Hi Tom,
Don't worry about the humming noise. My 667 and 666 have always done that with 5U4's. Checking two 5U4GB's on the 666 just now, I get 100-105 for both sides on both tubes. Seems to me that I have had rectifiers which slightly pinned the meter, though. In any case, you might want to check the resistor values associated with the "S" switch. Those are R10,11,12,13,14.
Have always enjoyed using the 666/667. Even though I have a Hickok 752A, I still use the Eico's, too.
Steve L.
Don't worry about the humming noise. My 667 and 666 have always done that with 5U4's. Checking two 5U4GB's on the 666 just now, I get 100-105 for both sides on both tubes. Seems to me that I have had rectifiers which slightly pinned the meter, though. In any case, you might want to check the resistor values associated with the "S" switch. Those are R10,11,12,13,14.
Have always enjoyed using the 666/667. Even though I have a Hickok 752A, I still use the Eico's, too.
Steve L.
Hi Craig,
Not burnedfingers anymore. Tried to get my Burnedfingers name back but someone here decided they wanted my old name. Anyway getting back to the matter at hand. My Mercury lists switch position "C", Meter setting of 45 without tube in the socket, and socket #4 and socket #5. I tested a NOS 5U4 a few minutes ago and received readings of 64 and 65 on the two sections of the tube. I had no audible noises and had no meter banging.
Hope this is of some value.
Not burnedfingers anymore. Tried to get my Burnedfingers name back but someone here decided they wanted my old name. Anyway getting back to the matter at hand. My Mercury lists switch position "C", Meter setting of 45 without tube in the socket, and socket #4 and socket #5. I tested a NOS 5U4 a few minutes ago and received readings of 64 and 65 on the two sections of the tube. I had no audible noises and had no meter banging.
Hope this is of some value.
Just a Hunch
I have an Eico 666 too and it also buzzes when testing rectifiers (which I would say is normal on this model) but it doesn't peg the meter. Soon after I got my tester there was a problem with the Grid knob which, I believe, is a rheostat. This control is supposed to be set at 0 (zero) when testing rectifiers. Anyway, the old tech who was teaching me stuff at the time replaced it but couldn't find an exact replacement part so he put in a part with a switch which I click into the off position when testing rectifiers. Just a hunch, but you might try to make sure that when yours is set to 0 that it truly is. Perhaps some current is getting through the control and it's affecting the reading.
Or, I could be completely out in left field on this . . .
Charlie
I have an Eico 666 too and it also buzzes when testing rectifiers (which I would say is normal on this model) but it doesn't peg the meter. Soon after I got my tester there was a problem with the Grid knob which, I believe, is a rheostat. This control is supposed to be set at 0 (zero) when testing rectifiers. Anyway, the old tech who was teaching me stuff at the time replaced it but couldn't find an exact replacement part so he put in a part with a switch which I click into the off position when testing rectifiers. Just a hunch, but you might try to make sure that when yours is set to 0 that it truly is. Perhaps some current is getting through the control and it's affecting the reading.
Or, I could be completely out in left field on this . . .
Charlie
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