Mario Bros. No characters on screen?!???? Please help!

[sk8ersublime]

I'll toss a socket in for you with the chip order.

Cool. Thanks! I am hoping it's just cold solder since the member I bought it from says it worked when it left his place. He offered a refund but I need everything that came with it as well (harness, cage, filterboard, power supply) so hopefully it's a simple fix.

If re-soldering does not fix the issue I'll replace the DMA. I haven't tested yet because I do not have the cab or board with me. And I wanted to have the part before I went back up.

Thanks again! I'll post my results.

 

[sk8ersublime]

This fucking board. I replaced the DMA and now I am only getting garbage on the screen. It's the same image with the DMA chip completely removed. I'm guessing something is fucked there.

I guess I'll be looking for a new boardset or I'll be getting a 19-1 or mame. WTF!!? It's so frustrating.

 

[sk8ersublime]

Grrrr.......

 

[That80sGuy]

ok.. take a deep breath. Maybe its something else. Have you re-seated all the socketed chips..making sure they are firmly in place?

 

[channelmanic]

Did you pull a trace or create a nice solder short?

Look at the pins on the chip you pulled for nice copper colored junk on the pins. If you see that then you pulled out some or all of the plated thru holes.

 

[sk8ersublime]

Nope everything looks fine, I even tested all the points with my meter on "ring" mode. Making sure no traces were broken and that nothing was bridged. I tried with the socket then I removed the socket and put the chip in directly, no dice.

 

[sk8ersublime]

I fixed it!! I went back to everything, reflowed and it's working!!!!!

There is a small artifact under the B on the title screen, but everything else looks fine.

 

[sk8ersublime]

What would fix the B artifact? There was a piece of solder bridged on another chip before I ever started. I removes it because it was bridging to legs of a chip together.

 

[channelmanic]

Probably a bad memory chip. I wouldn't worry with it until it gets worse.

 

[sk8ersublime]

Probably a bad memory chip. I wouldn't worry with it until it gets worse.

Ok cool! Thank you so much for all of your help!

 

[BladeZX]

Sorry to bring this thread back but I have the exact same issue with my Mario Bros
I replaced the Z80A DMA but all moving sprites are still missing - I even tried 2 z80a dma chips
What else could be causing this?
Thanks

 

[HudsonArcade]

DMA chip is just the easy low-hanging fruit that doesn't require any actual debugging.

All it does is copy data from the main RAMs to the 2148s on the video board, which is where the complex stuff happens.

Start with the 4U/5T mux selects and work back.