13-02-2020, 06:59 PM
(This post was last modified: 13-02-2020, 06:59 PM by ppppenguin.)
Tried another 2 of them. The first of these had iffy C10 (it was getting warm) but was still working. Also needs cleanup round EHT as there are odd crackles. The other one had failed a smoke test and had blown its mains fuse. Shorted diode in bridge. Now works well.
The main series pass regulator gets very hot. Now i know why. I used a variac to determine that hum appeared at 193V mains. My mains is about 235V. Unless you have chronically low mains voltage that means a lot of heat in the regulator. The transformer doesn't have any alternative taps so for my own monitor I may fit a small buck transformer. I'll have a dig around my toroids. Even a tiny one will be enough. A 12+12 one will knock 24V off the mains which feels about right.
Just 1 more of these monitor lurking here. i may have a go at it tomorrow.
The main series pass regulator gets very hot. Now i know why. I used a variac to determine that hum appeared at 193V mains. My mains is about 235V. Unless you have chronically low mains voltage that means a lot of heat in the regulator. The transformer doesn't have any alternative taps so for my own monitor I may fit a small buck transformer. I'll have a dig around my toroids. Even a tiny one will be enough. A 12+12 one will knock 24V off the mains which feels about right.
Just 1 more of these monitor lurking here. i may have a go at it tomorrow.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
