Twin Famicom disc drive mystery issue

[andrewpattie_music]

Hi folks,
First time posting here. I've been working on a Twin famicom. It came to me as completely broken. Turns out it was a replacement PPU and RAM chip to fix the picture. Fami side works great. Now, on to the FDS side. Initially I thought it was just a quick belt change and calibration but still showing error 20,21 and 22. I have 3 spare drives in total and a working FDS. I tested all the drives on that. They all work fine, booting first time. No errors.
Why is the Twin disc side failing? Is it the SRAM chip or drop in voltage to motor? I'm at a loss. If anyone can help if be very grateful.

Andrew

[fredJ]

I have never heard or experienced a disc drive having chip problems. I guess it is possible.
Does the motor move at a good pace?
Are you 100% sure it is not a calibration issue? Sometimes someone else might have fiddled around with it before you got it. If you try to fiddle with it, you should at least get other error codes.

you can try to replace some parts of it one by one, to see where the fault is. The motor is not hard to replace, if I remember correctly, or the circuit board. But my guess is that you would still have the same problem, I think it comes down to the calibration.

If you need spare parts, broken disk systems aren't expensive.

[Skawo]

The FDS and the Twin Fami have a potentiometer on the board which adjusts the drive speed (in addition to the one in the motor itself). Maybe it's not set right in your Twin.