Viper Phase 1 graphics problems, need help from above :(

[Skykid]

FFS.

I have a VP1 USA region that I literally just sold yesterday and on taking it out of (very carefully packed) storage, I've got graphics issues on boot.

I've tried it on my Supergun and Egret II and the problem is the same. I've cleaned the edge connector, opened the case and taken out all the socketed chips, cleaned the pins and put them back again - nothing helps.

The weird thing is, it's kind of a jail barring issue but certain aspects of the graphics are fine, such as the "winners don't use drugs" screen and the Viper Phase 1 screen shown below, and certain parts of the graphics such as bomb tally, score and continue countdown.





Everything else is obscured:









The sound is fine and it plays fine. I know that VP1 has a weird refresh rate (not recognised by my XRGB2+), but I've got the same problem across both supergun and cab and can't think of any other way to fix it.

It's a bummer because it's kept safely in storage, standing upright with no pressure on the board.

Any help is much appreciated!

[PC Engine Fan X!]

I've got a USA region SP1 mobo with a copy of the same Viper Phase 1 U.S.A. cart & it works just fine. The RTC battery needs to be replaced soon considering that it's the original one when it was first manufactured back in 1994-1995 and distributed by Fabtek arcade distributor stateside.

Perhaps sourcing another working USA region SP1 mobo to see if it's the cart that's acting up or it could be the mobo itself.

Running the USA region SP1 mobo with VP1-U.S.A. cart works just fine with an XRGB-2 (the non-plus variant) upscan convertor.

PC Engine Fan X! ^_~

[Skykid]

No one got any ideas on this?

[grobda]

tried tweaking the 5v? tested the romboard with another mobo? looks like a pcb fault from the pictures, affecting the background tilemap and sprites, dont know enough about sp1 to guess really.

[Skykid]

tried tweaking the 5v? tested the romboard with another mobo? looks like a pcb fault from the pictures, affecting the background tilemap and sprites, dont know enough about sp1 to guess really.

Thanks for the info. I've tried tweaking the cab voltage yes, but unfortunately it doesn't seem to do anything for it. I sort of wrote off voltage as I know for 100% sure that my supergun and cab have power supplies running at slightly different voltages (the supergun can be temperamental), yet it performs the same on both setups, even after tweaking the cab voltage.

So is this type of graphics garbling concurrent with pcb faults? And are we talking something that extends beyond re-burning a rom?

I will try to get the cart tested on another US mobo as soon as possible, I believe Spadgy has one so he might be able to help.

[grobda]

doesnt look like an eprom, more a graphics ram/buffer/tilemap generator fault. could be as simple as a dry joint or two but you'll need to go at it with a logic probe and some schematics really.

[Skykid]

doesnt look like an eprom, more a graphics ram/buffer/tilemap generator fault. could be as simple as a dry joint or two but you'll need to go at it with a logic probe and some schematics really.

Don't know how to do.