toneman2121 Posted July 3, 2014 Share Posted July 3, 2014 can i measure voltage in a tube amp with the speakers disconnected? power tubes removed? one tube in the right output is glowing almost as bright as a light bulb. it's a stereo amp so i believe i can compare left and right and come to some conclusion. there is a resistor that looks a bit like it was overheating but measures correct resistance, i thinking when it's on, it breaks down...possible? the amp still works for a minute then the tube starts glowing and then the amp makes random popping/crackling sounds. in the attachment, the tube that;s glowing is v7 in the output section page 1. the resistor is r116 on page3. thanks for looking, frank www.gibson.com_Files_schematics_GA30RVS.pdf Quote Link to comment Share on other sites More sharing options...
Brazzy Posted July 3, 2014 Share Posted July 3, 2014 I know from experience that a resistor or even a fuse can look and measure good but be bad when it heats up. 1 Quote Link to comment Share on other sites More sharing options...
toneman2121 Posted July 4, 2014 Author Share Posted July 4, 2014 thanks, you guys, for responding. i'll try replacing that resistor, brazzy. and thanks for the warning, hurghanico. ;) Quote Link to comment Share on other sites More sharing options...
toneman2121 Posted August 18, 2014 Author Share Posted August 18, 2014 well as usual i lollipop up. all this time i've been going back to the amp every now and then. checking lollipop. of course the first thing i did was swap tubes from one position to another...same lollipop. finally decided to bring it to a well recommended tech. jim walton's his name. in the philly area. google him. hell, i thought, one more search on google, a few more checks. swap some tubes and if still no luck i'll call him today. turns out when i swapped tubes the first time i put the exact same lollipop tube back in the exact same lollipop socket. off to get a set. Quote Link to comment Share on other sites More sharing options...
Brazzy Posted August 18, 2014 Share Posted August 18, 2014 well as usual i lollipop up. all this time i've been going back to the amp every now and then. checking lollipop. of course the first thing i did was swap tubes from one position to another...same lollipop. finally decided to bring it to a well recommended tech. jim walton's his name. in the philly area. google him. hell, i thought, one more search on google, a few more checks. swap some tubes and if still no luck i'll call him today. turns out when i swapped tubes the first time i put the exact same lollipop tube back in the exact same lollipop socket. off to get a set. Hate when the lollipop falls in the dirt, lol. I just replaced the tubes in my DT50 the original tubes got to the point where they would work for 10-20 minutes and then just stop glowing. My first experience with bad tubes. I guess they would heat up and something inside would lose connection shutting the heaters off. Then I would let them cool down for a long while and they would repeat that cycle for a while before they just quit all together. 1 Quote Link to comment Share on other sites More sharing options...
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