Arcade Otaku - アーケード オタク

Hi Guys,

I finally got around to burning my eproms with this legendary mpatou romset! Game runs perfectly apart from one issue;

I have an issue with my old bootleg board, it seems red has stopped working, I'm hoping someone can help a poor noob like me for any leads into where to look/replace etc.

Here's some pics of my issue and the board.

Cheers,
Grish

Hi

First thing you should do is cleaning the edge connector on the PCB : I personnaly use a cuetip with 90° alcohol, a friend o'mine use a rubber eraser, if you have an electric contact cleaner like KF, is great.

Then, I would check your adapter to see if the Red wire is still connected.

Please, do those checks then post here if it has worked or not.

Thanks mate,

I did clean the edge connector and test the harness/adapter OK.

Unfortunately I've made the situation a lot worse by attempting to replace one of the 74ls174 chips (local elec store only had 74ls174n but based on data sheets I couldn't distinguish between them?)

I managed to break at least one trace and tried fixing that with a little hack wire, but now I'm getting repeated GFX (top third section of screen is repeated in lower third)

Plus still no red

Why did you remove this 74ls174? Don't worry about the N at the end of 74ls174N

I traced the red line to it from the edge connector, it was as far as I got, then I also read somewhere that someone else replaced a 174 and/or 175 to fix similar issues.

Unfortunately I didn't realise I could have tested using piggy back method, but you live and you learn right?

Now you can try piggy packing to see if the new 74ls174 hasn't been damaged during installation.

mpatou, any idea what could trigger glitches like that on an original board?

for example:

starting with the sword before talking to the 1st guy:



random game overs:





glitches but game does not freeze











roms checked (also burned 70ns eeproms , did not help) , sprite rams reversed back to originals, psu powering the game is a meanwell with more than enough amps . I also noticed that if you do not feed the game 5.10+ volts then the music plays a tad faster - small change in speed but I can notice. You could leave it demo for hours and it would be fine, then it started doing this before the knight fight on level 4 , then it started doing it at the town, then it creeped on 1st level too...

Board is nice and clean, no bad soldering or weirdnes: https://i.imgur.com/AqiSkD2.jpg
for reference this is the back side of the sockets I installed for the 6x sprite ram ICs: https://i.imgur.com/bM2wDc2.jpg

any idea what to look? thanks!

Sprites look nice. As it's not only a display issue, I'd take a look around main CPU circuit (main CPU itself or associated ram IC).

thanks for the input mpatou! appreciate it!!
yes it looks like a cpu work ram issue?
do you have any idea which ram is that on the board? is it the 2x SONY srams at M1 and N1 ? or the K5 one?

The main CPU (z80 @ ic55)could be faulty too. Try to replace it.
Main CPU ram is ic93, next to main CPU romchips. It's not necessary the chip itself that is faulty, could be many things around it (LS244, LS374 etc...).
It's not easy to find what is wrong.

Thanks again for the info!
Yes many many things could be wrong, a starting point helps!
I'll report back when the culprit is found

Hi Mpatou and all,

Quick update:

Red is now working! So the original problem I had is now fixed. It was a dodgy resistor meant to be 100ohms, but was reading 1Megohms! - Swapped it out and bingo back came red!

However, the other problem that I somehow managed to introduce while stupidly replacing the 74174 chip is still there (I tried piggy back with new 174 and nothing changed), the top quarter or third of screen repeats itself in lower part of the main game play window, the "border" appears fine! The pics say 1000 words anyway...

I know it's nothing to do with the PROMS and I'm now suspecting RAM, take a look at pics and if anyone has any clues please chime in!!!!!

Cont...

This next part is VERY interesting, the problem doesn't show up on the credit screen if you credit up BEFORE the game demo runs....:
After game demo has ran:

can anyone with an original board tell me what value is the resistor in this pic? ?(or get a good one so I can see the colors) , it's the patch resistor above IC57
Thanks!!!

Hello

I think it doesn't matter, it's here just to provide 1 as logic value while not creating a short-circuit.
If you need to replace it, put something like 2Kohm or 4Kohm.

^ thanks mpatou!

ok back with another question.... anyone knows what these jumpers on the System2 boards do?





more importantly, what are the correct settings for Monster Land?
I know there are various System 2 versions, I have 171-5303-01 (original choplifter) and 171-5305 (no idea if this was an original wboy2 or some other game)
thanks!!!

mpatou wrote: ↑January 9th, 2019, 12:58 pm You've got a private message

Can you send me the order of rom files to burn to eproms. I have a bootleg board also.

I forgot to report back, solved the issue months ago... It was the main Z80 - replaced it and all is fine again

Just out of Interest, I have a ChopLifter System 2 board, Is it just a case of downloading the decrypted ROMs and burning to get it converted?