Black screen and drive problems with NTSC-J Model 2 Saturn

Eidolon_NG

Eidolon_NG

Hi again,

my next problem relates to a newly-bought "Skeleton Saturn" ("This is cool!" model).
I hope - with the community's help - I'll be able to revive it.

Hardware info:
- Model HST-3220
- Mainboard: Seems to be a VA15? (PCB info: Sega 171-7462B PC BD Saturn VA15, Made in Japan, 837-13137 IC BD Saturn Main VA15 JPN, (c) Sega 1997)
- CD Drive: Assy CD Unit Sat Jvc EXL-P608, Made in Japan

The symptoms are:
- it only shows a black screen when powered up
- the CD drive does not spin up the disc. The laser unit however moves (e.g. if pushed to the outside, during power-on it moves to the center) and tries to focus the laser on the disc (move up/down of the lens visible)

What I already did is:
- switch the CR2032 battery to a new one
- clean the flat cable between CD drive and mainboard on both ends with Isopropyl alcohol
- measure the voltage coming out of the power supply board on Pins 3 and 4 when Saturn is powered on. Both are fine (?) with 5,05V.

My questions:
- What can I test to evaluate further and pin-point the problem?
My lab-at-home is equipped with soldering station, multimeter, logic tester, so I can use all of these to hunt down the error in either device (3D controller or Saturn)

Thanks in advance - any help appreciated!
 
It could be that the motor controlling the spindle is "toast" it happened to me before on one of my previous saturns from doing the swap trick too much (before pseudosaturn was out and long before I installed a modchip in my current one). I'm heading off to work right now, but I'll see if I can get your started on some troubleshooting when I get back later on tonight.
 
Thanks, that would be appreciated. Unfortunately, it seems to be that only very few and bad quality hardware docs of the Saturn have surfaced. It would be worthwhile to start a wiki for troubleshooting topics such as this (or my controller problem, see other thread).
 
Eidolon_NG said:
Thanks, that would be appreciated. Unfortunately, it seems to be that only very few and bad quality hardware docs of the Saturn have surfaced. It would be worthwhile to start a wiki for troubleshooting topics such as this (or my controller problem, see other thread).
Click to expand...

Disclaimer: I'm not responsible for any damage to your console or any harm to yourself as a result of following any of these instructions, use extreme caution, especially if you have the case off while doing this. You seem like a pretty smart guy, but just covering all my bases legally 😛. This goes for anyone else following my instructions as well.

Amen to that! With so many different models and different drives/laser assemblies etc this would be very beneficial. Before we try and hit anything with a meter, have you tried taping down the switch that tells the drive that its closed so you can watch the laser lens (DON'T STARE DIRECTLY INTO IT, but from an angle) to see if its lighting up initially without a disc in the drive. It should light up while checking to see if there's a disc in the drive, should be pretty quick before it gives up (unless a disc is detected).
 
Yes, the laser lights up. It seems to be a little less shiny red than the one in my PAL Model 1 Saturn device, but it's there.

The Saturn only produces a black screen though, no startup sound is audible.
 
Eidolon_NG said:
Yes, the laser lights up. It seems to be a little less shiny red than the one in my PAL Model 1 Saturn device, but it's there.

The Saturn only produces a black screen though, no startup sound is audible.
Click to expand...

Oh I'm sorry I misread your original post. Didn't realize it was black screening. Have you tried simply just wiggling the av connection around on the console end/unplugging and replugging? Also is there a modchip installed in this console? That could potentially be causing an issue if the chip is bad or a connection isn't right...
 
It is an unmodified console.
I rule out a RGB Scart cable connection problem; the Saturn seems to be quite new, and the same RGB Scart cable works perfectly with my Model 1 PAL Saturn.

Or is an RGB Scart Cable made for PAL Saturns not compatible with NTSC-J Saturns? To my knowledge, this is compatible; only the other way around (use a cable made for NTSC consoles on PAL machines is not allowed)
 
Check the pinout of what's on the av out jack on the suspect saturn vs. your scart cable. If there's a mismatch this could be your issue. If that's the case I suggest going on ebay or amazon to get the correct cable
 
Further testing... But no solution yet.

Tested: The CD motor spindle works fine (verified this with the little 1,5V battery trick found on youtube, attaching the battery directly to the motor. It spins.).

Other than that, the device is still dead. I opened it up, and checked the supply voltage for the only IC I could identify - the ROM chip "MPR-...". It's got 5 Volts, as do the controller ports.

The only thing I notice is that the SH2 chip (the one combining both SH2 logic in one chip, labeled 315-6018) and the chip labeled Sega 315-5883 become rather hot, while the other ICs stay rather cool.

Also, the optical check of the board (both above and below) is fine, I see no traces of any caps leakage or something.

I wish we found a Sega Saturn VA15 board service manual...
 
I wonder if those IC's you mention that were getting hot are toast. At data sheet on those IC's would be helpful for figuring that out as you could take a meter to each pin (with the ground against the case) to see if its outputting the right voltages etc....
 
I got hold of the Saturn VA13 Board Service Manual now. Luckily, there are some similarities between a VA13 Board and my VA15 Board Saturn.

So, I could do some measurements against the specs, without having a clue how to interpret the results now.
Looking forward to ideas/tips on how to proceed!

Measurement power supply onboard circuitry
- CF1 = 5,05V (VCC)
- CF2 = 5,03V (VCC2)
- L8 = 5,03V (AVCC3)
- L9 = 5,03V (AVCC2)
- IC42 Pin 3 = 3,33V (LVCC)
Measurement CD Unit Power supply
- CN7 Pins 1/4 = 5,05V (CD Drive Connector)
Measurement A/V Out Circuit ICs
IC21
- Pin 12 = 4,92V (VCC1)
- Pin 19 = 4,93V (VCC2)
IC22
- not possible to measure for me, because difficult to reach below power supply board
Measurement IC9 (Sega 315-5744)
- Pin 16 = 4,84V (VCC)
- Pin 15 = 4,79V (Reset) !!!!! potential problem?! - stays high
--> maybe IC35 (S-80723AN-DL) defective? Here Pin1 (CS=Reset) stays high
- Pins 13/14 = ~50Hz (X1/X2 32768kHz) --> probably my multimeter can't measure this correctly
- Pins 10/11 = ~50Hz (OSC1/OSC2 4MHz) --> " "
Measurement IC17 (Sega 315-5965)
- Pin 124 = low (Resetn)
- Pin 116 = 5,05V (Vcc)
Measurement IC14 (Sega 315-5964)
- Pin 78 = low (Reset)
- Pin 85 = 4,95V (AVCC)
- Sample VCC: Pins 10/151 = 5,03V (VCC)
Measurement IC5 (Sega 315-5966)
- Pin 100 = high 5,05V (Reset=SYSRES) !!!! potential problem?! stays high - what could be the cause of this?
- Sample VCC: Pins 208 = 5,03V (VCC)
Measurement IC37 (Sega 315-5962)
- Pin 115 = low (Reset=CDRES)
- Sample VCC: Pin 7 = 5,03V (VCC)
 
Last edited:
If possible could you take a picture of your motherboard? Preferably with a high megapixel camera? That way I can try and help you map out what's what.
 
Hi @SegaSaturnShrine , thanks for the offer, but no need for you to spend time on this. I could identify all but two ICs and measure them. The two ICs have to be integrated versions of VDP1+VPD2 (IC10, 315-5883) and the integrated Dual SH2 (IC1, 315-6018).

Even if I do not have the schematics for these, I can conclude with 99% probability that the board is dead, seeing that all measurements are normal, except maybe IC35, which I need to doublecheck).

I now need to buy a working Model 2 Saturn (preferrably VA15, but VA13 would be ok too I guess) as a reference device to compare the dead board measurements with the working one measurements.
 
Eidolon_NG said:
Measurement IC9 (Sega 315-5744)
- Pin 15 = 4,79V (Reset) !!!!! potential problem?! - stays high
- Pins 13/14 = ~50Hz (X1/X2 32768kHz) --> probably my multimeter can't measure this correctly
- Pins 10/11 = ~50Hz (OSC1/OSC2 4MHz) --> " "
Click to expand...
As a rule, reset lines are active low, and the SMPC's reset line is supposed to stay high until the reset button is pressed. Measuring the clocks in the system is a good idea, but you need an oscilloscope for that.
 
antime said:
Measuring the clocks in the system is a good idea, but you need an oscilloscope for that.
Click to expand...

Unfortunately, I only have a multimeter for measuring up to 10MHz pulses and a logic tester to detect pulses in general.
With this, I could verify:
- X3 has a correct frequency of around 4MHz (I measured 3.991MHz with the multimeter)
- X4 has a correct frequency of around 32768 Hz (I measured 32.76 kHz with the multimeter)
- X1 shows a pulse with my logic tester - it is supposed to have 14.3MHz, but I can't measure this with my equipment
- X5 shows a pulse with my logic tester - it is supposed to have 19.978MHz, but I can't measure this with my equipment

---> how likely is it that X1 or X5 have failed and produce a different frequency than specified?
 
@antime is right. I mean for troubleshooting most circuits a multimeter is sufficient but at a high frequency of 10mhz its going to be very difficult to tell what's going on. An oscilloscope would be ideal, but yeah if you don't have one, there's not much else you can do.
 
Eidolon_NG said:
how likely is it that X1 or X5 have failed and produce a different frequency than specified?
Click to expand...
Not that likely. Crystals can suffer from mechanical damage, but a missing or malformed signal can help zero in on the actual problem.
 
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