- 2024
- Jan
- 3
Mistakes were made - a long long time ago.
2024 brings this device from years ago, which I opened to find a mistake in assembly. This Bell & Howell IMD-202-2 NIXIE meter has a 10k resistor in the oscillator circuit, where the board and schematic specified a 15k.
The carbon resistor used was so sloppy that it didn’t really matter what went in there, of course, as long as it was close enough to the value specified. The part had long since drifted out of tolerance, the upper limit being 11k - this one read 11.64k!
I have to wonder if the person building this kit did that accidentally, or on purpose because they didn’t have the correct part, or maybe they chose it to correct something else. I’ll never know, but a 15k precision went in to the circuit and seems to be working without issue. I have to assume it was simply an honest mistake, as I didn’t see any evidence of rework on the bottom of the board.
Stay tuned for my findings on trying to fix some of this device’s drift.
