Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: 6v6Pin1 on September 19, 2015, 02:33:07 pm
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I have a new JJ 5y3 that lowers B+ about 25 volts compared to a normal JJ 5y3. Is this an interesting tube to have around, or is it just a matter of time before it self destructs and takes out other components? Would you use it or throw it out?
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I would use it and not think twice.
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I would use it and not think twice.
Agree.
New manufacture 5Y3's are known to have given a higher B+ than NOS 5Y3's.
Maybe they fixed it? If you have a NOS 5Y3 pop it in and see what B+ it gives, is it close to your new JJ 5Y3?
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The charts on this data sheet will tell you what the expected voltage drop is for a given current draw:
http://www.mif.pg.gda.pl/homepages/frank/sheets/093/5/5Y3GT.pdf (http://www.mif.pg.gda.pl/homepages/frank/sheets/093/5/5Y3GT.pdf)
It would be interesting to know whether your the new or old 5Y3's behave like the old American ones.
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If you have an oscilloscope, look at the ripple waveform on the first filter cap and make sure it's "even looking." I had a new Chinese 5AR4/GZ34 which produced a lower than normal B+ compared to another GZ34 of the same brand. It turned out that one of the two diode sections in the tube was weak, and it produced asymmetrical ripple. If both sections of the tube match OK, I agree with the others that it's probably fine, but I'd avoid one with a significant mismatch.