I'd agree with SignOfZeta - I'd be surprised if the issue was capacitor related. As far as I know the Sega Saturn isn't known for capacitor issues, so I'd look at other areas. Also, I don't think that having both no audio and no video is a common issue with the Saturn, so hopefully it is an easy fix...
Sounds like you've already checked:
- AV cord
- Power cord
- Power PCB
I'm not sure if they're compatible, but if it's possible swap the laser assembly from a known working unit into this unit. On that note, swap everything you possibly can, one at a time, from a known working Saturn and this Saturn for troubleshooting purposes. Hopefully that will help narrow things down even further.
My general thoughts for this type of issue:
- Examine both the external and internal components visually for ANYTHING that looks suspicious. Check the jacks/ports for debris, bent pins, cracks, old solder, etc.
- AV cord
- AV jack
- Laser lens issue - needs to be calibrated or replaced
- "Lid open" switch - check and make sure it's connected and functioning properly
- Remove any RAM or other carts from the cart slot
- TV jack issue
- Switch selector issue ( if you're using one of those "plug 8 game systems in at the same time" devices)
If you want to replace the caps, send me some macro photos of the caps you want to replace and I'll help you identify the values