Glowworm Micron 50FF components

[Bob Mannix]

Wot I need is someone who has a circuit diagram and can tell me what the specification of the temperature setting pot on the PCB of this boiler is (new green LED PCB).

Boiler water carries on getting hotter and hotter until elderly pump starts complaining (pump OK at lower temperatures). Changed thermistor, as it's cheaper than PCB, but no change (measured old one in the end and nowt wrong with that either). Measured temperature setting pot which seems to be open circuit in the middle 30% of its range and bizarre either side. Object to paying £124 for a new PCB if it's just a pot!

Any boiler anoraks out there with a circuit diagram/parts list? Can't remove part as want boiler to function (as best it can).

[Jon]

I got a replacement Micron PCB off ebay for =A330 in Jan and fixed my boiler. Brand new genuine part.

There's a guy who posts here who refurbs the PCB's, so he may be able to help.

[geoff]

In message , Bob Mannix writes

Do you mean the interconnection diagram ?

It won't give a linear reading, it's part of a chain

No

better ring me tomorrow

phone number on the website -

[Bob Mannix]

Well I meant a circuit diagram but we may mean the same thing! I don't want how the boiler parts are connected together but the circuit diagram for the PCB.

That wouldn't explain open circuit in the centre of the travel. I'm guessing its (probably) a 0-20k linear pot but that's only a guess, as the thermistor is 2.5k-14k across its dynamic range and, intuitively, one might assume them to be similar (while holding to the maxim that assumption is the mother of all c*ck-ups!). Yes, removing it would be better but, with it right down to zero on the dial, I can just about keep things running at present so didn't want to remove it. I made my measurements with the board itself removed and disconnected, of course.

I am bidding for a new PCB on ebay at present, which would be quicker, but many thanks for the offer - I may take it up if the bid fails!

[Bob Mannix]

Or, indeed, a reconditioned one from you, I should have added! I have bookmarked the page!

Cheers,

[geoff]

In message , Bob Mannix writes

Your chance is probably somewhere between nought and zero

Also, there are two different versions of the board - the old version with discrete components and 6 neons on the pcb, and the later version(s) with 2 green LEDs and not a lot else other than two PICs (version 3 has a microcontroller)

It's stamped on the pot