The Sinclair QL Forum

The only issue I could see is that some of the older switching regulator circuits operate in the lower frequencies and might produce radiated interference that could affect the microdrives, but more modern designs use very high KHz or even MHz range and so this is less likely going to be an issue. A...

That's nice

No photo's I'm afraid - but if you look at the issue 5 board - there is a wire link or zero ohm resistor that connects pin 40 to VCC - it's marked on the PCB as a diode - and that's the first clue - this is the VCC for battery - which should be a wired or'd pair of diodes - one that from VCC to pin ...

The battery area was under the heatsink and near the modulator - but I've never seen a board fitted with it. I did make this mod myself on and old QL, but it involves some tweaking with the reset signal during power up - if I did it again I'd use one of the power management chips that locks out the ...

That should be more than enough I would have thought

One thing I would say - Charlies vRetro uses some sort of stepped square wave format for the AC voltage - it works fine with the power circuity in the QL for generating +/- 12V using the small L series TO92 regulators (look like transistors), and I don't think this AC voltage is used any where else ...

I know that if I have too much plugged in (curse those backplanes :-) ) the vRetro will gracefully abort trying to power the QL up. but it will happily run one expansion card in the QL no problem. I can't remember what spec my little power supply is, but I think it's 12V at 2.5A - which provides mor...

What's the symptoms with the vRetro psu?

But the input to the 5V regulator should be about 9V DC I always thought (and have measured - when the QL is on). The regulator will work if the voltage is about 1-1.5V above the output voltage of 5V.

Yes - if using a multimeter - put the black lead on ground - a good place that's convenient is the modulator housing, and then use the red probe to take your readings - but if the voltage you are measuring is AC - then you will need to switch the multimeter to AC range for that reading. You will get...