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Heathkit TC-1 Tube Tester Restoration Part 8


Heathkit TC-1 Tube Tester Restoration Part 8

Part 8: Initial Testing

The moment of truth has arrived.  Will it thrive, or go up in smoke??

I plugged the newly reassembled TC-1 into my variac to bring up the voltage slowly.  Before powering on the unit, I put the controls in the following positions:

  • Set Line: Full CCW
  • Filament Voltage: 0.75v
  • Lever switches: All in center position
  • Type: 1
  • Plate: 0 %

Then, I turned on the tube checker.  As I raised the voltage, there were no signs of obvious electrical problems, and the Line Voltage indicator slowly crept up.

I found that I could center the Line Level on the meter at any voltage between 107 and 130 vac line voltage.

I checked various filament voltages.  With the Line Level centered in the meter, I found that they were all around 10% higher that what was marked.  This is not too far off from the state it had arrived in, where filament voltages were high at that time, too.  But I figure that if some higher power tubes are tested, they may cause the voltage to drop a bit, so I can live with that.


Line Level Test OK

I went to to test a couple of tubes I had in my junk box.  A 12AU7, 12AX7 and 6AU6 all tested good in all sections, and there were no short or open elements found.  Many of the tubes that I had in my junkbox are not listed on the roll chart.  I’ll go through the procedure for testing those in a future post.

I need to find a knob for the Set Line control and 3 of the lever switches (6, if I want them to all match).  While I look for those, I’ll start refinishing the cabinet.


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