Wonder Boy sprites issue

[MRCMRC]

Hi.

I've a Wonder Boy PCB. Game plays really fine, background graphics are good, but sprites are bad. They look in good shape, but covered with horizontal lines.

The sprites were OK the first time I powered up the board, but turned bad a couple of minutes later, and now they are always bad.

Could you please give me any hints of how to solve this issue? Sprites ROM are good. Maybe is a RAM problem?

Thanks!!!

 

[MRCMRC]

If it helps:

Some items and enemies sometimes show good, sometimes bad. And the colors of the lines that cover the sprites change also during the game.

I also would appreciate very much if anyone could tell me where I can get the Wonder Boy PCB schematics.

Thanks!

 

[FullThrottle]

Have you checked your power supply voltages and power at the board? You may want to adjust this, some pcbs are finnicky about the correct voltage. Also, you may want to carefully remove each socketed chip one at a time, make sure the legs are nice and clean, non-bent, and very carefully re-socket them, making sure they're nice and firm, and that all the legs are in the correct slots!

 

[FullThrottle]

http://www.crazykong.com/manuals/WonderBoy.man.pdf
Theres a link to the factory manual, but I couldn't find a pcb schematic.

 

[arcadecup]

is this the common bootleg wonderboy board?.. ive seen this also on that board and have changed on of the character eproms and it cleaned it right up.. i dont recall which one.

 

[MRCMRC]

Thank you very much for the help.

I've reseated socketed chips and adjusted the voltage to 5.00 V measured on the board, and still the problem.

It is an original PCB, and I've tested all the ROMS and they are OK (I have Wonder Boy (System 2) as appear in MAME).

I'll try to describe a little bit more the problem. Sprites and items show in god shape. But the alternating lines showing in the monitor are one good color, one bad, one good color, one bad, and so on. The bad colored lines doesn't have always the same color. And, for instance, the clouds sometimes show all good, sometimes bad. The same occurs with fruits, and some enemies.

Thanks again for the help.

 

[FullThrottle]

I'd recommend sending it to a pcb repair specialist... I know it costs money, but if you want to ever quit smashing your head on the wall, its a good solution!

 

[MRCMRC]

I've also noticed that the horizontal lines that are showing bad, had also good shape, but bad colors. That is, even lines shows good (shape and colors) and odd ones show bad (good shape, bad colors). It would point to a bad sprites RAM, or to a bat palette RAM, but I've noticed that sometimes the bad shown lines change: even lines are now showing bad, and odd ones are good!

I've read that some games have a different RAM for odd and for even lines in sprites. Maybe this is the case. But if one of these chips were faulty, the bad lines of the sprites would be always the same... So weird...

If I only had the PCB schematics of this board, I could trace the problem much more easily, before starting smashing my head on the wall as FullThrottle says.