An EICO 249 VTVM, Part 3: Cleaning the range switch.
Friday, April 10, 2026 at 08:30:39
As the carbon film resistors on the range switch decided to go way out of tolerance as they were being worked with, I removed them all and decided to dump the switch assembly in the ultrasonic bath.
Watching the dirt lift off was quite fascinating…it just drifted away.
It’s not the easiest to see because the dark wafers don’t show much difference, but they feel different now. The ceramic wafer at the bottom is also much whiter, and some of the green growing on a previous owner’s mod is gone.
Once the new resistors are installed, I’ll give the rings a shot of cleaner-lube, and put some dielectric grease on the detents.
Next part of this series: Coming soon.
Previous part of this series: https://wereboar.com … d-resistors-therein/
Wrapup and final thoughts: