Rascal Super Resistor

[sophiecentaur]

The unit must be about 12? years old.

Backup battery in the control box was dead (end of its natural life).

I wasn't aware until a recent total mains failure and the Bell box siren wouldn't stop running.

I bought a new 1.2 Ah battery then I noticed a burned out resistor on the control board.

I want to replace it but can't see its value. It's mounted vertically and is just to the right of the processor (on the diagram in the manual it is labeled "Option 1". It's no use trying to reset the unit until that's been sorted.

Has anyone an idea of its probably value? It must be fairly low to have roasted so dramatically with 12V max on it.

It would also be useful to replace the Bell box battery (5 cells in a blue sleeve with PCB mounting solder terminals). Maplin didn't have any of that style.

[Guest anguscanplay]

The unit must be about 12? years old.

Backup battery in the control box was dead (end of its natural life).

I wasn't aware until a recent total mains failure and the Bell box siren wouldn't stop running.

I bought a new 1.2 Ah battery then I noticed a burned out resistor on the control board.

I want to replace it but can't see its value. It's mounted vertically and is just to the right of the processor (on the diagram in the manual it is labeled "Option 1". It's no use trying to reset the unit until that's been sorted.

Has anyone an idea of its probably value? It must be fairly low to have roasted so dramatically with 12V max on it.

It would also be useful to replace the Bell box battery (5 cells in a blue sleeve with PCB mounting solder terminals). Maplin didn't have any of that style.

that battery is too small if you bought a direct replacment there is the reason for the blown component

i really do not like the idea of replacing components unless you are a qualified electric component replacer i have never done it in twenty years for the cost of a new panel it isnt worth it

[morph]

The unit must be about 12? years old.

Backup battery in the control box was dead (end of its natural life).

I wasn't aware until a recent total mains failure and the Bell box siren wouldn't stop running.

I bought a new 1.2 Ah battery then I noticed a burned out resistor on the control board.

I want to replace it but can't see its value. It's mounted vertically and is just to the right of the processor (on the diagram in the manual it is labeled "Option 1". It's no use trying to reset the unit until that's been sorted.

Has anyone an idea of its probably value? It must be fairly low to have roasted so dramatically with 12V max on it.

It would also be useful to replace the Bell box battery (5 cells in a blue sleeve with PCB mounting solder terminals). Maplin didn't have any of that style.

The best advice here is to get an engineer in. If because of a bad repair your house burns down, you will most likely not be covered. Probably not the advice you want but in the circumstances it is good.

[Guest anguscanplay]

The unit must be about 12? years old.

Backup battery in the control box was dead (end of its natural life).

I wasn't aware until a recent total mains failure and the Bell box siren wouldn't stop running.

I bought a new 1.2 Ah battery then I noticed a burned out resistor on the control board.

I want to replace it but can't see its value. It's mounted vertically and is just to the right of the processor (on the diagram in the manual it is labeled "Option 1". It's no use trying to reset the unit until that's been sorted.

Has anyone an idea of its probably value? It must be fairly low to have roasted so dramatically with 12V max on it.

It would also be useful to replace the Bell box battery (5 cells in a blue sleeve with PCB mounting solder terminals). Maplin didn't have any of that style.

unless thats the part guard silent set cut to enable resistor in which case you dont have a problem

see why you need an engineer its just not worth it

and that battery is still to small

[sophiecentaur]

I have a lot of experience with circuit fault finding and repair of lots of devices. Haven't burned down a house yet - but I take your point about safety awareness.

Actually, internal fuses are there to look after that sort of problem - they eliminate the possibility of a lot of power dissipation in an appliance.

The battery replacement I used was exactly the same as the original - nothing else will fit into the space, actually.

I don 't understand how a 'too small battery' could possibly burn out a resistor although a totally knackered battery which presented a short circuit might take a lot of current from the charging circuit and burn out a small value series resistor. They are tiny components and fry with less than 1Watt.

I suppose a peak of current due to a thunderstorm could be to blame - but just one component? I would have expected a lot more to be damaged under those circumstances.

The bell box battery is original - 5 nicad cells in a blue sleeve. There used to be a lot of that sort around at one time but not any more.

[Guest anguscanplay]

I have a lot of experience with circuit fault finding and repair of lots of devices. Haven't burned down a house yet - but I take your point about safety awareness.

Actually, internal fuses are there to look after that sort of problem - they eliminate the possibility of a lot of power dissipation in an appliance.

The battery replacement I used was exactly the same as the original - nothing else will fit into the space, actually.

I don 't understand how a 'too small battery' could possibly burn out a resistor although a totally knackered battery which presented a short circuit might take a lot of current from the charging circuit and burn out a small value series resistor. They are tiny components and fry with less than 1Watt.

I suppose a peak of current due to a thunderstorm could be to blame - but just one component? I would have expected a lot more to be damaged under those circumstances.

The bell box battery is original - 5 nicad cells in a blue sleeve. There used to be a lot of that sort around at one time but not any more.

actually fuses are there to protect curcuits not components several well known panels will burn out components rather than fry the whole system they are there for exactly that reason optimas,gardtec 370 to name just two /

a 2.1 amp battery will fit and should be the smallest size used

you posted that the resistor is labelled option 1 that sounds like the resistor we used to cut to get instant night set ( thats why its labeled with option rather than just a id number)

you answered yourself with the point about the knackered battery

as i have said i have never changed components in over twenty years it just isnt worth it but if i felt i had the ability i wouldnt have been asking how to tell the value of that component

nothing personal i always get rilled when people asking for advise start sentences with the word " actually"

[arfur mo]

The unit must be about 12? years old.

Backup battery in the control box was dead (end of its natural life).

I wasn't aware until a recent total mains failure and the Bell box siren wouldn't stop running.

I bought a new 1.2 Ah battery then I noticed a burned out resistor on the control board.

I want to replace it but can't see its value. It's mounted vertically and is just to the right of the processor (on the diagram in the manual it is labeled "Option 1". It's no use trying to reset the unit until that's been sorted.

Has anyone an idea of its probably value? It must be fairly low to have roasted so dramatically with 12V max on it.

It would also be useful to replace the Bell box battery (5 cells in a blue sleeve with PCB mounting solder terminals). Maplin didn't have any of that style.

hi sophiecentaur,

i don't know this panel, but many panel makers installed a large bodied curent limiting resisitor to reduce the current pulled needed to recharge if the battery if it was flattened during a prolonged powercut. this resistor was cut if a dry cell battery was used and may be 'option 1' in its instructions but i don't know for sure.

what happens though is the battery becomes faulty and draws more current than originally designed for, so smokes or burns out the resistor due to heat disipitated.

from your post you seem have enough general electyronic expertise, so you should be able to trace from the battery terminals through the pcb to see if i'm right. if i am, i'd suggest to remove the resistor and replace with a fuse, and swap out the batery every 2 years for what they cost.

as to battery size and suitability, with your system in good order, place you meter on milliamps and in series with the standby battery. then turn off the mains from the spur and read the quesient current drawn. ideally this would be done with the system fully armed but not always practickle.

it is then a simple matter to calculate by dividing the result into 2.1 to see how long a good well charged battery should safely last. we'd aim for 8 hours plus on your system, newer ones last a lot longer due to bigger batteries now installed.

regs

alan

[Guest anguscanplay]

hi sophiecentaur,

i don't know this panel, but many panel makers installed a large bodied curent limiting resisitor to reduce the current pulled needed to recharge if the battery if it was flattened during a prolonged powercut. this resistor was cut if a dry cell battery was used and may be 'option 1' in its instructions but i don't know for sure.

regs

alan

not on this panel option one is either part set instant set or part set reduced volume

[magpye]

From the Manual >>

Note : To reduce the volume of the speakers cut the resistor (option 1) shown on the PCB drawing.

[arfur mo]

not on this panel option one is either part set instant set or part set reduced volume

Hi Angus,

thanks for info, i wonder as it alters the volume if the wrong speaker or to many speakers have been installed? might have been a short on the speaker cable.

mind you at 12 years old it has done a very good turn and owe's nothing, so me thinks time for a shinny new panel and siren would be my recomendation, especially with the noise pollution laws in force since this was fitted and the 5k possible fines.

regs

alan