AA Battery charger broken part

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  #1  
Old 10-12-20, 04:42 PM
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Red face AA Battery charger broken part

Hello,
Newbie here. The photo show the bottom of an old AA battery charger. You can see one part ( a resistor?) is broken while the other one is intact. Question is what is the broken part and where can I get a replacement? Thanx.


 
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  #2  
Old 10-12-20, 05:36 PM
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Is that a universal battery charger for any AA's or specific to one device ?
That looks like some type of glass diode.
It may have been used as a type of thermal fuse.

 
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Old 10-12-20, 05:56 PM
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The intact device on the left is a diode. I can not tell for sure if the busted device is the same thing.
 
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Old 10-13-20, 01:23 PM
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Universal. 2 AA batteries one one side and 2 on the other side.
 
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Old 10-13-20, 01:49 PM
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So this is a glass pin diode? It looks to be brown or orange with a black stripe in the middle. Any idea what I would order? Thanx
 
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Old 10-13-20, 02:42 PM
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Seeing that the old diode was riveted in place. Do you have a soldering iron to install a new one?
 
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Old 10-13-20, 03:35 PM
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If you look closely at the good one it will have some numbers on it. They will begin with 1N. All diodes are numbered 1Nxxxx
 
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Old 10-13-20, 08:25 PM
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That looks like a thermistor to me. Diodes will have a band on one side to indicate cathode.
Axial NTC thermistor has same glass packaging as a zener diode, but lacks band and often also lacks any printing.

Thermistor probably was used to control charging current depending on the temperature. Measure resistance of the good one and check if resistance changes depending on the temperature. If it does, it is a thermistor. Measure resistance at 25C (77F) to find value of the thermistor. Standard thermistors are 1k, 10k and 100k, but since it is used for charge control, yours might have lower or some non-standard value.
 
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Old 10-13-20, 08:35 PM
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Universal. 2 AA batteries one one side and 2 on the other side.
Replace it with a new charger.
It would be highly unlikely to identify the correct replacement part,
 
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Old 10-13-20, 08:46 PM
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I usually say keep the old things running but this is the one and only case I say get a new one. The new universal ones are good I have one that can charge NI-CD NI-MI and several different types of lithium chemistry batteries the slots are spring loaded and can accept several different lengths of cells.
 
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Old 10-14-20, 07:14 AM
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Yes just buy a new charger.

It does not matter what it is because finding a replacement will be a near impossible without a part number and you do not want to gamble.
Also the contact points look badly corroded so the other ends of them are also probably bad.
 
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Old 10-14-20, 09:32 AM
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Yes I have a soldering gun. Joyce
 
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Old 10-14-20, 02:43 PM
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Unfortunately, even with a good magnifying glass and turning up the good diode, I don't see a single letter or number .
 
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Old 10-14-20, 03:19 PM
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I don't see a single letter or number
As I wrote earlier, I am pretty sure that is NTC thermistor. Not a diode. Axial thermistors don't have any wiring on them.
Do you have a multimeter? Measure resistance across the good one. Measuring at 25C (77F) will give you the value you need.
 
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Old 10-16-20, 10:01 AM
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I measured at 72 degrees F and got 121.3 Ohms.
What does that tell me I need?
 
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Old 10-16-20, 10:44 AM
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Does the value change as temperature change?

121 ohms sounds way to low to be NTC. They are usually at kilo ohms range.
 
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Old 10-16-20, 07:26 PM
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Do these multimeter readings make sense?
Start at 120K @ 70 degrees.
Hair dryer air run with it pointed toward charger for 4 minutes
Reading after 4 min. 80K (Temp was probably 90 degrees in area of charger)
 
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Old 10-16-20, 10:15 PM
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Start at 120K @ 70 degrees.
Was the reading 120kOhms or 120ohms?
Earlier, you said 121 ohms.

If that was 120kohms, that probably is 100kohm NTC. Which is the one below.
https://www.mouser.com/ProductDetail...OqaQsLJQ%3D%3D

This NTC is around 124k ohms at 68F (20C)
Compare your readings to Rt for 100kohm in page 3 of following datasheet. (Temperatures are in celsius)
https://www.mouser.com/datasheet/2/4...00-1762699.pdf
 
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Old 10-17-20, 06:48 AM
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120K Ohms. My bad. That Mouser product is what I will order, in fact, it looks like the one that is in there. Thanks so much for your help. Joyce
 
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Old 10-17-20, 06:58 AM
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https://www.mouser.com/ProductDetail...NJy7JXkw%3D%3D

This one might work better since it has higher power rating.

 
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