QL not talking to microdrives

[RWAP]

This is rather an odd question...

A customer has been experimenting with his QL - adding a Super Gold Card and trying out SMSQ/e on it .
However, he then went on to try loading software from microdrive and found that they did not respond.

OK - so SMSQ/e does not support microdrives (from memory), but even without the Super Gold Card connected, DIR mdv1_ / DIR mdv2_ does nothing whatsoever...

Any suggestions?

It could be a loose microdrive cable - but beyond that, I don't know what else to suggest!

[tofro]

Rich,
if I recall it right, the Microdrives (+ serial interfaces) are the only parts in the QL that would require a working +-12V supply (cooked from the 9V DC from the power supply).

So it could either be the 9VAC from the power supply are gone, or the +-12V generation circuits would be broken.

1. Check if Serial ports still work
2. Check 9V AC supply from power brick
3. Check if +-12V available on the mainboard.

Less obvious (but more complicated) would be the driver circuits of the MD themselves, but I can hardly imagine that both drives' circuitry would suffer from the same problem.

Regards,
Tobias

[Dave]

The power supply has a 9vDC rail to power the QL and a 15.6V AC rail to regulate and run the microdrive motors, FYI. If the 15.6V rail or any of that regulatory circuitry is duff, the MDVs will both not respond.

[tofro]

Right Dave, messed that 9V part up. Anyhow, I would guess the A.C. is gone from the power pack.

8.1 A custom-built power pack, external to the main board, supplies 9volts d.c. at 2amps and 44 volts peak-to-peak a.c. to the board input on connector J3. The power pack uses a thyristor to limit peak voltages on the d.c. , but is otherwise unregulated and has significant ripple.
8.2 The a.c. input is applied to two rectifiers IC37 and IC36 to produce +12volts at 80 milliamps and -12 volts at 50 milliamps,respectively.

So it's either the brick, cable, connector or IC36/37.

Regards,
Tobias

[RWAP]

It could also be the regulator...

My guess is that he disturbed the microdrive cables when fitting the JS ROMs - if the necessary signal is not there for mdv1_, then the QL will ignore mdv2_ !!

[Dave]

Why does this remind me of a Monty Python sketch?