In message
T i m wrote:

On Fri, 18 Sep 2020 18:26:25 +0100, John Bryan
wrote:

snip

Eh? So the knobs don't work 'normally', only when in setting mode?

Oops missed this one

Well, there were quite a few questions. ;-)

Yes you can turn the knobs until the cows come home and it will not change
anything. Only when the knob is pressed in and a digit is flashing.

Ah, got it.

I presume pressing the knob signals the control circuit and enables the
knob encoder to change something.

Yes, probably good if you were to nudge them round by mistake. [1]

Cheers, T i m

[1] Years ago I was having the physiotherapy on my back for a trapped
nerve and had a session of electro therapy, electrodes suck on my back
and hooked up to a machine causing my back muscles to contract and
release at a couple of second intervals.

Laying on my front, machine on a trolley by my head hands and me on my
elbows, left to 'turn the voltage level up, as / when you can handle
it' .. .

She left me set on level 3 of 10 and I'd slowly got it up up about 5
when, as I'd just got my hand on the level knob my elbow slipped off
the end of the bed and I span it round to 10!

Now, whilst I could just about cope with the pain, I initially
couldn't recover enough between bursts to get my hands back on the
machine to turn it down (but after a few goes I did). Now, if you had
to press the knob in fist, that wouldn't have happened. ;-(

Would have thought this should have been a stepped switch to prevent just
this. I take you survived this misfortune and are now worse for it.
I felt for you when I read your recollection.

I had to endure a bout of Physio terrorism and did ask to see their big
book of 1001 Ways To Inflict Pain (available in hardback)...
Ha Ha only joking

--
John Bryan