VA0.5 Not booting.

[deezdrama]

Bought this mint va0.5 Japanese Saturn in the box for cheap but labeled as junk from Japanese mercari.

I've been restoring and modding consoles for a while but never owned or worked on a Saturn before this.

After date/time screen it would just hang on a black screen. No Saturn boot animation or anything. No sound.
I figured it was the optical drive or a bad cap.

Did a complete cap replacement ...
youtu.be/1b6B_QEgM-E

Also installed FRAM.

After replacing all the electrolytic surface caps , power supply through hole caps, and swapping in a FRAM.... I installed the Fenrir ODE.

Used Rufus to format to FAT32
Put newest Fenrir firmware on root of the card.
Dropped a couple games on the card.

I used the original 20pin ribbon cable as it seemed much sturdier.


Powered the system on and I get the exact same behavior.....

Date/time screen then when I enter the date and time and continue it just hangs on a black screen.

No Saturn boot logo, no CD menu, no sounds in date/time screen or after.

Fenrir has blue led on so its getting power


Went through and rechecked all my caps even though I'm compulsive about these things and triple checked everything when I did the recap.
All was good.

I decided to painstakenly reflow every single IC component on the board and daughter board.
Went over entire board with a jewelers loop checking my work,caps,IC legs, nearby traces.

Tried using different ribbon cable on the Fenrir. Tried with battery and without. Tried with the optical drive and the Fenrir.

I have so much time invested I'd hate to give up and throw this thing in the scrapbin.

Any other ideas or suggestions?

Thanks!

[zyrobs]

Well you bought it junked, can't expect to repair everything.

I'd attempt to check the board for broken traces, then test all the logic components (the numerous 74 ICs) which would be easy to replace if they are bad. Then the memory, which is still replaceable... if it's none of those, it is an ASIC issue and in that case you need another dead unit as a donor.
But, if you get as much as the date screen, then the CPU and graphics chips should be working right, and likely the sound too (if you get the jingles when setting the dates).

edit: What happens if you remove the SH1 sub-board and boot it like that? On a va0.5 you should have the 1.01 bios, so it should at least get into the CD player menu, with highly distorted sound (with the 1.00 bios, it just black screens if there's no SH1 sub-board or no cd drive connected).

[deezdrama]

Oct 10, 2021 8:21:31 GMT zyrobs said:

Well you bought it junked, can't expect to repair everything.

I'd attempt to check the board for broken traces, then test all the logic components (the numerous 74 ICs) which would be easy to replace if they are bad. Then the memory, which is still replaceable... if it's none of those, it is an ASIC issue and in that case you need another dead unit as a donor.
But, if you get as much as the date screen, then the CPU and graphics chips should be working right, and likely the sound too (if you get the jingles when setting the dates).

edit: What happens if you remove the SH1 sub-board and boot it like that? On a va0.5 you should have the 1.01 bios, so it should at least get into the CD player menu, with highly distorted sound (with the 1.00 bios, it just black screens if there's no SH1 sub-board or no cd drive connected).

Sofar in my retro modding journey I've just replaced capacitors, done a few nes rgb mods, things like that... I know how to check voltage,capacitance, and continuity but never had to troubleshoot anything like this.
How would I even go about testing all the logic components?
Ive been wondering what that sub board was called lol. So if I remove it and it behaves the same, could that indicate that the sub board could be the possible issue?

Know of any videos or guides that might help me with testing and troubleshooting?

Thanks a million!

[zyrobs]

So if I remove it and it behaves the same, could that indicate that the sub board could be the possible issue?

If you remove it and it behaves different, then it is possible that something on the SH1 side does not work. Of course it's also possible that something that tries to communicate with the SH1 is having a fault. But on VA0.5 motherboards, the SH1 sub-board is removable, so it would take no time at all to check that.

Many IC programmers have the ability to test logic chips. RAM testing is a bit trickier, but there are tools for that too. You also need adapters since most things on the Saturn are SOP, while testers are for DIP packages.
The thing is that unless you regularly repair stuff, a tester is not worth the cost because it is simpler to just buy replacement 74xx components, or even a new Saturn altogether.

Problem is that if your Saturn can show up the date selection without glitches (and playing sound), then the majority of the system is already working fine - the two video chips, all the VDP1 memory, the boot rom, at least one of the VDP2 memory banks, the master SH2 and the work ram high must definitely be working. Work ram low is not used on the bootup process, and I think the slave sh2 is unused too. If you get proper sound on the date selection, then the entire sound subsystem is also working correctly. SCU must be working since it handles nearly all data transfers, but the DSP inside is a toss-up (it is used during the animation but only for something trivial). The clock signals generated by the PLL must all be good too, otherwise most of the system just would not work.

That leaves the SH1 sub board, the SRAM chip, the DCC which communicates with the SRAM, and the RTC clock part of the SMPC.

[zyrobs]

Wait, I just noticed that part where you say you have NO SOUND. Does that mean there's not even any jingles when you set the date? That would mean that something on the sound side is broken.

First up I'd check if the clock signals connect right. There should be service manuals available online for the PAL VA0 unit which is largely the same other than some jumpers, you can use that as a reference for which pins to check. If your multimeter can check frequencies, you should also be able to measure the signal, it's not as informative as using a scope but you'll at least be able to check if there's a proper clock in there or not.

If you are lucky, it's just a broken trace connecting the 68k, SCSP, and sound memory together and with the rest of the system - the trace may be under those ICs, so you could consider desoldering them and inspecting the board.
Or the sound memory is broken. I'd try switching it out with one of the work ram low chips, I think they are the same type, 512k and same j-wing packaging. That should at least confirm if the issue is that, the console can boot without the work ram low but it won't get too far in games.

I think, in that case, the SH1 sub-board should not be a culprit. But if memory serves, the sound clock is derived from the clock the system receives from the CD drive, so removing it may shake things up enough for the system to behave differently.

Also, try holding the blue button next to the battery. That will reset the memory and date completely. It might help if something was dodgy there, but I think the issue is with the sound subsystem side of things.

[deezdrama]

I really appreciate the detailed comments.

Yup no sounds at all in the date and time screen. This will give me somewhere to start.

I swapped SRAM for FRAM.
I'm confident it wasn't my work that caused the issue as it was doing the same thing when I received it. Was hoping a recap would solve it.

What would cause a trace to get damaged if the system was never opened before? It didn't appear to be anyway.
I'll have to find a component map of the board and start checking traces between components you mentioned.

Recapping, some surface mount stuff here and there, swapping a couple IC chips is stuff I'm confident with..... This sounds like it may be beyond my capability to repair but would be nice if I found something simple or obvious...you never know lol

[davyk]

You seem to be enjoying yourself. Learning about the hardware. Won't be effort wasted even if it doesn't work in the end.

[zyrobs]

Oct 11, 2021 4:17:54 GMT deezdrama said:

What would cause a trace to get damaged if the system was never opened before? It didn't appear to be anyway.
I'll have to find a component map of the board and start checking traces between components you mentioned.

Recapping, some surface mount stuff here and there, swapping a couple IC chips is stuff I'm confident with..... This sounds like it may be beyond my capability to repair but would be nice if I found something simple or obvious...you never know lol

The pcb can just break down over time due to contact with air, depending on air quality and potential flaws. A while ago a guy had a broken trace that caused video glitches, and the broken trace happened to be under one of the qfp chips. So, it can happen.

Checking whether all pins are connected to where they should be is a very good start for troubleshooting. Here's hoping you find the culprit that way.

[deezdrama]

Oct 11, 2021 10:55:03 GMT davyk said:

You seem to be enjoying yourself. Learning about the hardware. Won't be effort wasted even if it doesn't work in the end.

Its frustrating but at least I'm learning as I go

[deezdrama]

I've found leads from a member on another forum that had similar issues and he suggests my issues could be from bad ic31 or ic32 ram.
Sadly I never learned to read these schematics and have no clue really how to do further testing.
I removed the boards again and checked all my capacitor, FRAM work. Everything looks fine.
Checked all pins...good. All traces look good. No oxidation or degradation anywhere.The board and system looks pristine.
I can replace these ic components no problem but scared to buy another Saturn after this.
This is the first console I couldn't get working again. I found another va0.5 for parts dirt cheap but has exact same symptoms so I would just be blindly swapping components that could have the same issues.
Guess it's time to hang the towel up and sell my Fenrir and psk cart 😔

[zyrobs]

I doubt it's the low ram giving you the problems, since you don't get any sound whatsoever. But for a test you could just remove both of those ram chips and exchange them.

You can check the schematics to see which pin connects to where. Then use your multimeter in continuity mode to test if they actually make a connection. It is possible there's a broken trace UNDER one of the chips that you don't see.
That and a broken sound clock are my best guesses - check IC24 pin 2 (or TP21) which should read 22.58 MHz (this is the SCSP clock), and IC24 pin 10 or TP22, which should read half of that (this is the 68000 sound cpu clock). If your multimeter can measure DC frequency, that should be enough for checking the clocks, assuming it can read as high as these values.

[deezdrama]

Oct 14, 2021 14:36:08 GMT zyrobs said:

I doubt it's the low ram giving you the problems, since you don't get any sound whatsoever. But for a test you could just remove both of those ram chips and exchange them.

You can check the schematics to see which pin connects to where. Then use your multimeter in continuity mode to test if they actually make a connection. It is possible there's a broken trace UNDER one of the chips that you don't see.
That and a broken sound clock are my best guesses - check IC24 pin 2 (or TP21) which should read 22.58 MHz (this is the SCSP clock), and IC24 pin 10 or TP22, which should read half of that (this is the 68000 sound cpu clock). If your multimeter can measure DC frequency, that should be enough for checking the clocks, assuming it can read as high as these values.

My multimeter only tests frequency up to 2MHz 🙄
I would of bought a better one if I knew I'd ever need a high freq function

[pastperfectgames]

Please take a look at my recent post - I had very similar symptoms that I was able to fix: segasaturngroup.proboards.com/thread/11965/repairing-strange-black-screen-issue