Telequipment D75 oscilloscope repair part 2: Success!

Here's how I fixed a Telequipment D75 oscilloscope. I had to replace the HV diodes, the inrush limit thermistor of the HV PSU and one output transistor from the bright up board (blanking amplifier). It also had some minor issues with the horizontal amplifier, which were caused by dirty trimmer pots.

The unobtainium TO203 transistor was replaced with an NTE159.
The HV diodes were replaced with Diotec DD600 diodes.
The Mullard VA1040 thermistor was replaced with EPCOS B57236S0121M051.

00:00 Intro
00:21 Removing the HV multiplier
00:58 Testing the HV multiplier
03:12 Desk lamp EMC
03:44 HV multiplier safety
04:13 Testing the CRT
04:50 More HV multiplier tests
08:12 More HV PSU troubleshooting
09:11 First signs of life!
10:04 No trace troubleshooting
14:02 No G1 bias experiment
14:39 No trace root cause
16:27 We finally have a trace
17:19 Adjusting CRT bias
20:43 More HV PSU troubleshooting
22:40 More blanking amplifier troubleshooting
27:26 More HV PSU troubleshooting
28:08 Re-installing the HV multiplier
31:21 Horizontal issues
31:59 Horizontal troubleshooting
33:55 Outro

Manuals and schematic: https://w140.com/tekwiki/wiki/Telequi...