Aleph power supply cap brand

[MikeZ]

I was considering the purchase of Nippon/Chemi-con capacitors for use in the power supply of Aleph 2. Does anyone have any experience with that brand? Thanks Mike

[Nelson Pass]

Those are fine. We currently use Cornell, and have used
Mallory in the past. For PC mounted snap-ins, usually its
Matsushita (Panasonic).

It's my understanding that regardless of brand, there's only
a couple of big companies that manufacture the materials.

[MikeZ]

Thanks so much for the reply! Mike

[moe29]

I used the big Nippon/Chemi-cons in my Aleph 2 (68,000uF) and they are fine.

[kilowattski]

If purchasing capacitors off of someplace like ebay one must be careful to note the age of the capacitor. Electrolytic capacitors have a definite shelf life.

[jacco vermeulen]

Originally posted by kilowattski
If purchasing capacitors off of someplace like ebay one must be careful to note the age of the capacitor. Electrolytic capacitors have a definite shelf life.

Maybe i may add a line
Even when buying new from a shop the capacitor may have been on the shelf for some time.
In either case, it does not harm to regenerate the cap by loading it very slowly, with a resistor in series, till say half of its operating voltage and slowly unloading it a couple of times.
Dried out caps get firm again this way.

[MikeZ]

I dont have alot of electrical expertise, however I did manage to get my alephs running. I am trying to improve some of it now. Can you explain how to cycle the caps and perhaps provide specifics like what voltage to use and what value resistors to use.

Wont simply installing them and using them cycle them and refresh them?

[highbias]

"Electrolytic capacitors have a definite shelf life."

They have a VERRRRRRYYYYY long shelf life(decades in fact!) and almost always need to be reformed before use. The actual working life span is much shorter than the shelf life is by a very wide margin. I have restored televisions fomr the mid 40's that have most of the original can FP multi section caps still working along just fine and the secret to getting them to last is simply to reform them if they've been sitting unused for more than a couple of years. To tell the age of a capacitor liik at the code date thats printed on the can, its normally printed on near the value or manufacturers info.

Applying full voltage to any electrolytic new or old is quite dangerous. Here is a link to a site on how to reform electrolytic caps safely... so they don't blow up in your face!

http://www.vcomp.co.uk/tech_tips/ref...eform_caps.htm
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I have the Chem-Cons in my 2's now for about two years and have had no problem with them... There seems to be a rash of surplus Chem-Cons on the market in the last year or so. All I can say is to take advantage of them while they're hot !

In my mini I have one 120,000 mfd Panasonic snap in per rail that I have secured with a DIY clamp system and hard wired in that have also been working great. Not a smidgen of hum out of the Mini.....

Mark

[jacco vermeulen]

Very nice link , Mark (HB)

If X is measured at constant intervals it is easy to make a graph of the unloading of the capacitor.
Drawn on graph paper by counting the squares the capacity of the C can be determined without the need for special equipment.
Getting an estimate on its capacity will give an estimate on its remaining life expectancy.

[highbias]

Well, I'd have to say that I follow you but at the same time I don't.......

I don't see how age will effect the actual capacitance of a given Capacitor. I have caps in old televisions that I have reformed that are almost 55 years old and if you measure the capacitance with a meter its pretty close to what the value is stated at on the label. The last set I fully restored (RCA 721TS) is still running fine almost 3 years later. I just restored an RCA 630 chassis circa 1946 that did have one can that would not re-form properly so I had to replace that one... but the new cap I installed is easily 30 years old. I reformed the replacement cap before installing it in the chassis and its fine. In the photo you can (unfortunately) tell which can is the replacement. Its label is old but obvious standing right in the center of the chassis, the old caps are under the black cardboard covers in front of the power transformer, in front of the high voltage compartment and under the chassis. All other coupling caps in all other circuits, including many micas are all new.

Mark