The temperature sensor could be a simple diode. Reverse biased they make a very cheap, simple and fairly accurate sensor. That lead out of the toroid could be a sensor, or a once only go/nogo sensor.
I asked a proper electronic engineer to have a look and he reckons it's a thermofuse. Which having looked at the AJ makes sense, as they're both no resistance.
Does it have a resistance to the primary/secondary? That could fit in with the darlington.
I'll have a look next month. It has a ground and a iirc 560Ω to the darlington common out.
I've taken my motor outtov dry dock and I'm living outtov that off grid style for the rest of the month. The house system project isn't a massive priority I spend half the year off grid already.
I may give yous a tour of her electrical system one of these days if I have some time to post.
It's a bit embarrassing given the standard of execution of installation...trouble is it works so bloomin' well there's no good reason to pull it apart to add a few compression glands, conduit and tidy it up.
1 UPS I have got a bit warm (aka I could smell the varnish and it was melting)The internal sensor went s/c. I cant replace it as it is inside, so it's now a 10k resistor and a large warning notice.
Yurp I thought about doing something similar but I thought it'd be better offset the temp reduction to a less than ideal location and fit a new sensor as close as I could get with kapton tape.
Those resistors need inserting, I'd say. They don't look like dry joints (so might have dropped out). Manufacturing defect. I'd be tempted to send the pic to Studer
and ask for QA comment
Both myself and my EE friend agree. Wave flow process failure.
Good idea...I think I'll use it as a bargaining chip to get a schematic outtov 'em.
Earth strap. Please tell me you have a 1M resistor in the plug top, else you are angling for a proper belt across the heart. Or fit it to an ankle, but be prepared for it to trip you up!
Whadya take me for...some kinda cowboy, circuit bending, hack?
Don't answer that! Of course there's a 1 MΩ in there...

Ladies and gentlemen as a token of my gratitude and esteem everyone who has purchased an ESD safety armband from me is getting a free lekytronic project kit!
It contains
lead free free lead solder, a 1 MΩ resistor, heat-shrink, a cable tie and a stylish resealable bag!

and behold our latest innovation!
Cheap-a$$ meter fuses.
How many of you have spent more on HRC fuses than most people spend on multi-meters?
Why do you need a high rupture capacity fuse rated for medium voltage when yer gonna blow the bloomin' thing on extra low voltage every time?
Roll up roll up....Well-err...look no further I have the fuse for you...
Fits all standard Flukes and other posh meters!

You can get the proper thing for £1 from china with the resistor built in. Hmm, unless that is a small clip and a small loop of wire.
Jonesy...shhh...man's gotta eat...

Bracing for criticism. Does the back box need earthing? I have since lugs were fitted, but the screw heads pick up earth from the socket. IIRC light switches dont earth the heads.
Lights are different, they're not metal, they live in the air and they're not so user interactable.
Need earthing I think not...unless my neighbour goes for a Darwin award setting shelf anchors with an SDS.
However...
Was a contractor paid to earth it? Is he lawfully obliged to earth it? Did he do the rest (some clamped some loose)? Did he sign off on having done it?
How tired do you think I get of being told to hire a registered contractor to carry out electrical works because I'm only legally allowed to fix the job after him?
Did I mention it's a ring main?

...before my time..
Are you still using lead solder? I went lead free last century, but avoid the fumes anyway. I keep a roll of leaded around as it melts at a lower temp and flows better.
Yurp.
I use trichloroethane or MEK for flux removal or IPA if I don't want my fingers to melt. Acetone aint bad and comes in 1L bottles for 1€ here.
I can't imagine where that unit was installed for that dusty layer. Was it conducting, or just carp from a self destructing fan. The fans should be installed to suck in the air through a filter, then the exhaust will push warm air out of any available orifices. Do it the other way and you suck in carp through gaps.
IPA was flashing white krudd and sticky staining.
Ever been in a metal fabricators? That kinda filth. Grinder dust and atomised metals, sticky in places.
Fan was operational but it had as much travel on the Z axis as the X and Y. Well they were suckers not blowers.
eblaggers that lie about products really get my goat;
Scumbags....
Item condition:
For parts or not working
“removed from an old off grid installation, was working before we removed it, untested since.
this auction is for a used and untested 6kw 48v inverter charger from Studer. Includes battery temp sensor and controller.
Studer make some of the best quality inverters on the market. This Swiss brand are well known for the quality.
Taken from another website that sells these new..
We removed this unit from an off grid house and upgraded it in capacity terms. Before this was removed it was working without any issues and if more capacity was not required I'm sure it would still be there. "
It's from a company most people would recognise that has all the usual not fit for purpose Chinese tat and car batteries with leisure stickers.
Nice use of the back light.
Yeah...depends on how double sided the PCB is...a lottov the time the rearside trace blocks the light turns out.