Power adaptor

Gavin Robertson's picture

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Joined: Jan 25, 2019

Replies: 2
Power adaptor
January 25, 2019 - 10:28pm

What was going on here?   Purchased a 12v 10A power supply adaptor to replace one that had failed.   Required for a 12v desiccant dehumidifier drawing 5A.   The unbranded Chinese adaptor (intake of breath!) would cut out after an hour or so - very hot.   Replacement just the same.   Extra ventilation did not help.   Oddly, introducing an analogue multimeter set to measure amps solved the issue.   Got to thinking why.   Realised that meter had some simple electronics that might be dealing with currents.   I had a spare Drok voltage/current boost module to hand so tried introducing this - sure enough no overheating and no cutting out.   So I have amateur knowledge of electronics but am used to problems as of engineering background    Curious to know what do the knowledgeable people think is the design issue with the adaptor that causes the problem?   Did cost cutting or poor design play a part?   Why did introducing more circuitry cure the problem?

 

Aswinth Raj's picture

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Joined: Aug 16, 2016

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Must be because of cheap quality
January 28, 2019 - 1:56pm

Everythign makes sense except for this part

 Oddly, introducing an analogue multimeter set to measure amps solved the issue.

So what values did you read on the multimeter? Did you also consider the peak current that the dehumidifier might draw?

I am not sure if your adapter was really rated for 10A, the only way to find our is by connecting it to a load and monitor the current and heat of the adapter. 

The reason for cuttign off should be in-built temperature protection circuit. 

Gavin Robertson's picture

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Power adaptor
January 28, 2019 - 2:54pm

Thanks for reply.

Meter in output positive wire read continuous 5A on 10A dc range until adaptor cut out.   With Drok in output from adaptor the item does continue to run without the adaptor getting more than just warm so a convenient success.   Note I made an error in describing dehumidifier - should have described as thermoelectric Peltier type.

Aswinth Raj's picture

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cutts off even when u place the meter?
January 28, 2019 - 4:08pm

Meter in output positive wire read continuous 5A on 10A dc range until adaptor cut out.  

But you told you were not facing the cut off problem when the meter is connected.

If the problem occurs all the time, then it is mostly because you received an faulty adaptor. 

Gavin Robertson's picture

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Power adaptor
January 29, 2019 - 11:00pm

Sorry my error in last response.   With the meter in line the adaptor did not cut out.   That was the puzzle!