Circuit diagram for drive EME-157 anywhere?

[llopis]

I have a floppy drive from a 6128 Plus that's pretty dead. No spinning of motor at all. It's getting correct voltajes and there are no dry solder joints, but the spin motor itself isn't getting any voltaje to activate it.


I suspect someone plugged in some incorrect power supply in this computer and blew up everything, including the drive. Is there a circuit diagram for this drive (EME-157) anywhere? It's different enough from the one described in the CPC 6128 Service Manual that makes it pretty worthless.

[gerald]

I have a floppy drive from a 6128 Plus that's pretty dead. No spinning of motor at all. It's getting correct voltajes and there are no dry solder joints, but the spin motor itself isn't getting any voltaje to activate it.


I suspect someone plugged in some incorrect power supply in this computer and blew up everything, including the drive. Is there a circuit diagram for this drive (EME-157) anywhere? It's different enough from the one described in the CPC 6128 Service Manual that makes it pretty worthless.

I do not know any source for the EME157 schematic, but looking at the PCB, its clear that it is driven quite like on other drive : a power PNP transistor (Q1) driven by a smaller NPN one (Q2). Q1 base current limited by R3.
Q2 is a bit special as it integrate base polarisation transistor (datasheet here : http://rohmfs.rohm.com/en/products/databook/datasheet/discrete/transistor/digital/dtc144eetl-e.pdf (DTC144EKA))
The difference with other drive is that Q1 base is driven by IC1 pin 20 instead of the motor ON pin. When this pin is high, the motor is ON.