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Fusible resistor identification

Wurzel

Sep 2, 2011
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Hi
Trying to check the value of what I think are fusible resistors on the input side of a pcb mounted 230Vac (0-115,0-115 in series) transformer. Each winding is rated at 0.06A. The resistor has for bands which are: brown, black, brown, silver. Colours may have changed due to transformer failure.
Is there a calculation to help verify its value.
Any help gratefully received
 

duke37

Jan 9, 2011
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This may be a resistor, check with a meter for resistance.
Brown 1
Black zero
Brown 1 (Number of zeros)
Silver +/- 10%

So this could be a 100 ohm resistor. If a thermal fuse, 100deg C or perhaps a 100mA fuse.
A picture would help.
 

shrtrnd

Jan 15, 2010
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... or maybe info on the manufacturer of your board. Some manufacturers like specific
designs for their power supplies that we'd recognize by model or mfgr.
Right now we'd be doing a guessing game.
 

Wurzel

Sep 2, 2011
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Thanks for the feed back.
Sorry I don't have a picture at this time. I will look to post. Unfortunately there is no board info.
There is a device in each leg of the feed to the transformer. Both are open circuit after transformer failure.
Subject to posting a picture. The resistor looking device is slightly dark sky blue and about the size of a 2W metal film resistor. To be a fusible resistor. Would there be more coloured bands? For example five.
What purpose would resistor serve in the feed to a transformer? Some sort of ac choke maybe
 

shrtrnd

Jan 15, 2010
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It SOUNDS like a simple flameproof resistor. NTE has a wide variety of them.
The purpose of the resistor is to limit the current.
I would imagine there is a fuse elsewhere for your transformer input.
(Look for it. If it's there, your device is probably not a fuseable link).
If you can't find a fuse, I'm wrong, and maybe your device is acting as a fuse of some type.
 

Wurzel

Sep 2, 2011
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Many thanks for that. Yes there is a fuse protecting the transformer.
I think you are right about it being it a resistor. It possibly looks more like a metal film rather than a metal oxide. At 0.06A, 100R-2W would seem about right.
 

shrtrnd

Jan 15, 2010
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You can identify flameproof resistors, by the vent holes they have on the ends where
the axial leads attach to the resistor.
 

Wurzel

Sep 2, 2011
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Sep 2, 2011
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Thanks. I have checked and there does not appear to be any. I think I'll use a metal oxide film resistor at 2W. I think this will be suitable given the 0.06A transformer primary current.
 
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