The Sinclair QL Forum

Hi everyone!

So, as I make more use of the QL-SD on my BBQL, I decided to re-wire the MDV2 (red) LED to the QL-SD daughter-card, in place of the pink LED pre-soldered to the daughter-board.

However, even after carefully checking polarity and checking the LED itself was still working, the MDV LED refuses to light-up at all upon SD access.

I'm suspecting a lower voltage on the SD-Card daughter-board or something similar.

Any ideas?

Martyn,

actually, nearly everything on the the QL-SD runs at 3.3V - Including the LED.

Are you sure there's no left-over resistor anywhere in the QL circuitry?

You might want to have a look at the attached schematic to make sure you got it right.....

Tobias

Aha!

Thank you Tobias - if only I had checked the schematic first!

I had thought I'd measured one leg of the LED at GND, (the other end connected to the limiting resistor), and hence oriented my (ex MDV) LED accordingly.

I see now that the LED is fitted between +3.3v and the limiting resistor (then to GND).

I'll reverse the orientation and try again.

Glad I asked!

M.

Hi Tobias

Just to close the loop - yes, simply reversing my (mistaken) connection to the LED resolved the issue!

I must remember to RTFM in future!

M.