Sunset Riders glitchy sprites

[Kundi]

Hi!

I have a Sunset Riders PCB with a really strange problem:
Some of the spirtes (I think it's one layer) are glitching and disappear.
What's really funny: When I turn the 5V rail down, they come back for a short moment.

Here's some gameplay with the voltage dialed to 5V spot on

A little background information about the board:
I got the PCB in a non working state (bad 15B). Replaced that and got errors on roms 16K and 2F.
Also replaced these and now it runs and plays fine except the error mentioned in the beginning.

Has anybody seen this strange behaviour before?

If someone has an idea, I am grateful for all suggestions.

 

[djsheep]

Have you tried pushing down on chips and the customs whilst the sprites are missing?

 

[Kundi]

Yep. Also tried to slightly bend the board as this sometimes can help finding bad solder joints... Makes absolutely no difference :/

 

[djsheep]

Are the missing sprites consistent? And does the error only show up during those particular parts of the game?

Have you dumped all the EPROMS and compared them in Romident?

 

[Kundi]

I've completed the first level so far and the error is consistent so far.

The roms I've checked (and also re-burned just to be 100% sure):
2F
8E
8G
10E
10G
16K

3L, 7L and 12K are still the original mask roms and un-socketed... They check okay though. Do you think, I should desolder and dump them anyways?

 

[djsheep]

Definitely worth a try if you’re competent with desoldering. The built in ROM check doesn’t check the actual integrity of the data completely.

You might also want to wait for others to chime in who have more experience with this particular hardware/game also.

 

[Kundi]

Thank you first of all

From that pixelated glitch my guess is maybe a defective SRAM.
My hope is that someone knows, which ones are responsible for the affected sprite layer.