Tubes Asylum

Posted by FrankC (A) on December 05, 2014 at 20:29:25

OK, so I used my TV7-D/U and tested these 5AR4 and 6L6GC tubes that I bought on fleebay. Sellers were all reputable ones with over 5k feedback. Anyways, they tested good on my tester. The tester was recalibrated by Dan Nelson just a few years back.

Well, I got the idea over the Thanksgiving weekend to swap out the stock tubes in my ARC preamp and plugged these in. Well, I smelled heavy plastic burning smell, and when I unmute and mute the unit, I heard a big thump noise in my speakers. I then turned everything off, unplugged the preamp, waited 30 minutes, then swap the tubes. When I switched everything back on, the preamp went dead within a minute. It turned out that the fuse was burnt. Under the advisement from Nick Gowan, our local audiophile doctor, I've not turned it on and will be taking the preamp to him next week.

Nick indicated that the parameter of how these tubes are used in my preamp is different than what the TV7-D/U tests. So my question is how to best test these tubes to ensure that they can work in my preamp. Both were used as rectifier in the power supply section. Are there other testers that I should be using instead?

One of the local electronic supply place has one that indicates whether the tube is good or bad like a battery indicator. Just wondering if that it would be better to use that instead?

Thanks in advance,
FrankC