My Mistral Oil boiler uses a Monoflame Minor 1 kero pressurejet burner with a Danfoss BHO11.1 control which is now obsolete. Recently while re-arranging some programmer connections and changing a very worn/dirty main power switch I think I have "spiked" the control box or photocell.
The mod I was working on is complete and checks out so is not the problem. The boiler starts correctly and fires almost immediately but goes on lockout at 7 seconds - after about 45 seconds I can reset the lockout and it will do the same again.
I suspected the photocell because that is supposed to come on at 7 seconds. but the 057H2020 is no longer available. I got a 057H7079 which is one of the ones listed for the later BHO70 series control box but with that fitted it fails in the same way.
When I put a multimeter on my photocell - the original 057H2020 - it reads about 89kohms under a bright light and around 2Mohms in the dark - is this about right or too high?
I am not sure that it is the photocell but as I believe my only other course of action is to get a conversion kit to the later BHO70.10 controller using an 057H7224 conversion kit - which is in total gonna cost around £100+ - is there a simple way to bypass the photocell temporarily to check if the control box is OK - in which case I can carry on scouring the net for a replacement for the old obsolete photocell.
Does anyone know what the difference between early and later photocells is?
I found a datasheet on the later Control box which says:-
" The photo current is measured with a direct
current ammeter in series with the photo unit (+
pole on terminal 12. Max. 5 kΩ internal resistance
in measuring instrument). With flame, photo current
must be at least 65 μA at 230 V.
With no flame, the measured photo current must
be max. 5 μA at 230 V."
- howeve if my multimeter is right and it is mains voltage on the photocell my old one at 89Kohms plus the meter's 5Kohm would only pass 2.4mA - the later one measures about 1.7Kohm which could pass around 34mA with another 5Kohms in series - much nearer what the datasheet suggests.
Any help gratefully received
dfoss
When you get to my age every day is a new experience
The mod I was working on is complete and checks out so is not the problem. The boiler starts correctly and fires almost immediately but goes on lockout at 7 seconds - after about 45 seconds I can reset the lockout and it will do the same again.
I suspected the photocell because that is supposed to come on at 7 seconds. but the 057H2020 is no longer available. I got a 057H7079 which is one of the ones listed for the later BHO70 series control box but with that fitted it fails in the same way.
When I put a multimeter on my photocell - the original 057H2020 - it reads about 89kohms under a bright light and around 2Mohms in the dark - is this about right or too high?
I am not sure that it is the photocell but as I believe my only other course of action is to get a conversion kit to the later BHO70.10 controller using an 057H7224 conversion kit - which is in total gonna cost around £100+ - is there a simple way to bypass the photocell temporarily to check if the control box is OK - in which case I can carry on scouring the net for a replacement for the old obsolete photocell.
Does anyone know what the difference between early and later photocells is?
I found a datasheet on the later Control box which says:-
" The photo current is measured with a direct
current ammeter in series with the photo unit (+
pole on terminal 12. Max. 5 kΩ internal resistance
in measuring instrument). With flame, photo current
must be at least 65 μA at 230 V.
With no flame, the measured photo current must
be max. 5 μA at 230 V."
- howeve if my multimeter is right and it is mains voltage on the photocell my old one at 89Kohms plus the meter's 5Kohm would only pass 2.4mA - the later one measures about 1.7Kohm which could pass around 34mA with another 5Kohms in series - much nearer what the datasheet suggests.
Any help gratefully received
dfoss
When you get to my age every day is a new experience