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Vintage Capacitor Replacement

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computeruser

New Member
Hello again. circa 1966 Farfisa organ amplifier. Power supply caps (and others) leaking and for sure shot. Strangely all the caps are even values I.E. 500 / 50 / 200/ etc. Guess what? MCM and others only list the values I remember (from Heathkit days) like 470 / 47. Do I really have to tack on little baby adder cap's (4.7 / 33) to make up this difference? I am aware of the voltage requirements. I have also check the good ole web on this subject - most sites say do do de-rate values - but come on - 10%????
 

zevon8

New Member
Electrolytic capacitors have pretty wide tolerance ranges, something like +/-20% are very common. I would not worry about the small difference. Be sure to cover the voltage range needed, and also be sure to check for non-polarized caps also.
 

mneary

New Member
10% still leaves the capacitance at a conservative value. The present caps have probably lost most of their capacitance anyway, and any new caps will sound better.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
zevon8 said:
Electrolytic capacitors have pretty wide tolerance ranges, something like +/-20% are very common.
I would suggest +/-20% would be pretty rare, the tolerance is usually MUCH worse than that on electrolytics +100%/-50% isn't uncommon. So it's in no way critical, it's obvious what replaces what:

500=470
200=220
120=100

etc.
 

ericgibbs

Well-Known Member
Most Helpful Member
Hi,
In the good old days,around the 1960's, capacitors were rated in decade values. [pardon the pun].

ie: 50/100/500 uF,,, as stated the nearest uF will be fine.
 

zevon8

New Member
Nigel Goodwin said:
I would suggest +/-20% would be pretty rare, the tolerance is usually MUCH worse than that on electrolytics +100%/-50% isn't uncommon. So it's in no way critical, it's obvious what replaces what:

500=470
200=220
120=100

etc.

True, the +20 & -80 is very common. Depends on what you want to spend, and what the WVDC rating is. Filter caps should always be over spec'd anyways, more is better, you can never get "too smooth" or "too quiet", LOL.
 

computeruser

New Member
Great advice; thank you! I also noticed another quirk in the project - the old caps had two volt ratings. For example 12/18; 30/45; 50/65; 70/80. These numbers follow the designations VL and VI; VL being the lower number. Your opinion on what would be the correct number to shoot for. All the off-the-shelf cap voltages at MCM supply are 16/25/50/100/250.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Go for the higher voltage, I would also STRONGLY suggest you use 105 degree capacitors, rather than the cheaper 85 degree ones - I only stock 105 degree ones now at work.
 

computeruser

New Member
Thanks to all of you who so kindly replied, and this fantastic online service, I am ready to fix this baby up for my friend. Wish me luck
 
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