ST-V Motherboard Issues

[nekojeeta]

Hello,

I'm a novice at fixing boards... I have two ST-V motherboards that won't load games (black screen). One board will let me get into the test screen and seems to get a video signal per my OSSC, but the other board can't get into the test screen and doesn't get any video signal.

I'm wanting to discharge the capacitors as a starting point, but I was a little confused on the best way to do this:
- Do I need to desolder each capacitor and remove it from the board to discharge it?
- To discharge can I just take a screwdriver or pliers and touch both contacts at the same time or do I actually need to figure out the ohms and create a high wattage resistor tool to discharge?

Thanks!

 

[Kundi]

Bridging both legs with a screwdriver is more than enough, no need to desolder.

 

[nekojeeta]

Thanks!

 

[pvwradtke]

Hello,

I'm a novice at fixing boards... I have two ST-V motherboards that won't load games (black screen). One board will let me get into the test screen and seems to get a video signal per my OSSC, but the other board can't get into the test screen and doesn't get any video signal.

I'm wanting to discharge the capacitors as a starting point, but I was a little confused on the best way to do this:
- Do I need to desolder each capacitor and remove it from the board to discharge it?
- To discharge can I just take a screwdriver or pliers and touch both contacts at the same time or do I actually need to figure out the ohms and create a high wattage resistor tool to discharge?

Thanks!

At least one of them could be one the secondary CPUs that has cracked solders - you should be able to play a game that doesn't use the secondary CPU (e.g. Shanghai). Just use good flux and re-solder the CPU and it should work if there's nothing else busted. For the one that boots to a black screen, it could be the same problem - probably the primary CPU that has the bad soldering, but both could have the issue as well. Best just to do the full job on this one and work on both CPUs (the SH processors).

This is, AFAIK, a very common issue with ST-V boards, and just re-soldering the CPU is enough to bring them back to life.

 

[nekojeeta]

Thanks - I finally got one of the boards working (whew!). I'm just going to sell the second ST-V Board + Darksoft Kit + Case as I don't have the time / skill to diagnose and fix.