Bias -V pin 5 jtm60

Chummlyo · 10-19-2008, 10:52 AM

Hi all need some help I run a jtm60 and am gigging around spain i have changed the power tubes and put in EL34 Svetlana winged C and need to run a quick check for the Bias, nearest Tech is 4 hours away I have been told you can check from pin 5 power tubes with a fluke to give you a ball park, the amp sounds ok and the tubes look Normal when powered up but would like to know .I can get my amp checked properly back in UK as going back soon . any help would be much appreciated .

mikeboone · 10-19-2008, 01:35 PM

I would think that if your amp sounds normal you will be OK. You can only check the bias voltage at pin 5, not the current. Current is what needs to be checked.

There are online merchants that sell bias checking devices. This link is to a popular seller of amp supplies.

https://taweber.powweb.com/biasrite/br_page.htm

10-19-2008, 10:52 AM	#1
Chummlyo Junior Member Join Date: Jun 2008 Posts: 1	Bias -V pin 5 jtm60 Hi all need some help I run a jtm60 and am gigging around spain i have changed the power tubes and put in EL34 Svetlana winged C and need to run a quick check for the Bias, nearest Tech is 4 hours away I have been told you can check from pin 5 power tubes with a fluke to give you a ball park, the amp sounds ok and the tubes look Normal when powered up but would like to know .I can get my amp checked properly back in UK as going back soon . any help would be much appreciated .

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10-19-2008, 01:35 PM	#2
mikeboone Senior Member Join Date: Nov 2007 Location: Houma, LA Posts: 169	I would think that if your amp sounds normal you will be OK. You can only check the bias voltage at pin 5, not the current. Current is what needs to be checked. There are online merchants that sell bias checking devices. This link is to a popular seller of amp supplies. https://taweber.powweb.com/biasrite/br_page.htm

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