Marty's PSU and voltages

[miisalo]

Hello

Friend bought FM Towns Marty and when it arrived, CD didn't work anymore. It basically does not spin it. When I measured voltages, PSU gives out 5V, 8.5V and -8.5V when connected to the system. Are those lines supposed to be 9V or 12V lines? Has anyone the PSU pin out? I would rather replace the PSU with picoPSU etc than repair it, if I would know the pins.

[kamiboy]

Cannot say about the Marty, but the FM Towns II PSU's put out 12V. Though I am not sure whether the negativ line was -5 or -12.

[caius]

Hello

Friend bought FM Towns Marty and when it arrived, CD didn't work anymore. It basically does not spin it. When I measured voltages, PSU gives out 5V, 8.5V and -8.5V when connected to the system. Are those lines supposed to be 9V or 12V lines? Has anyone the PSU pin out? I would rather replace the PSU with picoPSU etc than repair it, if I would know the pins.

Your voltages are good, this is the pinout according to measurements on my Marty II console:

1 +5V
2 +5V
3 +8.38V
4 +8.38V
5 -8.22V
6 GND
7 GND
8 GND

If your CD doesn't spin, most likely the laser diode is dead, this is a common issue on these old machines.Try to decrease the resistance by adjusting the trimmer on the CD assy, this sometimes can give a bit of  further life to the diode.

[miisalo]

I was afraid that voltages are correct, I measured (and recapped just to be sure) all PSU caps today and checked the circuit and it seems to be good and your values confirm it.

Thanks for the info. I'll see what I can do with it. Does not hurt to measure ESR of the cap in the CD assy either 

CD spins just a bit when I start the console (or shut it down) and laser moves slightly if I press same time the cd tray closed switch.

[miisalo]

Recapped the CD drive. There was one cap that had leaked a bit and one or two with bit lower capacitance than the spec but no luck with those replaced. Turning the pot on CD drive makes the disc spin for a while when pressing the closed switch but even fully turning the pot does not make it read disk. Looks like replacing the diode might be the only answer and is that feasible?

[caius]

Recapped the CD drive. There was one cap that had leaked a bit and one or two with bit lower capacitance than the spec but no luck with those replaced. Turning the pot on CD drive makes the disc spin for a while when pressing the closed switch but even fully turning the pot does not make it read disk. Looks like replacing the diode might be the only answer and is that feasible?

Replacing the diode is pretty impossible.You should change the whole laser assembly, there is thread about in this forum.It seems the Marty one is from Panasonic.

[miisalo]

Success!

As I said, turning the pot didn't not make it work but after that it seemed to at least start to read because it spinned the cd normally for few seconds. Turned out that the laser mechanism was also jamming and it could not move the head. I used bit force and now it works laser pot turned just tiny bit from the original spot.

Thanks again for the advice.

[Dr.Wily]

Bump this topic !

I have a similar issue with a Marty. The CD drive make a electric buzzing sound, CD is spining, laser is on but the Marty can't read CD.

It's may be a defect motor driver, but I am not sure. Someone has already encounter this issue ?

[caius]

As start do a full recap (motherboard, PSU and drive PCB)

[Dr.Wily]

Full recap done... with no good result. I also change the motor driver but same result. The drive spin for a while and stop without reading data. Any other advice ?