question about Sencore Might Mite II TC-114 tube tester

[klamsoss]

Good afternoon all,

I'm restoring a Mighty Mite II Tube Tester (TC114 model). I have the user manual, which includes a schematic, and I've reviewed the TubeSound article on restoration of a Mighty Mite (it's a good guide, if anyone out there has one of these they are rehabbing). My question is about if it's more likely that my tube tester was assembled wrong, or the schematic and parts list in the reproduction manual is wrong.

R9 is listed and depicted as 120k ohm in the manual.
R10 is shown as 100k ohm in the schematic, and does not appear on the parts list.

My unit clearly has a 150k ohm R9 and an 82k ohm R10 based on the color bands (my DMM indicates 163k ohm, and 86k ohm respectively). Every other resistor matched the schematic exactly, so I'm not sure what's up. I also don't know enough about how tube testing circuits work to know what impact these values would have on the testing.

The attached pictures are the schematic and then the actual resistors in question. The bulb is the short indicator bulb. Strictly speaking, this arrangement doesn't match how the circuit is depicted in the manual, either! In addition to the resistors having different values, the bulb and R10 are swapped, relative to what the schematic indicates.

Can anyone shed any light on this? Can someone who owns a working TC114 check their unit for me and report back?

Many thanks!

 

[ChrisMarantz]

I would guess that like many manufacturers, Might Mite never updated their schematics to shows production changes that were made overtime. If the components looks original to the set, they are probably correct - Chris