Tektronix 422 Repair/HV Troubleshooting

“Totally unexpected find” is the excuse for this one. I was shopping for tubes and saw this one in the aisle next to the tubes, covered in mud.

Anyways, the second excuse for acquiring one more oscilloscope is – it is small, cute, and tiny, Comparison with Tek 211 here.


The entire exercise is documented here in a video.


Some of the items/pics explained in the video are here.

1. Power supply unit – can not be turned on by itself due to an AC interlock in the indicator unit. You can bypass it by directly plugging power to the transformer



2. HV oscillator – Oscillator/Driver in power supply and HV transformer / rest of the circuitry to drive the CRT is inside the indicator unit.


3. Two types of VR Tubes are in use, in addition to Zeners.

a) In HV regulation GV4S- 1400, for 1400 V reference. This is a ruggedized HV regulator tube.


b) In the indicator unit regulator, ZZ1000, 81 V reference.





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