Replacing capacitors : is it safe to do this ?

bob412

Active Member
I'm in the process of recapping the power supply board on a Fisher 201 receiver . The required capacitor values are 25v 100uf . I only have 25v 220uf . Would I blow something up if I used the higher uf rated capacitor or should I order the correct values . Thanks
 
No but seriously - I wouldnt see any issues with what you propose - however this depends on how many caps there are to replace.

You always want to maintain or exceed the voltage rating - and you can generally safely exceed the uF rating.

If you upgrade the value of power supply caps you also need to consider that the power-on surge will increase, and this will put extra strain on your rectifier bridge & power switch contacts. Keep that in mind if you do this. Any powerswitch issues could take a long time to manifest, but an underrated rectifier could pop at any time without warning.
 
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No but seriously - I wouldnt see any issues with what you propose - however this depends on how many caps there are to replace.

You always want to maintain or exceed the voltage rating - and you can generally safely exceed the uF rating.

If you upgrade the value of power supply caps you also need to consider that the power-on surge will increase, and this will put extra strain on your rectifier bridge & power switch contacts. Keep that in mind if you do this.


This particular power supply board has a total of three capacitors . There are two 50v 47uf capacitors and one 25v 100uf capacitor . Well , I guess I'll order some more capacitors . Don't want to screw anything up on this one .
 
i always replace like for like uf or closest to it and maybe up the voltage . it worked just fine all those years as is . plus next person to look inside wont be wondering why the ratings have been changed .
 
Don't forget the 2200uF at C3. That's the power supply's reservoir and first smoothing cap.

From the service manual at hifiengine.com

Fisher 201 receiver power supply diagram.png Fisher 201 receiver power supply.png
 
to be fair, its not audio so upping the capacitance aint gonna hurt it, but I would replace the 2 transistors with newer/meatier the 984 can see a ksc2383 and the 1061 is made today, but ksd526 number.
 
100uF in power supply terms is a small (some may say tiny ) capacitor. It's power up surge current is trivial, so doubling the value will have no bad effect .
 
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