?? composition resistors actually have more spurious reactance than film resistors. I have no idea why these were used but suspect carbon or metal film resistors would work at least as well.

On 5/7/2024 5:36 PM, Jared Cabot via groups.io wrote:

I recently performed a few repairs on a friends 3457A multimeter (new RAM battery, replacement current range switching relays and added thermal insulation on the LM339 vreg) and have also just acquired one of my own that I'll do the RAM battery replacement, LM339 thermal insulation and maybe power supply capacitor replacement on.

I noticed there are a number of 51K carbon composition resistors in the signal path, which I found a bit strange...
You can see them in the input switching section highlighted in yellow of the linked image below, R101, R102, R201, R202, R203, R204


As carbon composition resistors are prone to drift and noise with age, would it be of any benefit to replace these with metal film resistors? Or is there some reason carbon composite were used here (high pulse energy handling and low inductance etc)?



Thanks!
Jared