1-177 tube tester problem

[miniman82]

I recently got one of these old military testers, but there seems to be something wrong with it. The bulb marked ‘fuse’ which is actually a type 81 lamp glows very brightly when I try to turn it on, and the line adjust rheostat gets hot. I assumed the power transformer was shorted so I put an AC current meter in place of the bulb and used a variac instead. I got over an amp of current draw which seems excessive, but the rectifiers did start to light up so I’m not sure.

Could it just have a shorted turn inside the transformer?

[dieseljeep]

Originally Posted by miniman82

I recently got one of these old military testers, but there seems to be something wrong with it. The bulb marked ‘fuse’ which is actually a type 81 lamp glows very brightly when I try to turn it on, and the line adjust rheostat gets hot. I assumed the power transformer was shorted so I put an AC current meter in place of the bulb and used a variac instead. I got over an amp of current draw which seems excessive, but the rectifiers did start to light up so I’m not sure.

Could it just have a shorted turn inside the transformer?

Does it act the same when the rectifier tubes are removed?

[miniman82]

Yes, I removed the tubes and same story. I guess it would be helpful to know what these are supposed to draw current wise from the wall, anyone have one that could check for me? The manual doesn’t have any figures.

[dieseljeep]

Originally Posted by miniman82

Yes, I removed the tubes and same story. I guess it would be helpful to know what these are supposed to draw current wise from the wall, anyone have one that could check for me? The manual doesn’t have any figures.

The fuse lamp only lites a little bit, when testing a tube with a large heater current, such as a 5U4. Also when first turning on, due to inrush current.

[miniman82]

I know, I have 2 other testers with similar lamps and they will glow dimly with a tube in them. This one lights up the room with nothing, hence my question.