View Full Version : Commodore 64 1541 disk drive problems

February 19th, 2008, 12:33 PM
I have a 1541 disk drive which will power up, red drive light comes on, then goes off.
from what i can remember the drive should spin the motor inside for about 2 seconds to check it ok, but nothing happens.
If i try to load a disk i get the usual searching promt from the c64 but the motor won't engage, after a short while i get (file not found) on the c64 and then i get a constant flashing red light on the drive.
iv'e check the drive head is sitting in the right place and would like to check the voltage thats coming from the motor controller, but don't know what the voltage should be for each wire that goes to the motor.

i have a PCB No. 251830 mother board and the motor controller is the newtronics type.

any help would be great


February 19th, 2008, 12:43 PM
The motor takes 12V, the logic board takes 5V. I'm not sure about the individual pinout on the cables though.

February 19th, 2008, 01:36 PM
The motor takes 12V, the logic board takes 5V. I'm not sure about the individual pinout on the cables though.

Cheers carlsson,

dunno if thats a good thing or bad because i seem to be getting 12v to the motor so i think that means there something else wrong with the drive.
do you think it could be the sensor that see's where the head is positioned, i'm just grabbing at straws now.


February 19th, 2008, 07:35 PM
Here's a link to a 1541 service manual.


It doesn't seem to have your particular board number, but, perhaps you are reading the wrong number

Hope This Helps

Terry Yager
February 19th, 2008, 10:06 PM
Is this something you've had working before, or did you just pick it up in that condition? If it's unknown to you, you might want to check the device select jumper.


February 20th, 2008, 12:39 AM
If he gets ?FILE NOT FOUND and a flashing light on the drive, at least the communication between the computer and drive is working, i.e. it has the right device number. Otherwise he would get ?DEVICE NOT PRESENT from the 64.

As for other ideas, I believe the 6522 chips are candidates to get fried. If you have a source of a spare 6522 VIA (i.e. another 1541, VIC-20, PET and so on) it could be worthwhile to swap chips unless the controller board itself is shot so it would kill those chips.

Apart from the service manual, Ray Carlsen yet again has some troubleshooting tips on his page, scroll down a little:

February 20th, 2008, 03:29 PM
Thanks for your help guys, i found this and it describes my fault

When drive powered up or reset, red LED comes on and goes out,
but spindle motor does not turn. When LOAD attempted, spindle does not
turn, red LED flickers, screen displays "FILE NOT FOUND" and red LED


but it labels the chip as UF5 325572-01 MOTOR CONTROLLER (PLA) which i don't have but found a chip with the same number 325572-01, on my board and it's the UC1 chip.

also the 3 pin connector which goes from the main board to the motor controller seems to have low voltage, i barely get 4 volts from it and the motor should be 12volts, so i think it's definitly the uc1 chip not providing enough voltage to the motor.

also the first number i quoted was the PCB No. 251830 but it also has the number 250442-01 which i think is the board number.

p.s the motor definitly works hooked it up to a power supply and spins fine.

will keep you posted.