I broke my 747 Tube Tester!

[Wil_Bloodworth]

Well, after replacing all the capacitors and calibrating the machine, I went back to the beginning of the calibration... just to check again. When I got to step #2, the Test 1 button no longer worked. It doesn't seem to do anything at all now. It won't calibrate and it's as if the button no longer works at all. So, my new-old tube tester is now a door stop.

I also notice that the two 5W resistors on the board with all the calibration pots are overly hot as well.



Any thoughts on how to figure out what I could've broken?

Thank you,

- Wil

[pelud]

Try cleaning the contacts for the light bulbs. They are notorious for going bad. 

You can also get low readings when they get dirty.

Edit: Also check that the "signal" wire is not shorted to ground.