Component ID

[TucsonDon]

I have a 120VAC/14VAC 70VA transformer for my pool light. On the sec is this component that is intermittently failing. I am trying to id it so that I can replace it instead of the transformer ($120). The only making on it is H9 and DABK

 

[Lightium]

It's probably a capacitor.

 

[Diver300]

To me it looks like a self-resetting fuse. If it is, there could be an overload causing the transformer to overheat.

I think that it is one of these:- https://www.mouser.co.uk/ProductDetail/Littelfuse/RHEF900-2?qs=F6FIpiMdEVZEUj%2BekpsPsQ==

The symbol shows that it's made by Littelfuse.

 

[TucsonDon]

It's probably a capacitor.

Thats what I thought but tested the Fluke meter.

 

[Lightium]

If it is a fuse, did you test for continuity?

 

[Nigel Goodwin]

I would imagine it's a thermal fuse - and probably not resettable, as it would be a poor 'safety feature' if it reset.

Presumably they fail because it's getting too hot - either poor design (so it runs too hot), or the transformer has failed (shorted turns, so over heated), or too much load on the transformer.

 

[TucsonDon]

Don't think it is a fuse as it will work intermittently. I can get it to work turn power off then back on and it will fail. Then I can get it to work again and not fail.

 

[Tony Stewart]

It is certainly a PTC thermal polyfuse p/n RHEF900 available at Digikey For <$2

But it seems to be working as expected on and off. What is uncertain is the ambient temperature and what loads have increased causing it to switch off. The critical uncertainty is your threshold temperature. If it is getting almost too hot to touch. It's your excessive load.

Define your loads please. The surge and power stored is causing your symptoms.


It is rated to hold 9A <=16V RHEF900 = H9 16V - High Temperature

 

[TucsonDon]

It is certainly a PTC thermal polyfuse p/n RHEF900 available at Digikey For <$2

But it seems to be working as expected on and off. What is uncertain is the ambient temperature and what loads have increased causing it to switch off. The critical uncertainty is your threshold temperature. If it is getting almost too hot to touch. It's your excessive load.

Define your loads please. The surge and power stored is causing your symptoms.


It is rated to hold 9A <=16V RHEF900 = H9 16V - High Temperature

That would make sense, I pulled it away from the windings while trying to troubleshot and has not failed but being in Az the ambient temp could be part of it. It is a couple of yrs old but just started, maybe getting weak. Not a lot of load as it is driving a pool led light.

At least I know what it is and have a part# Tony Stewart thanks!

 

[Tony Stewart]

I don't have a lot of details but if it is getting hot, a little 12V fan might make it happier, retrofit to maximize the air velocity across the surface.

On second thought, 120VAC/14VAC 70VA hmm probably makes 12V to 14Vdc for about 50W max. You might be able to see if your pool lights run on 12Vdc or a car battery. These supplies are cheap and almost free if you find an old PC power supply.

 

[TucsonDon]

I don't have a lot of details but if it is getting hot, a little 12V fan might make it happier, retrofit to maximize the air velocity across the surface.

On second thought, 120VAC/14VAC 70VA hmm probably makes 12V to 14Vdc for about 50W max. You might be able to see if your pool lights run on 12Vdc or a car battery. These supplies are cheap and almost free if you find an old PC power supply.

Tony Stewart there is no room for a fan. Worked all afternoon yesterday (ambient ~80°), turned it on for an hour then off for a bit then back on w/o fail.

This morning (ambient ~50°) I turned it on light came on for brief moment then turned off. Turned power off for a bit then back on and same thing happens.

Ordered replacement poly-switch from Digi-Key with part# Tony Stewart posted.

 

[Tony Stewart]

Tony Stewart there is no room for a fan. Worked all afternoon yesterday (ambient ~80°), turned it on for an hour then off for a bit then back on w/o fail.

This morning (ambient ~50°) I turned it on light came on for brief moment then turned off. Turned power off for a bit then back on and same thing happens.

Ordered replacement poly-switch from Digi-Key with part# Tony Stewart posted.

We still do not know exactly what lamps (link parts) nor the transformer temperature to properly analyze the cause.