t0nyt wrote: Thu Feb 15, 2024 9:47 am
Thanks Tofro, but I don’t know much about this kind of stuff
I assume I put the red probe as per the chart, but do I use a single ground point for the black probe please?
Many thanks
Because you need to ask: Don't accidentally connect pins when you set the probes, they need to go where indicated and exactly there, or you may fry important components. If you feel unsure, refer to the first sentence of my answer, and if the QL seems to work, there's actually no need to fiddle with it, there's nothing to gain from it.
I agree with your advice (and take it onboard), but I need to take some readings for Charlie (vRetro) to try and get to the bottom of why the vRetro PSU I purchased won’t work properly with my QL’s
I’m between a rock and a hard place really, so will have to think about this carefully before proceeding
Pr0f wrote: Thu Feb 15, 2024 1:20 pm
What's the symptoms with the vRetro psu?
Whenever you apply power to the PSU, and press the button to turn it on, the QL (this all applies to both QLs) power light comes on but nothing else happens. You have to turn the vRetro PSU off/on again to get the QL’s working. This applies every time you turn the input supply walwart to the vRetro PSU off/on
Once working you can turn the vRetro PSU off/on (as long as you leave its input power applied) or reset the QL and it’s only intermittently dying
With Trump card installed it doesn’t start at all (other than QL power light)
The walwarts i’ve tried for the input power are all within specs
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 more than enough juice to power up the QL with or without an expansion card in it.
My only criticism of this excellent device (apart from cost of shipping to the UK) is that the button on top is sometimes a bit unresponsive, but a good press on it seems to do the trick, so it may just be me.
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 am fairly sure he overdesigned it a bit, as he would probably have got away with a squarewave, but that carries it's own problems of signal radiation into neighboring circuits.
It does mean that cheaper multimeters can misread the voltage level output of this, as they don't do a proper RMS calculation.
) the vRetro will gracefully abort trying to power the QL up.