Yet another 'replacing carbon resistors with metal film' question....

Jared Cabot

Hi all,

I have a PG502 TM500 module here I'm poking away at, and although the capacitors all test better than the datasheets in all respects (Those Vishay 30D caps are pretty good!), some of the old brown square ended carbon composite resistors have predictably drifted.
I also found also that the 15V trimpot is high resistance unless you press on the dial leading to no voltage rails, so that will be replaced.

I want to replace all of the fixed carbon composite with new resistors, but I'm not sure which way to go...
I have a set of modern 5% carbon film resistors, and also a set of 50ppm 1% metal film resistors too. I'm not too worried about using film resistors on the power supply etc, but the rest of the circuit is what I'm not sure about. I assume in this situation, the metal film is better than the carbon film seeing as they are both spiral cut?

What's the rule of thumb here? Should I just shotgun the metal film resistors and hope for the best, or use carbon composition resistors instead?

Here's the data sheets of the resistors I have:

Carbon film:
Metal film:

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