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#1 2013-12-19 21:35:12

NO_H2O
New member
Registered: 2013-12-19
Posts: 1

VL 502 noise

I am new to this forum.
It has been a long time since I have done amp work.
I picked up a VL 502 a few tears back for my oldest son. Now years later I had to do the "heater harness" mod and try to put this amp back in service. The only equipment I still have is a variack, Fluke 77 and an old tube tester.
Heater harness mod finished, the amp had a low grade 60 cycle hum (not terrible, but you can hear it). It is not affected by changes in gain, tone, volume or channel change. I bought a full set of tubes (7 each 12AX7's and a pair of EL34's) and swapped them, set the bias and have no change in the noise. After going back in it a few times to double and triple check my work and swap some more tubes around, I decided to take it over to a friends place to try it in his studio to make sure it was not caused by the power in my work shop and to try different cables to make sure I was not chasing my tail.
It has been so long since I heard this amp working that I can't remember if it had this noise before.
Is the low hum normal with this hi gain amp or should I jump into cap replacement?
It has been a long time since I have had to do this type of work and I have not done much with printed board amps.
Any help would be great.
Thanks Dave.

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