Hello I was wondering what size light bulb to get for the initial check to see if anythings shorted. I remember someone talking about putting a 25 or 40 watt bulb inbetween the variac and the radios cord....if it glows dimmly then........no obvious shorts, but if it glows brightly then uh oh shorts....just cant remember where this article is

I would go with a 25W lamp.

But, the dim-lamp test is usually used when you don't have a variac. But, using the lamp with a variac initially would be OK. However, you'll need to turn up the variac most of the way to get the bulb to light, even if there is a short.

:I see. so if the 25w lamp is lighting full intensity then there is a short (obvesiously) would this still possably damage a radio or reduce damaging current enough to just light the light bulb, you unplug the radio and come to the conclusion that thers a short, more work involved and heres your sign,........lol
:I would go with a 25W lamp.
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:But, the dim-lamp test is usually used when you don't have a variac. But, using the lamp with a variac initially would be OK. However, you'll need to turn up the variac most of the way to get the bulb to light, even if there is a short.

If you use a bulb to power up a radio, you're supposed to start with a really low wattage bulb nowhere near the radio's wattage (say 15 or 25 watts). Then you increase it slowly and watch the radio. I think you're supposed to go over the radio's wattage by a bit in order to get it to operate at almost full voltage. The low wattage bulb shouldn't glow too brightly, but may glow at half or 3/4 brightness, depending on radio wattage. As you increase wattage, it should be dim. If it still is bright, or if all bulbs are near full brightness, then you definitely have a short. If you use a 15 or 25 watt bulb on a 90 watt radio, though, and just stay with this wattage, you aren't going to get the radio to do much, and the bulb may glow quite brightly (know what I'm saying?).

Thomas

Personally I think that it is poor practice to use a bulb to find trouble in the radio. I believe that you should first check condensers and possibly resistors. Look for obvious wiring troubles. Perhaps test tubes (at least test for bad filaments or duds). Perhaps test the power transformer for unusually low primary resistance. Then, after all faulty components which can be found with a meter are replaced, power up the radio with a bulb and go from there. If you power up the radio with a bulb without replacing condensers, though, a shorted condenser may blow a transformer even at half voltage.

Thomas

:yes, thats the answer I was looking for. so the light bulb test has flaws,..because I know transformers are the last thing I want to blow, especially an I.
f transformer

:Personally I think that it is poor practice to use a bulb to find trouble in the radio. I believe that you should first check condensers and possibly resistors. Look for obvious wiring troubles. Perhaps test tubes (at least test for bad filaments or duds). Perhaps test the power transformer for unusually low primary resistance. Then, after all faulty components which can be found with a meter are replaced, power up the radio with a bulb and go from there. If you power up the radio with a bulb without replacing condensers, though, a shorted condenser may blow a transformer even at half voltage.
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:Thomas