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hbsoftware
September 11th, 2017, 04:15 PM
greetings to all
first of all let me tell you English is not my native language so sorry for any errors that my text may contain.
I recently purchased an Amstrad PC1512 wich i want to restore and it came with a 20mb MFM Tandon drive , model TM262, its is a rebadged western digital i think
the drive was disconnected from the power and when i connected it it does not spin or seek

i took it out of the computer and removed the drive's pcb. the platters are not stuck neither the stepper motor, i still lubricated the bearings were i could acess them and noticed a big improvement when trying to move the heads by rotating the stepper shaft with my fingers, so no stiction problems, they are very free-moving when compared to a working seagate 10mb drive i have
visual inspection of the board gives me no clues , no visible damage or cold solder joints

when i power the drive outside the pc with an atx power supply i have at hand i hear a relay clicking, the drive heads step a few degrees no matter were i position them before applying power and it just does not spin
i tested the voltages at the power supply molex connector and both 5 and 12v are present
the pcb contains some tantalum capacitors maybe i will exchange them since they maybe prone to fail....??
otherwise the board has just a bunch of resistors and ICS, a relay wich tests fine and a zener diode wich i am not sure how to test properly
(i have very basic electronic knowledge however i am good at following schematics and can solder preety well) i only have a multimeter as my test equipment, no scope or esr meter etc

can anyone please shed me some light on this?i suspect a pcb failure but its just my instinct...stiction is definetely ruled out
i do not want to start desoldering every componet to test it, i would like to know were to start but i have no clue, i am more familiar with washing machine electronics and on them i can see wich component does what but on a hard drive i really cant estabilish a troubleshooting route.

modem7
September 13th, 2017, 01:36 AM
greetings to all
Welcome to these forums.


... the drive was disconnected from the power and when i connected it it does not spin or seek
Normally, hard drives not allow movement of the heads until the spindle is up-to-speed.

On every "MFM" drive I have seen, simply applying power starts the spindle turning. And the TM262 appears to be no exception, because in the TM262/362 user's manual is, "The microprocessor starts the spindle motor when both voltages are present."

So, in my opinion, the 'spindle not spinning' symptom is the one to concentrate on.


(i have very basic electronic knowledge however i am good at following schematics and can solder preety well)
Maybe you start constructing a schematic for yourself by working back from the spindle motor.

Also in the manual is, "If the spindle motor does not get up to speed within 15 seconds, the drivers to the spindle motor will be turned off."

It sounds like the block diagram is going to be : MICROPROCESSOR --> DRIVERS --> SPINDLE MOTOR --> ROTATION SENSOR --> MICROPROCESSOR

hbsoftware
September 20th, 2017, 04:43 AM
thank you modem 7 for your reply, so i will try to identify the chips on the pcb to see wich one is the microprocessor but without a scope all i can do is maybe search for broken traces with the multimeter
the spindle motor drivers maybe i can test them i wil google that and i see a rotation sensor maybe it is hall effect??? i will also check that out but i do not have much hope at this point...although i really want to put this thing working i have limited tools and basic know how

what is your opinion on the tantalum caps?none of them is shorted, i checked it already