Honeywell st9100 timer problems

[Plipplop]

Have Honeywell ST9100a I’ve had to replace the relay on a number of occasions, can anyone point me to a copy of the schematic circuit diagram I can download. Have been told it’s a capacitor that’s at fault but before I change that want to check the circuit. Any help would be appreciated

 

[Basher]

Hi Plipplop
It's clear from a few blogs and videos on the web that the blue 0.68uF type X capacitor that is used as a 'mains dropper' is a common source of one or more of the relays not pulling in. As the capacitor fades in value over time there is less voltage to drive the relay(s). I think you may need someone on the inside to help you with a circuit diagram of the internals though.
Best wishes repairing it - do use the correct X type capacitor!

 

[Plipplop]

Hi Plipplop
It's clear from a few blogs and videos on the web that the blue 0.68uF type X capacitor that is used as a 'mains dropper' is a common source of one or more of the relays not pulling in. As the capacitor fades in value over time there is less voltage to drive the relay(s). I think you may need someone on the inside to help you with a circuit diagram of the internals though.
Best wishes repairing it - do use the correct X type capacitor!

Brian,
thanks very much for your prompt reply, I may have to change the unit as it’s really needed by the family, it will give me a chance to change the cap without any pressure and hope it works. Once again thanks for your help

 

[Plipplop]

Brian,
thanks very much for your prompt reply, I may have to change the unit as it’s really needed by the family, it will give me a chance to change the cap without any pressure and hope it works. Once again thanks for your help

Brian,
just a quick update for you, I received the .68uf cap this afternoon changed it and it duly cured all problems, so as you stated this is the fix fir these types of problems. Prior to this I checked with multimeter and have the readings available, also checked the new cap as comparator as the original would appear ok to the ‘naked’, I think I might post the readings so others can check component before ordering and maybe getting it wrong. I bought it from farnell it’s 0.91 pence but 6 pounds postage, best to pick up from local radio spares store if possible.

 

[Basher]

Brian,
just a quick update for you, I received the .68uf cap this afternoon changed it and it duly cured all problems, so as you stated this is the fix fir these types of problems. Prior to this I checked with multimeter and have the readings available, also checked the new cap as comparator as the original would appear ok to the ‘naked’, I think I might post the readings so others can check component before ordering and maybe getting it wrong. I bought it from farnell it’s 0.91 pence but 6 pounds postage, best to pick up from local radio spares store if possible.

Hi Plipplop
Thank you very much for letting us know how it turned out, always nice to hear.
Farnell is great, except for the postage!
Glad it fixed the problem.
Best regards.

 

[Col at Rylands]

Interesting post.
Have holiday home in France and have had the same problem I.e. message to heater not getting through. I know with normal capacitors they visually bulge on top if duff. Can not see the same on the blue square ones.
91 pence seems better than £28.58 (cheapest I could find)
Will let you know if I have a good result.
Cheers Chaps
Col

 

[Malcolm]

Hi Plipplop
It's clear from a few blogs and videos on the web that the blue 0.68uF type X capacitor that is used as a 'mains dropper' is a common source of one or more of the relays not pulling in. As the capacitor fades in value over time there is less voltage to drive the relay(s). I think you may need someone on the inside to help you with a circuit diagram of the internals though.
Best wishes repairing it - do use the correct X type capacitor!

Yep. Replacing this capacitor fixed the problem on my Honeywell ST9100 controller. May thanks

 

[Lou]

(Just bumping a few older threads, they will drop off what is new soon)

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