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Old 08-28-2013, 10:22 PM
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bigaudioal bigaudioal is offline
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Test-O-Matic Model L-18 tube tester questions

Picked up this tube tester, cheap on eBay to mess with. It was showing a short light on every tube I put in, even ones I know are good from my other tube tester. So time to inspect. Going to replace the 1 cap in it. Looks a little melted. 0.033 mfd 400v. Tested all the resistors and found two way out of whack. A 100K ohm and a 270K ohm. Not surprising these resistors both lead to the short light that kept coming on. My question is what watt should these resistors be? I cannot find a manual or schematic for this tester anywhere showing what wattage the resistors are. Anyone have any idea or suggest a wattage that would be safe? 1/2 watt? 1 watt?

Here is a picture of the tester.

Thanks.
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Last edited by bigaudioal; 04-28-2014 at 08:50 PM.
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Old 08-29-2013, 06:50 AM
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earlyfilm earlyfilm is offline
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Quote:
Originally Posted by bigaudioal View Post
tube tester . . . . . was showing a short light on every tube I put in, even ones I know are good . . . . My question is what watt should these resistors be?
Most tube testers use a neon bulb, capacitor and one or more resistors to make the shorts tester. When the capacitor leaks, the resistors overheat.

Since the cost between a 1/4 watt and a 1 watt is so small, I'd put one watt resistors in and be done with it.

The extra wattage will not hurt.

James
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Old 08-29-2013, 09:01 AM
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bigaudioal bigaudioal is offline
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Quote:
Originally Posted by earlyfilm View Post
Most tube testers use a neon bulb, capacitor and one or more resistors to make the shorts tester. When the capacitor leaks, the resistors overheat.

Since the cost between a 1/4 watt and a 1 watt is so small, I'd put one watt resistors in and be done with it.

The extra wattage will not hurt.

James
Thanks James. 1 watts are the easiest to find in these values anyway. Appreciate your input.
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