified the maskrom where i must look at, and i found one stuck line on the 74LS273 latches near it on red square, probably this should be the culprit for the jailbars. So i go on and i looked at the solder side for connections to and from the suspicious latch chip with the stucked line:
These are clear signs of oxidation and/or corrosion, a closer look after the cleaning reveals a broken trace under the dirt.
You can see other damaged tracks on the left but they are in working order. There is not enough room to apply a safe and robust patch in place so i had to use a small wire.
It’s time to test the board again … i powered it up and …
Yeah! No more jailbars and the board is fixed! Another case closed!
… and now … “Go forth brave adventurers and may the gods guide you!” 🙂
UPDATE: looking at the board i found a damaged volume pot in working order but hard to adjust due to its conditions:
Probably someone has been used a screw gun against it in the past to pump up the volume! 🙂
I removed it …
and i replaced it with a brand new one!
I received three boards from my friend Enrico for repair, this is the first one a bootleg board of Legend of Hero Tonma:
Legend of Hero Tonma is a side scrolling platform game released by Irem in 1989 on his M72 hardware platform.
Powering up the board ends up with this scenario:
… a solid white screen on boot, so i had to start the troubleshooting by inspecting the NEC V30 cpu, an 8086 pin compatible CPU. Here is its pinout taken from its datasheet:
Looking at its control pins with the scope didn’t reveals anything useful to solve the boot issue, so i had to deeper investigate on the address and data bus. Anything seems to be healty except when i put the probe on AD0 pin 16, the signals look weird. So i’m pretty confident and removed the CPU from its socket. Doing this reveals a very loosen socket, so it must be replaced to prevent further issues. Once the CPU has been pulled off, i can spot 2 broken traces under the CPU, one of them goes to/from pin 16. I promptly fixed them:
The CPU socket wasn’t in good condition so i removed it:
… and replaced it with a brand new one:
Now i’m ready for the smoke test, fingers crossed as usually and power feeded to the board. I was greeted with a solid black screen, a sign that something has been changed, but the board is still in not working, but i lightly heard some kind of music coming out from the speakers, pumped up the volume, and yes, the board is running i can coin it up and start a new game, but it still playing blind.
Touching around the board restore temporarly the background and the sprites, so i had to spot the failure. It ends up with a loosen contact on the flat cable connector that join the the PCBs.
So i removed, cleaned and reflowed it on the solder side. I powered up the board again and …
Yeah! It works! Now it’s time to a deep test ingame! 🙂
Board fixed, another case closed!