Saturn VA9 - No picture, no sound

[tmppro]

I've come across this board a couple of times during troubleshooting for other Saturn issues and it has been really helpful, so I though I'd ask for advice for this problem
I recently got a Model 2 Saturn with the dreaded 'no image, no sound' issue. The TV flickers when I turn it on, but that's it.
The drive spins up normally, reads the TOC but not any data. Trying to navigate blind past the language/date screen doesn't change anything either.

Since most issues come frome capacitors I've already replaced all the electrolytic caps on the board. I tested all the old ones as well, all of them were within specs.
I can also rule out the power supply, the voltages are fine (5.01V, 9.28V) and I've swapped in one from a working Saturn, no change.
The AV connector is ok as well.


Here are 2 pictures of the board:




(Ignore the larger 47uF caps on the upper right, I've run out of small ones )

I haven't been able to spot any broken/corroded traces so far. Maybe someone has some ideas on what areas I could check.

[nevermind]

You sure its not a dodgy scart cable? Have you tested it on a working Saturn? Try a RF or composite video connector? If scart cables are not wired correctly you can get the flicker when it turns on.

[tmppro]

Yep, it's not the RGB cable. I'm using the official Sega one, it works fine on my other Saturn and I've also checked the connections from the Pins of the AV Port to the Scart plug with a multimeter.

I'm pretty sure the problem isn't related to any of the video/audio output circuitry because the Saturn doesn't read data from the game discs.
Looking at the block diagram of the service manual, I guess I would rule out the ICs in green:


The drive and expansion stuff on the upper right isn't related to the problem.
With a broken IC17 or IC22 it should still boot and output video. And with a broken RGB encoder (IC21) it should still output sound.

But other than that I have no idea how to narrow down the fault.

[zyrobs]

The "drive spinning up and moving the laser to the inner ring" is handled by the SH1, so if the console does that, then the CD Block part is indeed working fine and can be ruled out (IC37 and 38).

If you already recapped it, then it probably has an IC fault or a bad power supply. And yeah those low profile caps are a pain.

But, the single board model 2 units all have a problem where they need to be left on for a while to start working right, and will crash before that happens. Maybe that affected your unit so much that it doesn't go as far as the boot menu already. Try turning it on without the CD drive attached. If it by some miracle goes into the date select that way, then it's that thing I mentioned, and I've no idea what is causing it - the power supply being the most likely suspect.

Other than that, try heating up some components one by one and see if they boot up that way. I heard a guy who managed to find the problematic IC that way (the fault ended up being the main memory, IC3 and IC4).

Maybe try reworking the solder on the ICs?

[tmppro]

Bit of a late reply, but I didn't have any time to spend on the Saturn during the week.

Those later boards with the through-hole caps are quite easy to recap I think, the earlier ones with SMD capacitors take much more time. I use a desoldering station with a built in vacuum pump, so it's easy going without the chance of damaging any traces.

I've left the console on for about an hour (without the drive connected) and restarted it afterwards a couple of times, but that didn't help. I've checked the temperatures of the ICs with a cheap laser thermometer, but unfortunately there no IC that gets suspiciously hot (about 40°C at most, warm to the touch).
Gently heating the ICs one at a time with my hot air station set to 100°C (lowest setting) didn't trick it to boot either.
I've also spent quite a bit of time checking the solder connections and probing around with a multimeter, but didn't find anything wrong.

I guess it's time to write this one off. It's a shame because the Saturn is in excellent condition otherwise (well, if you can say that with the main component being dead).
Finding a replacement board will be impossible, but maybe I get lucky and find a smashed up japanese Saturn with a compatible board.