TM848 repair?

Jim Brain brain at
Mon Jul 13 14:21:24 CDT 2020

On 7/13/2020 2:02 PM, Chuck Guzis via cctalk wrote:
> On 7/13/20 11:18 AM, Jim Brain via cctalk wrote:
>> The Tandon 848 is not one of my favorite drives.  There is an option not
>> to pass the Motor On/ signal unless a disk is loaded and the drive door
>> is closed.  Check U16 pin 8, which should be high for MOTOR ON.
I will do so.
>> It seems more like an oversight that all 4 drives don't spin.  Be aware
>> that the 848's motor controls are different from 5.25", where one line
>> controls all motors.  The 848 uses pins 4,6,8 and 24 on the interface to
>> control the motor--each drive has a jumper that dictates which line will
>> be used. (MC 1-4).

Yep, one of the drives was set to DS2, so I moved it back to DS1 so I 
could test as a primary drive.  I agree the drives would be different 
from 5.25" ones, but I connected them to the same PSU that runs my 
TM848E successfully.  It seems strange that a working PSU that drives a 
TM848E would not supply enough or the right voltage for a TM848-02.


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