Help with a saturn not displaying video or sound

[Jrussell]

Hey there folks, I managed to pick up a model 2 US Saturn recently and I'm having some issues getting it to work properly.

Day 1 it would take quite a while to display the bios after powering on and would then eventually freeze and go back to no signal after a few minutes.

I recapped the PSU board and since then all I've gotten is no signal. Disc tray doesn't attempt to spin and there is no sound. Voltages coming off the PSU seem correct with 5.2v, 5.2v, ground, ground so I don't think there was actually any issues there. Nothing obviously bad to my inexperienced eye on the main board.

Any advice or theories?

 

[black_kawa]

It need too the 12 volts rail to be working to the system boots correctly. If you can check, check for ripple in the power rails, since ripple can affect seriously the video signal. I recently revived a psu from a Model 2 JP, and using a external power supply, the video signal was very unrealiable.

Alternatively, check the reset signals on the SH2-1 to see if the system is really booting, or have a signal frozen

 

[Jrussell]

My understanding was not every model required 12v. As it stands I can occasionally make it to the BIOS screen if I power cycle it a few times, but it runs for about 5 minutes before freezing and then kicking back to no signal

 

[Tiviat]

Always check your capacitors on old hardware PCB. They can DEFINITELY give you the runaround

 

[Jrussell]

Always check your capacitors on old hardware PCB. They can DEFINITELY give you the runaround

Yeah seems that way. I replaced the caps on the main pcb and now it runs for a few minutes then the controls become unresponsive, then it freezes, and then it goes to no signal. I'll give the board another look to see if I didn't miss anything or have a bad solder somewhere

 

[black_kawa]

My understanding was not every model required 12v. As it stands I can occasionally make it to the BIOS screen if I power cycle it a few times, but it runs for about 5 minutes before freezing and then kicking back to no signal

It looks like mine was without the 12v rail functioning. Check your 12v rail and if it reaches the cd block, since the system needs 12v for the cd blocks, that is what causes the freezing

 

[Tiviat]

Yeah seems that way. I replaced the caps on the main pcb and now it runs for a few minutes then the controls become unresponsive, then it freezes, and then it goes to no signal. I'll give the board another look to see if I didn't miss anything or have a bad solder somewhere

I may have to do the very same on my old M1 and M2 Saturns, my other older consoles. Plus, caps are also on the PSU, and dust gets into ridiculous places and wreaks havok on electronic equipment. A good Isopropyl wipe down probably won't hurt. Could you mess with the boot chip or any other of the special chips on their besides the SH2's ? I probably wouldn't hurt to replace any of them(If you can ), and see if those a problem or not.