Sega Saturn PCB revisions

BH7236AF, mostly on PAL model 2 VA9 and 7, but not exclusively, as I've seen VA9s with CXA1645M as well. It depends on production run.
All PAL units were manufactured in China (by Wong's Kong King) and Indonesia (by "GS", likely a shorthand code). Except for the VA0s, which were made in Taiwan (by "EF").
You can look up who made which units (including year and VA#) here:
http://evilboris.sonic-cult.net/saturn/

Only in the imaginary realm of audiophiles. Your main problem is noise creeping into the a/v cables anyway, especially if you use SCART, so s/pdif is the best choice (bit-perfect digital output, no noise, quality depends entirely on your amplifier).

Didn't knew about the latter, though I've yet to check those schematics because they are hosted on 4shared, which is IMPOSSIBLE to download from.

I've known of a grand total of 1 Saturn that died because of a leaking cap, and that was a Sophia devkit predating commercial units. The only recurring problem I know is that many PAL model 1s use a type of power supply that doesn't work right after extended use (they emit high pitched whines and the Saturn won't run fine, picture is rolling, won't load discs, etc). It is not caused by caps because people already tried recapping them. The only temporary remedy is to install a cooling fan. Some Japanese VA0s also apparently have the same issue, but I don't have any such units due to the high shipping price, it was SaturnHST who reported that issue.

It differs from model to model. NTSC VA0-5 have them all interlinked, so you switch the crystal, switch a jumper, and it's done. PAL VA7 and VA9 have them like that as well. NTSC VA6+ and PAL VA13 use a different PLL, only the video encoder and the VDP2 are interlinked. PAL VA0 and VA3/5 have them separated fully and have some of them on their own extra jumpers, PAL VA1 is the same but the VDP2 and PLL are still interlinked, a snafu in design I guess, so you can't even use the SW4 switch on the back without cutting the trace leading to PLL pin 1.

They are also put under way more strain due to GDROM reading. Saturns use cd drives from the golden age of the CD technology, at the height of the technological advancement, but before cheap chink players flooded the market and DVDs became common. About their only fault is that CDDA playback is not buffered so you poke the console while it plays music and it'll skip. But buffering wasn't a standard in standalone players anyway, it only crept in later on due to PC drives and portable units requiring it.

Those A-B-C letters would be the form factors, not the components themselves. You'd need a professional electric engineer to check what causes the ripples.
Don't know if it's the extra 9v causing the issues - I'd need a late era Hong Kong model to check.

I have no XRGB so I can't comment on those.

Those are indeed the best, for PAL units. Give it an access led mod, and fix it up so it lights the transparent plexiglass above the cd drive. No need to drill holes that way, and it looks awesome.

 

Thanks, I noticed that site linked in one of your earlier posts, really handy resource although it took me a minute to work out the best way to sort the results!

Shouldn't be too much of a problem, since I will be using a homemade SCART cable which has individual shielding for each video/audio signal

I have just uploaded them to my dropbox for you, hopefully you can download them now:-
https://dl.dropboxusercontent.com/u/38801046/DREAMCAST VA0.rar

So its the first 'A' type PSU that was used on VA0 that has problems? Thats interesting as I just came across this Japanese site which describes a lot of Saturn differences:-
http://nannanseisaturn.web.fc2.com/segasaturn/
It shows that the original Japanese Saturn was designed to have a place for a fan just next to the PSU, the 'A' type power supply PCB even has a cut-out at the front to accommodate the fan.

Its a shame they didnt use one standard jumper location :/
I also read that the VA5 "SD" version has VDP2 Pin 79 connected to ground underneath the chip so you have to lift the leg for a 50/60Hz mod? <THIS INFO IS INCORRECT, IGNORE THIS.
(I just always prefer using the original jumper locations if possible)

Interestingly the Japanese site I linked above seems to think the Sanyo drive isnt as well designed as the JVC drive. Translated it says "This is Sanyo pick-up unit. Portion to be sliding is in plastic. Bad feeling."

Hmm, what about swapping the 240V PSU for a 110V PSU, and then using a stepdown - wouldn't that be a possible way to test if its the extra +9V line causing the ripples?

Sounds good, looks like I will be getting a PAL VA5, thanks! Just a few more questions...

If I was looking for an NTSC model, what VA would you suggest?

Do you have any idea why the VA5 "SD" doesnt actually have VA5 printed on the motherboard?

In one of your previous posts you said "VA9 has two PCB revisions, maybe more, but I've only seen two so far." but i'm not exactly clear what that means. Surely if there are two PCB revisions they should be labelled VA9 and VA9.1? After all a different PCB revision usually means a different VA number?

One last question - if I replace the BIOS with a region free version would it be best to use the USA or PAL BIOS? Are there any differences apart from the on screen BIOS revision letter? and are both compatible with 50Hz/60Hz modes?

Thanks again Druid II

 

Thanks for that reupload of the dreamcast schemas.

The A-B-C thing is just the form factor. You can have several different manufacturers beyond that, as well as different voltage support, etc. SaturnHST reported that some of his Japanese VA0 saturns have problems with the power supply. I've yet to come across this problem on PAL VA0 units, and it also doesn't happen on my own hst-3200, so it's likely that only one brand of power supplies fail only.

They indeed wanted the Saturn to have a fan initially, but the connector was removed early on. I don't know what was it that made the fan necessary, and why it was removed, if it was ever used to begin with. Considering that the faulty power supplies started acting up due to age, I doubt the fan was included because of that specific problem.

The pin lifting is never necessary, as long as you know what lines to cut and where. JP1/2 is the main PAL/NTSC jumper, and on some machines it is interlinked to the rest of the system, on some others (PAL units up to VA5) it is not (entirely). If you are modding a VA SD PAL unit, you just have to put a single switch to open/close the middle two pins of SW4 next to the battery. If you use a small one, you can get it done compact enough so the video cd card still fits. I've been fitting systems with a small switch there for a year now, even other revisions. It's very nice.

They are just referring to the fact that it is more difficult to disassemble.

That would prevent the ripples because you are using a 110v PSU, not because it doesn't have a 9v line. I recall I tried that already, anyway.

Any of them... I have a VA0, VA5, VA7 and VA9 NTSC model, they all work equally fine. If there is a difference, it is so little that I cannot perceive them. Some guides say model 2s are slightly weaker but such statements are easily skewed by ridiculous amount of factors (aged caps, different board revisions, etc.).

They seemed to have stopped using the numbers temporarily between VA1-3 (and VA4-5 are carbon copies of 2-3). VA1 is mentioned in the controller boards though.

The PCBs have changed from 171-7291B to 171-7291C in the first one or two months of production. Small revisions like that are common. They remain listed as VA9 on the boards, with the actual product number missing (I imagine the service manuals should have them listed).

Someone with coding knowledge would need to look into that. 50/60hz should work regardless of BIOS.

 

Thanks Druid II, after searching on ebay I have managed to find a Model 2 VA5 Saturn (Serial starting 'AD65') and its on it way to me now

Having asked a number of sellers for the first part of the serial number to identify the revision, I found it interesting that five Saturns from different sellers that were listed as faulty (Problems reading disks) All had serial numbers starting 'AD69' so were VA9 models made in Indonesia. Probably just coincidence, but I thought it was interesting.

Just to go back to your point here:-

Would the below list be correct for PAL models?

-PAL SATURN MOTHERBOARDS-
VA0 - All three pins separated
VA1 - VDP2 pin 79 and PLL pin 1 interlinked (Fix to enable use of 'SW4' can be seen here)
VA3 - All three pins separated
VA5 - All three pins separated
VA7 - All three pins interlinked
VA9 - All three pins interlinked
VA13 - VDP2 pin 79 and Video Encoder pin 7 interlinked

Just to confirm, to perform a 50Hz/60Hz mod on a revision that has some/all of the pins interlinked (VA1, VA7, VA9, VA13) it would be necessary to cut traces, so that only VDP2 Pin 79 is switched by the jumpers (Or alternatively lift VDP2 Pin 79, which is quite risky) Unless you also swap the X1 crystal to completely change the systems between 'proper' NTSC/PAL, rather than just 50Hz/60Hz.

Also, do only VA0-VA5 have pads present for SW4 on the PCB? and do you know of a specific switch/part number which would fit on the existing pads without modification/using wires?

Lastly, I noticed this picture which shows that the last pin of SW4 also connects to Pin 7 of the video encoder, is that correct? and if so is Pin 7 already grounded elsewhere?

This is from the French guide here:-
http://www.segakore.fr/articles/switch_sat_p2.html

The PSU changes remind me alot of the original Xbox, it would be great to someday get a visual guide to all the Saturn PSU types/manufacturers for reference.

Hmm, what about using a small piece of plastic to insulate the +9V pin/contact on a 240V PSU to see if the ripples disappear?

One final question, I noticed on the released VA13 schematics that on the "Diagrama de Blocos" pdf the NTSC crystal frequency is labelled as '14.318 MHz', which makes sense as that is a multiple of 3.579545 MHz needed for NTSC. However on the "Conjunto PCI VA 13_06" pdf the X1 crystal is '14.302446 MHz' which is quite different. Which crystal frequency is correct for an NTSC Saturn? and what frequency did they use for PAL Saturns? (I'm going to try my luck with a 50Hz/60Hz switched PAL model first, but if I experience video stutter using an XRGB it would be good to know the parts required to convert it to proper NTSC)

Thanks again Druid II, I feel a lot more informed about Saturns now thanks to you

 

They were very common, so you get more faulty units even if the margin of error is the same as with other models. You might be able to fix them by adjusting the laser though.

As far as I know those are the major revisions, yes.

Yeah, you have to cut one or two traces depending on model.

Remember that you also have to set the PLL and the video encoder to accommodate the different crystal. They can be set to switch between pal or ntsc too. But for NTSC units, you can swap the crystal, the jumper, and have a fully armed PAL system.

Yes

No idea for specific switches, but anything that physically fits there should work. The easiest to add there are slide switches with pin contacts (instead of the cable holder ends).

It's different per board.

Working on it on my free time.

Haven't tried that, but I doubt that the fault is in the 9v entering the circuit board, more likely that the other PSU components create some interference. The +9v signal is completely unused everywhere but on the a/v out.

Those schemas are for the tectoy Saturns, which used PAL-M, not NTSC.

 

Is pot tweaking fairly successful on Saturn's with problems reading disks? I have had some success with Dreamcasts, but recently attempted to pot tweak a few Wii's and was completely unsuccessful and in the end I just replaced the lasers :/ If any of the faulty Saturns had been 'AD65' VA5 models I probably would have bought one though.

Sorry, I should have been clearer - I meant on the PAL VA7/VA9 models (and PAL VA1/VA13 with one additional link) you should be able to switch to 'proper' NTSC fairly easily since most/all three pins are already interlinked, so you just need to additionally swap the crystal (Whereas on the VA0/VA3/VA5 models you would have to switch all three pins seperately and the crystal)

Ok, I just thought that the PCB designers most likely had a specific switch model in mind, so it would have been nice to use the exact type intended if possible.

Great!

Well I just thought it was interesting that the ripples are apparently only visible when connected to certain TV's - makes me think certain TV's may be somehow 'causing' interference/power drain on the +9V line straight to the Saturn's PSU, which might cause the PSU to struggle when more power is required to read a disk...just a random thought I had.

Doh! I already knew the schematics were from TecToy in Brazil, so should have remembered that they use PAL-M.

I read your post that said VA2/VA3 are identical to VA4/VA5 - does that mean that the VA4/VA5 revisions were only produced to accomodate the Model 2 design?

Also, just for reference do you know which motherboard revisions used 20pin drives, and which used 21pin drives? All the sites I have found just say Model 1 = 20pin, Model 2 = 21pin, but thats not really specific enough for me.

Oh and I came across your posts here and here regarding two different official Sega Saturn SCART cables, and I also believe the SCART cable with a standard SCART plug (No screw) thick cable and two ferrite cores is an official cable, despite there being no logo/model number on the plug. Whilst searching ebay I noticed a number of Saturns came bundled with this type of SCART cable, far too many for it to be an aftermarket cable. In addition one auction for a brand new/unused Saturn had this picture:-

If you look carefully at the SCART plug you can see that this this Model 2 was packaged with this type of SCART cable. I cant seem to find a Sega model number for the Saturn SCART cable though, does it have one?

Thanks again!

 

That and making sure the tray is not too low/high are the most common steps of repairing disc read errors. It's not as if you've got to lose anything if the machine already can't read discs.

That is the most logical theory, though I've seen a lot of model 2s listed as VA2/3 with VA4/5 insides - although the difference is literally 2 or 3 resistors, a led, and a button removed.

Probably listed in service manuals only.

 

Thanks. Just for reference do you know which motherboard revisions used 20pin drives, and which used 21pin drives? All the sites I have found just say Model 1 = 20pin, Model 2 = 21pin, but thats not really specific enough for me (Does VA2/3 use 20pin, and VA4/5+ use 21pin FFC connectors?)

Thanks again for putting up with all my questions Druid II

 

VA0-1 uses 20pin, everything else is 21pin.

 

Love going away on vacation and coming back to detailed replies to a thread I started, great read!

Personally, though I own a few, if I were to just buy one and only one Saturn it would be the original VA0. It has (what looks to be) the easiest BIOS chip to solder and replace with a region-free BIOS, as well as the newer mod chips allow the model 1 saturns to be modded without any soldering. They are easier now than the model 2's.

 

Every Saturn is equally easy to mod as long as you know what you are doing. As far as the BIOS chips go, I'd say I have an easier time desoldering SMD than DIP chips, but it all depends on your tools.

 

Here vignettes expand without problems?
may be necessary it is registered?
anyway you ca will give access to the download area


and I remember that my method is not academic is an extension to learn very quickly how and what modchip switch frequency can be installed

ici les vignettes s'agrandissent sans problémes ?
peut etre faut il est inscrit ?
en tout cas ca te donneras accés a la zone de telechargement


et je rappelle que ma methode qui n'est pas academique est une vulgarisation permettant de savoir tres vite quel modchip et quel switch frequence on peut installer