|
There are some precautions re: variac:
1. is that in a set w/tube rectifier, you have to have a fair amount of input voltage to light up the rectifier so you can get any DC out at all...by that time, the DC output is likely to be high. To re-form the electrolytics, it is probably better to use a 0-400 volt dc supply connected to the electrolytics, with the rectifier tube removed, and TV set unplugged, bringing the voltage slowly up to the recommended b+ voltage of the set...watching the current meter for excessive current draw.
2. is that if you operate the set at a reduced B+ voltage on a variac, you can overload the flyback/horizontal output tube by not providing it with enough drive signal to produce proper bias.
What I do is to use a series light bulb if I suspect a short in a set...use about a 100 watt lightbulb in series with the power cord. If the bulb instantly glows bright, there is a short...if it goes bright initally and then dims, it is most likely O.K. to go ahead and just plug it in. If the set doesn't have one, install a fuse in the powerline to help protect it.
|