2nd DC having a fried motor driving chip...

[Tiido Priimägi]

sometime ago, my DC's drive's motor control chip died... no reason for it to do so IMO... So I utilized my spare drive there...

And now, some hours ago, I was playing SA2 on my DC, and I heard a nice crack, smelled the magic smell and my DC quit spinning the disc... as before, problem in the motors control chip having a hole in it...

Is this a common problem amongst DCs ?

I've got 3 drives already, all with a hole in the motor control chips... I only have one spare drive left to use...

All PSU voltages are within ranges... I cannot think of anything that might case the "early" demise of that chip....


PS, I'm having a Saturn drive with a dead motor control chip aswell... Saturn drive board has much bigger chip though, not a small surface mount chip...

[l_oliveira]

one of the motors have it's brushes shorted.
Doesn't mater how many boards you exchange, you will fry each one you try on that mechanism.
To don't damage another BA chip, test both motors with a multimeter for impedance (should be arround 8 ohm for the small motor and 13 ohm for the big motor) while spins them. If they're shorted they will measure 0 ohm at a certain position of it's axis.
Also I'd suggest you to open the faulty motor just to take a look on how damaged it is.

[Tiido Priimägi]

I'll see about this then... Good I'm using another assebmly then if dead motor is the case

[ken_cinder]

I have a spare Saturn drive boxed up here, and a power supply. Both came out of a PAL unit.
I'd sell em to you on the cheap, they're just taking up space.

[Tiido Priimägi]

When I have one thing bought and still have some spare money left, I'll see about the PSU and drive... Actually one Saturn PSU just died all of a sudden a while ago, so a spare one can come in handy


As for the motors, maybe my testing method was not perfect, but I could not get any lower than usual ohm count from any motor...
both chips have a hole in same place so I'll see which motor is closest to them I'm having 3 spare assemblies anyway so breaking one in the name of science will be good

EDIT: Both motors were fine...

[l_oliveira]

After opening the motors, inspect the brushes and the rotor for "grooves" if the rotor has grooves, it's damaged.
If you were gentle while opening the motor it should be possible to close it again with solder.

And the motors being shorted is the only reason I know for the BA chip blow is short circuit on the motors.

To properly test them, attach wires to them and link them to the ohm meter probes or use probes with alligator clamps.
Spin the motor gently and see is at any point it's impedance drops.


The Dreamcast is so bad about wear out of the motors for two reasons:

The big motor: The Dreamcast works using CAV (Constant Angular Velocity) to enhance the throughput of the drive so it means the big motor spins all the time at the maximum speed, meaning that it draws a lot of current when it's starting the disc. Because of that, the BA chip has to be able to feed the motor enough current to allow it to accelerate. That means if the motor is shorted, there's enough current to cause the BA chip to blow it in less than five seconds.

The small motor: It moves the laser pickup through the disc and because the Dreamcast employs audio streaming on most of it games (Through SEGA/CRI ADX format) it will move the optical pickup a LOT while trying to read both graphics and music from the disc. Another aggravating factor is the use of pirated discs, as these have a lower data density (they're CD-ROM after all) meaning the drive will have to move the pickup more to load the data ...  All that plus the fact that Yamaha engineers (yes, the drive was developed and manufactured by Yamaha for SEGA) choose to use brush motors on their console while all other optical storage products were actually avoiding them (the PS2 uses stepper motors on it's drive, sadly DVD lasers are quite temperamental lol)

It's possible to obtain the same BA chip from old DVD or DVD drives or Recorders.

[Tiido Priimägi]

There were visible grooves on the area which brushes touch...

I got motors open and closed without problems... though I'm actually not too sure about the big one, I'm quite sure that its brushes are somewhat damaged when I closed the motor... battery made the motor spin though... anyway, I'm not going to make use of that assembly... I'll borrow its laser mechanism when I get a drive with dead laser.

Yamaha did everything for Sega, even the VDP in MD is actually made by Yamaha.