The Sinclair QL Forum

Hey Andrew,

Exactly what I was looking for - thank you sir!

Mark.

Hi all,

I've been looking around to see if I can find a decent picture of where the diode mod goes on the QL microdrive PCBs.. Does anyone have a decent picture of the diode in-situ? I can see that the negative side of the 1N4148 looks like it goes to the closest leg of R100/102 and the positive ...

Quick update...

SO removing the 74LS00, both JM EPROMS and the associated wires and re-installing the 0R links, it did the job. Thanks for the info!

KbJ

Thanks! I'll go have a look.

Cheers,

KbJ

Hey all,

I picked up a Minerva+TKII EPROM adapter board from Chr$ and went to install it in my QL - it's an issue 5 board with the 2 JM EPROMS with the 74LS00 and the rats nest of wires going from the EPROM's to the 74LS00..

Have anyone fitted a replacement ROM board to an issue 5 QL like this? I ...

Hey everyone,

Thanks for all the pointers and help with my QL. Just a small update..

I replaced the caps on the MDV PCB (electrolytics) with the caps mentioned here.. and no dice. :-(

I then replaced 2 transistors on the motherboard and also the 1N4148 at D28.. and the MDV will read sometimes ...

And the caps arrived.. still nothing.. time to look some more..

I'll maybe break the scope out and check the waveforms on the new ULA to make sure that's working..

M

Hey Nasta,

Thanks for the heads up - I've ordered some 220nF and 470nF polyester film caps - for all the cost, I'll replace them and see where that takes me.

Hopefully it's not the head..

Cheers,

Mark.

Hey all,

The reason for looking at the transistors/diodes is that the MDV2 motor 'sounds' like it's running slower than MDV1's motor. When spinning, it's much lower pitched (that's the only way I can describe it) - is that even a thing? I'm sure that the drives have to spin at the correct speed to ...

Ahhh - ok, I was under the impression that it was good practice to replace those caps if the MDV was misbehaving.

I've got a QL that has an MDV2 that won't read / write / format anything. It just spins forever. Carts can be read/written/formatted in MDV1 just fine. Checked all the voltages (5v was ...