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Help to identify a component

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ShawnR

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I am working on a battery charger for a friend. The out put transitor and fuse were blown. It still does not work so digging further, I found this component attached to the heatsink of a schottky diode. I think it must be a thermal fuse but wondering how to get a value? On the circuit board, it is labeled as RT1. It is about the size of a 1n914 diode. It tests open. Any input for me? Thermal fuse? It was clamped onto the heatsink near the TO220 case schottky
 

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Tony Stewart

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The glass diode is used to sense temperature. It should behave like any small signal diode on Ohmmeter bias. replace with 1n914 in correct polarity or equiv.
Diodes are the disposable thermometers used in hospitals.

Often the diode forward voltage is used to force the bias on a power transistor , so that when T rises Vf drops and bias is reduced.
 

ShawnR

Member
Thanks Tony. I figured it was a thermal fuse, and showing open, shorted it to try it. The circuit lead to the u controller so I figure it was only a signal. The unit then powered up with an error so it is normally open I guess. There is no band or markings to indicate polarity so I don't think it is a diode. Regardless, the battery charger is in such rough shape it is not worth any more time. Lots of signs of water damage on circuit board and a fair amount of smt components that I am not set up to work with. I recall something about what you said but would not have come up with that possibility. Thanks. I am on to other projects
 

Tony Stewart

Well-Known Member
Most Helpful Member
It was hard to tell. Try a macro setting with a webcam or better camera

If exposed to water damage. Use a bottle of isopropyl alcohal and brush any dust off and rinse, then dry for 1hr or more minimum with a cold blower. Use safety measures.
 
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