Problem with short Test

Duardillo · 23rd February 2010, 10:42 PM

Hello everyone.

I have one accurate 151 tube tester, and im not sure if the "short test" works properly

When i test a valve ( even a new valve), a very smooth light shines on the indicator on most of the switch positions, but the light shines fully only when the selector is in the position marked as " disregard indicator lightning" in the manual . In some positions no light.

Is my tester broken? All my tubes must be discarded? When i do a test quality after, all have a "GOOD".

Thanks for helping and sorry for my english

Kind Regards

HollowState · 24th February 2010, 03:09 AM

This tester is an old timer. I don't think all your tubes are bad. I do think your tester may need some maintenance. If the short light glows dimly on a "known to be good" tube, you are probably seeing leakage. This can be caused by faulty calibration due to age from resistors or adjustments that have changed. It can also be caused by contaminates like moisture (humidity) and dirt getting inside on the switches and sockets. Most testers are set to a one megohm threshold for leakage indications. Consult your manual for calibration procedures. Perhaps remove the tester from the case and examine the inside for signs of contamination and clean as necessary.

Tom Bavis · 24th February 2010, 01:12 PM

Many emission testers have a capacitor in the leakage test circuit that will cause false "short" readings if it's leaky. And if that capacitor is original, there's a very good chance it's leaky.

Duardillo · 24th February 2010, 02:19 PM

thanks for the quick response, I remain your advice.

Kind Regards

23rd February 2010, 10:42 PM	#1
Duardillo diyAudio Member Join Date: Feb 2010	Problem with short Test Hello everyone. I have one accurate 151 tube tester, and im not sure if the "short test" works properly When i test a valve ( even a new valve), a very smooth light shines on the indicator on most of the switch positions, but the light shines fully only when the selector is in the position marked as " disregard indicator lightning" in the manual . In some positions no light. Is my tester broken? All my tubes must be discarded? When i do a test quality after, all have a "GOOD". Thanks for helping and sorry for my english Kind Regards

24th February 2010, 03:09 AM	#2
HollowState diyAudio Member Join Date: Aug 2006 Location: Taxland, New Jersey	This tester is an old timer. I don't think all your tubes are bad. I do think your tester may need some maintenance. If the short light glows dimly on a "known to be good" tube, you are probably seeing leakage. This can be caused by faulty calibration due to age from resistors or adjustments that have changed. It can also be caused by contaminates like moisture (humidity) and dirt getting inside on the switches and sockets. Most testers are set to a one megohm threshold for leakage indications. Consult your manual for calibration procedures. Perhaps remove the tester from the case and examine the inside for signs of contamination and clean as necessary. __________________ "The supercomputer is technologically impossible. It would take all of the water that flows over Niagara Falls to cool the heat generated by the number of vacuum tubes required." ~ Professor of Electrical Engineering, New York University

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Why doesn't it short? Or am I missing something?	wwenze	Construction Tips	7	23rd January 2010 03:26 AM
Square waveform test/simulate problem	mclarenpingu	Solid State	3	2nd February 2008 04:08 PM
Is there any test cd to test jitter using a scope ?	gaetan8888	Digital Source	4	10th August 2007 09:24 AM
How short can a TL be..?	Ian J	Multi-Way	10	31st March 2003 01:03 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read

24th February 2010, 01:12 PM	#3
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	Many emission testers have a capacitor in the leakage test circuit that will cause false "short" readings if it's leaky. And if that capacitor is original, there's a very good chance it's leaky.

24th February 2010, 02:19 PM	#4
Duardillo diyAudio Member Join Date: Feb 2010	thanks for the quick response, I remain your advice. Kind Regards

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)