Saturn CD drive problem

[Tiido Priimägi]

So after about 36 hours of use (memory full, no RAM cart, too good game to stop playing) my Saturn started seeking all over the CD and crashed... so I did a reset and it reports drive empty... and comes out that CD won't spin anymore, laser mechanism is fully working...
My initial thought was dead motor control chip, but after some making bakery out of excremental matter, it seems its not the case...

I had another CD drive with exact same problem, so I desoldered the BA chip (it had no visible signs of damage) and I partially piggy backed it on the existing chip on one board I was trying to rescue. The chip has 4 sections so I used one that was used to adjsut laser lens because that worked fine... and the motor is still not spinning (I did disconnect outputs of the existing chip before making use of new one...).

Also, I can rule out the motor being dead, there's nothing wrong with the motor, I even hooked up another motor, and it won't work either.

I must say that the CD did spin up for a moment before doing the piggybacking stuff, but it was momentairly and only after power off/on cycle...

So, does anyone have any clue about what else might be wrong ? Only chip that is connected to the driver chip is a small rectangular probably half digital chip, which is possibly some custom one (cannot see what's written on it)...

If all fails, I'll have to look into getting a 20pin drive somewhere

[l_oliveira]

If it has a modchip, I'd say it's the mod. The first thing one must do is aways try the system without the modchip.
It's the first thing to fry.

Also, the 20 pin model has the CD-ROM main processor (an SH-1) on the small card with the MPEG card connector, together with the CD-ROM bus interface chip. Sometimes that connector fails... Re-seat it might solve the problem.

[Tiido Priimägi]

it is most definitely not mod chip problem as I have none, and I have done the re-seat process some 20+ times when I was juggling around with the drive trying to get it working....

I attached some extremely poor pics of the board...

[l_oliveira]

Trying my best to help you let me list what each part does:

HD6433713H     H8 Microcontroller: Controls the mechanism/CD reading. (Hitachi - CDM102V seems to be the firmware revision programed in it's mask rom)
HD49236FS       CD ROM DSP for disc reading and error correction  (Hitachi)
LH5116NA-10   2KB SRAM dor the DSP (Sharp)
HA12178          CD optical pickup Front end processor: detects the data from the photo diodes (Hitachi)
BA6385FS        LASER LED gain control circuit  (Rohm)
BA6798S          Motors and focus/tracking coils driver.

Several years ago I repaired a Saturn drive by replacing the BA6385FS. But then it were skipping badly but would still detect that there were
something on the drive. Just could not read the disc properly. In the end the laser was being powered with a voltage lower than the optimal.
I took the spare part from a drive board that was broken (the owner was pissed that he lost in a game and smashed the top of the saturn)

[Tiido Priimägi]

comes out that the motor driver chip is not dead at all... only potential trouble maker is the small QFP (HA12178 ?) on top of the scan... or something around it... the driver chip does not get a signal from it, at least it seems so...
Anyway, I'm getting a new Saturn shortly so this is not too important anymore..