square capacitors with dots

[wiseguy]

has anyone found these type of caps to be bad?

[Steve McVoy]

They aren't mica. Probably paper in a plastic shell. I routinely replace them, since many are bad.

[ChuckA]

Terry,

For the color code on caps, take a look at this page:

http://www.pmel.org/HandBook/HBpage26.htm


Chuck

[wiseguy]

thanks guys,i guess i have never seen this type of "paper" capacitor,i always thought maybe they were mica and are suppose to be "high reliability"

[Lefty]

As described in the above link for determining value, they are of the mica type:

MOLDED MICA CAPACITORS: This was once a very popular type, rectangular with dots and arrow or similar directional indicator. Standard color code applies.

[Rob]

Terry,

I restored a Magnavox 1947 radio/record player console and while re-capping left these alone as I thought they were mica and were more or less bulletproof. They were exactly the same type caps as you pictured above. A while after returning this radio to almost daily use (I really like it) there was a smoke episode. One of thes caps literally split open letting the smoke out. It was one of a pair, each connected from opposite sides of the AC line to the chassis.

Rob

PS: Come to think about it, both of 'em shorted and split from the fault current. Where they were, one going short would have caused a hot chassis but not smoke.

[Eric H]

The caps with "Micamold" written on them are junk!

Philco used a lot of them in their TV's and they are always leaky or dead shorted.

Eric

[wiseguy]

well,this is interesting,i have been replacing them in this porthole chassis with orange drop type .05@600v.. hope it is safe!
terry
BTW I posted a pic (in swap area)of things that who ever wants them can have but pay for shipping,of the items are a couple of speakers,the one 10" one is good also but from a 1949 console that i can't remmeber the brand,also one of those odd shape preditca speakers.