Slow QL

[t0nyt]

It turns out it's a case of RTFM!

Charlie covers this in troubleshooting, and his test for the reason is in the vDrive manual

Seems one of the MDV's is missing a mod, time to work out which one it is

Many thanks

[t0nyt]

It turns out it's a case of RTFM!

Charlie covers this in troubleshooting, and his test for the reason is in the vDrive manual

Seems one of the MDV's is missing a mod, time to work out which one it is

Many thanks

Oh well, that diode fix doesn’t work for me

At least I now know I can put any old cart in the mdv’s to load the vdrive/vMap software until I can find a new QL

[Martin_Head]

Re the glowing mdv light. I have had a quick look at the circuit diagram https://www.sinclairql.net/srv/QLSchematicIssue5.gif

If the glowing light moves with the mdv unit. I would suspect the ULA on the back of the mdv unit. It looks like the motor/LED is driven from the COMS OUT signal (pin 20) of the ULA. I suspect that this is floating about, not high enough to drive the motor, but enough to light the LED a bit.

This would also account for the Vdrive problems. As this COMS OUT signal is daisy chained to next mdv units COMMS IN and then out to the Vdrive's COMMS IN.

If the mdv unit with the bad ULA is set as mdv2, then you might find that mdv1 and mdv2 seem to work OK. But any drive past that will not.
So with the bad mdv unit set as mdv1, mdv1 may work, but mdv2 will not.

You also say that the ZX8302 is faulty, Well the COMMS IN signal to the mdv unit comes from the ZX8302. So there's a connection between the two problems you have.

[t0nyt]

Re the glowing mdv light. I have had a quick look at the circuit diagram https://www.sinclairql.net/srv/QLSchematicIssue5.gif

If the glowing light moves with the mdv unit. I would suspect the ULA on the back of the mdv unit. It looks like the motor/LED is driven from the COMS OUT signal (pin 20) of the ULA. I suspect that this is floating about, not high enough to drive the motor, but enough to light the LED a bit.

This would also account for the Vdrive problems. As this COMS OUT signal is daisy chained to next mdv units COMMS IN and then out to the Vdrive's COMMS IN.

If the mdv unit with the bad ULA is set as mdv2, then you might find that mdv1 and mdv2 seem to work OK. But any drive past that will not.
So with the bad mdv unit set as mdv1, mdv1 may work, but mdv2 will not.

You also say that the ZX8302 is faulty, Well the COMMS IN signal to the mdv unit comes from the ZX8302. So there's a connection between the two problems you have.

Thanks Martin

Since fitting the diode mod the LED glow has gone away

It’s currently set as MDV1 and MDV1/MDV2 appear to be fully working and I can access the vdrive as MDV3

The outstanding issue is the vdrive software not finding the vdrive, but if I stick a Cartridge in either MDV1/MDV2 then the vdrive software finds the vdrive ok

I’ve ordered some new diodes in case the one I fitted is faulty (took it from a spare mdv unit)

EDIT: Not sure I’m up to fitting a replacement ULA

Many thanks

[t0nyt]

Replaced the Diode with a new one, but still won't initialise with that MDV fitted

Will make do with putting a cart in one of the drives for now until I get around to sourcing another QL (or another working MDV unit) as it's the spare

Many thanks

[t0nyt]

I seem to have got it working now without having to put a cartridge in by “reversing the flow of the flux capacitor” (diode) to the opposite of what’s shown in the image in the instructions (maybe my diodes are marked the opposite way around?)

Both physical drives are working (including format) but the vDrive seems to take a couple of attempts to initialise the software (does happen on main QL sometimes). Will do some more testing though

Many thanks

EDIT: all seems good now, although the slight LED glow is back