I bought a Triplett 2413 tube tester as a back-up and it will power up and gives readings.... but won't center up for the line check - at maximum on the pot, it will move up but stays to the left of center. I think the problem is R7... a 75K ohm resistor which now reads out at 115K ohms (schematic here: http://www.audiophool.cjb.net/Misc/tt2413..pdf). The parts list describes it as 1W resistor - however, it is a painted glass tube with leads and labelled "Triplett 75K" and doesn't look like the other (standard) resistors nor like any of the wire-wound ones. Any ideas what this might be? Will a standard 75K ohm work in its stead?

:I bought a Triplett 2413 tube tester as a back-up and it will power up and gives readings.... but won't center up for the line check - at maximum on the pot, it will move up but stays to the left of center. I think the problem is R7... a 75K ohm resistor which now reads out at 115K ohms (schematic here: http://www.audiophool.cjb.net/Misc/tt2413..pdf). The parts list describes it as 1W resistor - however, it is a painted glass tube with leads and labelled "Triplett 75K" and doesn't look like the other (standard) resistors nor like any of the wire-wound ones. Any ideas what this might be? Will a standard 75K ohm work in its stead?

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R-7 will cause the described problem if it is out of value. It could be a "dog bone" resistor which looks like your description, you can use standard resistors but you may need to parallel or put them in series to get the correct value.

Dave

:R-7 will cause the described problem if it is out of value. It could be a "dog bone" resistor which looks like your description, you can use standard resistors but you may need to parallel or put them in series to get the correct value.
:
:Dave

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It's definitely not a dog bone - it's painted glass - and where the paint is chipped off, it looks like it is filled with a white paste material. Just wonder why it is constructed this way - when none of the others are.....

Hi William,
Its different construction is probably from the manufacturer having them specially made. 75K 1 watt is an odd value, both then and now.
I agree with Easyrider8. Replace with a new 75K, and be prepared to parallel.
Try two CMF150HFCT-ND from Digi-key in parallel.

Best Regards,

Bill Grimm

:Hi William,
: Its different construction is probably from the manufacturer having them specially made. 75K 1 watt is an odd value, both then and now.
: I agree with Easyrider8. Replace with a new 75K, and be prepared to parallel.
: Try two CMF150HFCT-ND from Digi-key in parallel.
:
:Best Regards,
:
:Bill Grimm

Opps! CMF150KHFCT-ND.

:Opps! CMF150KHFCT-ND.

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Thanks Bill... I've gone through and found 3 other resistors way out of tolerance too... It shouldn't be too difficult a fix though