I haven't found a source of new old stock at that price but am waiting for a reply from someone apparently with a new unused one for quite a low price. I think one of the signs that is is unused may well be lack of browning around the BZT diodes mentioned but am probably not going to start taking it apart when I go to collect it to check this. I may just have to trust the seller. The one in use now has a spent battery (resets after a power cut) and although it is probably the easily replaceable type battery one am not going to mess around with it as it is working perfectly otherwise. Knowing my luck trying to replace the battery will finish the unit off for good! I want the spares as if I am not around don't want the family to be messing around and waiting for a new type programmer to have to be wired in. Obviously they know where to and they have to switch the power to the unit off (and take out the fuse for good measure ) and can clip a new one on. The room thermostat is also the old Drayton Digistat 1 which can be replaced in the same way if needed and I have a used one of this as well as a BNIB old stock in case.
Honeywell ST799 keeps turning off
- Thread starter Bob2016
- Start date
I haven't tried it but the browning of the circuit board (which is unusually ?melamine not epoxy) may well be accompanied by a distinctive smell, so comparing the two by sniffing them might shed some light on it. Certainly any heat damage to the previous generation of material which was phenolic is very obvious.
Also given the scenario you describe you might as well swap the "new" one on arrival, as then (a) you will test it and (b) you should then have a working backup battery and (c) if the battery in your existing one is already dead it can't get any worse and you can replace it at leisure or get someone else to do it. Will PM you about this if I can.
Also given the scenario you describe you might as well swap the "new" one on arrival, as then (a) you will test it and (b) you should then have a working backup battery and (c) if the battery in your existing one is already dead it can't get any worse and you can replace it at leisure or get someone else to do it. Will PM you about this if I can.
Thanks, I will test it (when the winter is over!)
I will probably carry on using the trusty one in their until it goes completely then replace it with the used one in the first instance as a precaution. I understand that in addition to the programmers simply breaking down with age it can also be caused by an external problem e.g. a with a faulty pump or actuator valves so will see how the used one runs and if that breaks down quickly recheck any external sources before using the new one
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