IBM 5150 Trimmer Capacitor Suggestion

[alejack12001]

I am starting to rebuild an IBM 5150 machine. I have the 5150 motherboard, however, I have discovered that the trimer capacitor is damaged. According to minuszerodegreeqs website, the trimmer capacitor can be replaced by a 20pf capacitor. Minuszerodegrees doesn’t say whether the replacement capacitor is a ceramic or mica capacitor. I am inquiring of the membership who may have replaced this capacitor what type was used. The enclosed picture shows what minuszerodegreeqs suggested. The picture doesn’t show the plus/minus relationship. Can someone suggest the correct polarity for the connection or does it make a difference?

 

[modem7]

The picture doesn’t show the plus/minus relationship. Can someone suggest the correct polarity for the connection or does it make a difference?

The capacitor type used in this application will not have polarity.

Minuszerodegrees doesn’t say whether the replacement capacitor is a ceramic or mica capacitor.

Usually, in this situation, one refers to the data sheet of the chip, which in this case is an Intel 8284A.
Having a quick look (I'm on holiday), I cannot see the particular crystal-capacitor configuration used by IBM in the 5150.
So maybe someone else (preferably an electrical engineer) will comment.

 

[alejack12001]

The capacitor type used in this application will not have polarity.


Usually, in this situation, one refers to the data sheet of the chip, which in this case is an Intel 8284A.
Having a quick look (I'm on holiday), I cannot see the particular crystal-capacitor configuration used by IBM in the 5150.
So maybe someone else (preferably an electrical engineer) will comment.

So glad to read your replies. I have ordered 20pf mica capacitor. So, no need for further investigation. Enjoy your holiday.