R-Type Leo / Irem M-92 graphical issues

[parodius]

Hi

I recently received a Japanese R-Type Leo M-92 board.
When I first tested it, it was working fine (for 10-20 min) with my Sigma AV5000 supergun.
Then a few days later (yersterday morning) I decided to play with it a bit, I plugged it to the supergun, turned it on and let it run in attract mode for a while.
10-15 minutes after booting, a whole part of the graphics disappeared : all the sprites and writing in kanji/kana during the attract mode, as well as the "R-Type Leo" logo on the title screen, which now shows only the blue and green/yellow wavy lines which are normally behind the logo.

I turned it off and on several times, checked the voltages, to no avail. Sprites still missing and weird logo screen.
Reading on the multimeter :+5.09 -5.14 +11.78

I contacted the previous owner who told me he never encountered this issue.

This morning I tried the game again, and to my surprise the sprites were back, but just for 10 minutes and then they stopped working again...
In the afternoon, I tried it on my New Net City with Jamma adapter (the one from River Service) and it showed the same issue.

Note : the RAM/ROM checks at startup show "OK"
And I can't perform more thorough tests than RAM/ROM when setting on the dipswitch #8, like those described for In The Hunt :
http://www.mamechannel.it/files_free/ar ... nthunt.pdf

And I don't have any other M-92 game to try a mobo swap.

So, anyone has some experience with that king of issue on an M-92 ?
Reading about similar pb on different hardware, could it be because of a dead sprite RAM IC ?

Some pics :




Thanks

[parodius]

Restarted Leo tonight, it's working again.

I just found an interesting piece of information from system11's repair log regarding the J3 jumper on M-92 mobos.
Checked mine, jumper's there, in the 'B' position. Re-seated it in case there's a bad contact. Sprites still working right now.

[parodius]

Ah ah. A bit more of googling points me to this thread where someone experienced exactly the same issue.
http://shmups.system11.org/viewtopic.php?p=441980

[system11]

Yeah that's what I was going to suggest - reseating the board connectors. The jumper only affects sprites being there or not (completely missing).

[Gamesmonkey]

Many thanks for this information as my In The Hunt has no sprites and plays blind.
The jumper block was very loose at J3 so I ever so slightly bent the pins apart to make them tighter and now works perfectly.

ALSO ANYONE WITH A M92 MOTHERBOARD CHECK THOSE CAPS!