QL's external MDV port

[1024MAK]

These need adding per external QL Microdrive:-
TR4 / TR5 = BC184
TR6 / TR7 = ZTX551
D16 / D17 = 1N4148
C19 / C20 = 47nF
C21 / C22 = 22uF
R26 / R27 = 3.3K
R28 / R29 = 1K
R32 / R33 = 820R
R105 / R106 = 1K
D20 / D21 = LED
(Only one of each, two component ID's listed, as the QL main board has two of each, one for each Microdrive).

See the schematics (available here).

Mark

[tcat]

Hi Mark,

Thank you.
I wonder what difference it makes, if I connected Issue#5 MD Unit to the external port of Issue#6 QL Main Board?

Many thanks so far.

Tomas

[1024MAK]

The listed items are mainly for controlling the motor and the drive active LED...

Mark

[tcat]

Hi Mark,

Thank you.
Would you know how to adjust drive motor speed, as my MDV2_ appears a wee bit faster to MDV1_.
Many thanks so far.

Tomas

[Martin_Head]

A lot of the little 'tape recorder' motors had a hole in the bottom for adjusting the motor speed (may be covered with a label). I don't know if the QL one's are like this.

Unless the speed is way off and causing problems swapping cartridges between the two drives. I would tend to leave well alone. If you start fiddling with it, you may not be able to put it back as it was, and end up with more problems.

Martin Head

[Ralf R.]

A lot of the little 'tape recorder' motors had a hole in the bottom for adjusting the motor speed (may be covered with a label). I don't know if the QL one's are like this.

Unless the speed is way off and causing problems swapping cartridges between the two drives. I would tend to leave well alone. If you start fiddling with it, you may not be able to put it back as it was, and end up with more problems.

Martin Head

I have experimented with this (long years ago) and have found out, that changing the speed higher gave up to 245 sectors for newly formatted cartridges. Ok, just wth my motor .

[tofro]

Most cases I've seen in the past (when I still had some working tapes), the tape speed depended much more on mechanical adjustments than on any electronic parameters. Actually, there are no means to adjust the speed through a potentiometer or anything, if you are asking for that. You would need to replace the resistors and caps in the motor driver circuitry.

But anyhow: The microdrive hard- and software is designed to be very well able to cope with varying tape speeds - Even if you got your drives to work at the exact same speed, you couldn't adjust anybody else's I would just leave it as it is and be happy with it

Tobias

[tofro]

I have experimented with this (long years ago) and have found out, that changing the speed higher gave up to 245 sectors for newly formatted cartridges. Ok, just wth my motor .

Very unlikely, Ralf, your memory might trick you. Actually, you'd need to have the tape running slower instead of faster to get more sectors onto it. Think about it.

Tobias

[1024MAK]

There is no electronic speed control on the QL's main board or the Sinclair Microdrive PCB's.
However, see this later post for details of the actual motor.

Mark

[Ralf R.]

I have experimented with this (long years ago) and have found out, that changing the speed higher gave up to 245 sectors for newly formatted cartridges. Ok, just wth my motor .

Very unlikely, Ralf, your memory might trick you. Actually, you'd need to have the tape running slower instead of faster to get more sectors onto it. Think about it.

Tobias

No, I know it. I am unsure if more slow or more fast, but I have set it to get 245 sectors. And it was able to read all other mdv. I had built a QL in a separate case and wanted to use one mdv for drive 1 and 2. And this is possible if you put a germanium diode in the drive select line. Then you can use one mdv for 1 and 2.