The Sinclair QL Forum

Hi everyone,

So here it is... both MDV of my QL are behaving badly. MDV2 never worked since I get the QL: when I do a DIR mdv2_, it starts spinning and it does not stop until I hit the reset button.
MDV1 did work (at least to some extent, I managed to get contents of one of my cartridges, the rest of cartridgs seem not to be working), but today after trying to format a newly felted MDV, it gives me "format failed" message (BTW, I have not tried to format using mdv2_ only mdv1_).

To my surprise, when issued "dir mdv1_" command, MDV1 starts spinning and never ends...

I've checked viewtopic.php?f=11&t=3178 thread carefully , but I have doubts about what the culprit might be, and before disassembling the QL I wanted to know your opinion:
* My first bet was 7805 regulators + electrolytic associated capacitors. If I need to replace 7805 I'll probably replace capacitors as well.
* I fear it would be the ULAs (but both failing the same way??).
* TR4 + TR6, TR5 + TR7, but again, all af them failing the same way?

Thanks in advance!

Hello everyone,

Some feedback about this issue. Finally opened the QL and found that C35 capacitor had one of its legs cut. It was an apparent attempt to re-attach that cut leg by soldering but after some time it broke again, I guess.
I also took the chance to reflow TV modulator connections which broke as well.

Going back to the microdrives issue, I measured at both regulators their output voltages and mdv1_ was 5.0 something and mdv2_ 4.86, so I guess regulators are working good enough. I cleaned thoroghly both tape heads and I got a couple of NOS cartridges.
I'll probably go on with investigation, but I'd really appreciate some clues here.

All the best!

Perhaps the following topic may help:

https://www.theqlforum.com/viewtopic.php ... ive#p29431

Cristian wrote:Perhaps the following topic may help:

https://www.theqlforum.com/viewtopic.php ... ive#p29431

Thanks Christian!

Somehow things have improved. I managed to format one microdrive re-felted and could get the directory. So far, I managed to read three microdrives NOS.

I don't think C35 capacitor has something to do as it is in the RF modulator. Also reflowing RF modulator hasn't affected the mdv.
My guess is that re-seating mdv connectors to main PCB, with cleaning microdrives' tape heads has done the trick.
My first cartridges are quite degraded.

mdv2_ works pretty well, it is able to format, mdv1_ is quite unreliable.

All the best!

JupiterJones wrote: Thanks Christian!

De nada, JupiterJones.
If you use Minerva ROM, also the following discussion may be useful:

https://www.theqlforum.com/viewtopic.php ... 128#p25227

Cristian wrote:

JupiterJones wrote: Thanks Christian!

De nada, JupiterJones.
If you use Minerva ROM, also the following discussion may be useful:

https://www.theqlforum.com/viewtopic.php ... 128#p25227

Thanks again! Unfortunately I don't have Minerva ROM yet. I've read that thread and the solution provided looks very Minera-specific.

I'm just waiting for a vDrive at the moment with the vMap modification, so I'm still unsure about I'll do the next. I'd probably swap the drives, and just maybe I'll replace microdrive board electrolytic capacitors if I had the time because I read in the forum that this may help.

My main target now is to load programs reliably and start exploring QL software.

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