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Author Topic: Cap went boom. Photocopier repair  (Read 148 times)

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I think this is the equivalent https://www.digikey.com/products/en?mpart=EKMQ401VSN271MQ40S&v=565 height might be an issue though. The QR code on the cap reveals nothing online. Is there anything else I should look at for equivalency? Thanks
   
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I think this is the equivalent https://www.digikey.com/products/en?mpart=EKMQ401VSN271MQ40S&v=565

Is that other large cap swollen?  You might need two

Also check your input rectifier and make sure the diode junctions are all good.  That cap shorting out could have taken some pn junctions out

Dave
   

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Thanks dave I was going to replace the other one as well. I might just replace the rectifier as well now. Thanks
   
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Thanks dave I was going to replace the other one as well. I might just replace the rectifier as well now. Thanks

Looks like there is also a fuse with through-hole leads coming off of you ac input (I think) you may want to check and possibly replace
   
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As for cap dimensions, just measure it and make sure you get the size constraints right as well as capacitance, voltage and footprint.  This might work as its smaller than your first link.
 https://www.digikey.com.au/product-detail/en/nichicon/LGL2G271MELA30/493-7504-ND/3884127
   
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Hi Jimboot,

Electrolytic capacitors are the weak point of electronics. I recently had to change three of them every few months in a satellite receiver that was only six years old. These capacitors in the power supplies withstand high currents, but for reasons of economy, engineers don't size them enough, so they heat up, and a capacitor that heats up degrades faster.
They can be replaced by any capacitor of the same capacity and voltage or higher voltage, but if possible bigger so that they don't have the same problem later on. The capacitors with "low ESR" are the best (lower serial resistance, but this information is not always available).
Then, it's all a question of space in the box to put them, sometimes you have to connect them with extra wires, it's not a problem if the wire section is sufficient (diameter > 1 mm is generally enough).
 


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"Open your mind, but not like a trash bin"
   

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F6,

You make a very good point.  When replacing failed Electrolytic Capacitors or
Tantalum Capacitors I select a replacement, space permitting, of at least 50%
more capacity
at a somewhat higher voltage rating.

I replace the Surface Mount Electrolytics with wired radial electrolytics by the same
philosophy.  Small is not better as I see things.


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The animal mind ALWAYS reacts to what it does not understand. This is what sets dogs barking. If you are going to tell the truth, you are going to have to be okay with barking dogs, because they will harry your passage until you pass through town.
Les Visible - 27 February 2020
   

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Hi Jimboot,

Electrolytic capacitors are the weak point of electronics. I recently had to change three of them every few months in a satellite receiver that was only six years old. These capacitors in the power supplies withstand high currents, but for reasons of economy, engineers don't size them enough, so they heat up, and a capacitor that heats up degrades faster.
They can be replaced by any capacitor of the same capacity and voltage or higher voltage, but if possible bigger so that they don't have the same problem later on. The capacitors with "low ESR" are the best (lower serial resistance, but this information is not always available).
Then, it's all a question of space in the box to put them, sometimes you have to connect them with extra wires, it's not a problem if the wire section is sufficient (diameter > 1 mm is generally enough).
Thanks F6 I've learned something.
   

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Switching supply caps typically suffer this on the output stage. Those look to be input stage.  400v? 220 in? Should be ok.  In your case the caps are probably of poor quality.

For just a bit more, Id go with the rubycon caps  https://www.digikey.com/product-detail/en/rubycon/400MXK270MEFCSN25X30/1189-2655-ND/5023839

Mags
   
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.  Small is not better as I see things.

I agree.  Size constraints are the dictator but I would go with the largest size and lowest ESR for heat dissipation purposes if possible.
   
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