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Old 03-22-2022, 01:29 PM
Jon1967us Jon1967us is offline
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Join Date: Nov 2018
Posts: 350
No HV, boost on CTC-22

Having trouble kick starting this thing. Any advice would be appreciated.

Symptom: No high voltage measured and Boosted B+ is too low.

Quick Reference Pics:





Full Schematic: https://drive.google.com/file/d/1Ar9...ew?usp=sharing

Info and Measurements:

• No HV measured
• 280 and 285 B+ rails measure correct
• Voltages on H Osc measure correct
•#Damper diode was bad replaced with NOS
• Waveform on pin 2 of V11 H out looks good, is at correct amplitude. Haven't measured frequency yet, but on the scope it appears to be a little low.
•#Voltage at pin V11, pin 2 appears a little low, at -40 (should be -51)
• Other voltages on V11 appear a little too high - pin 7 =144v, pin 8 = 52v
• Cathode current is very low at 30mA
• Boost voltage only 210v (should be 500)
•#Voltage at H Out anode cap is 140
• Adjustment of H Hold or waveform doesn't improve cathode current or HV
• The Fly is buried deep in the box and I currently can't access for testing for shorts or ringing tests
• H out and HV rect tubes tested and subbed with known and tested NOS ones

I'm wondering if the following caps may have something to do with lack of boost. C80 (.0018 @ 1KV boost), 82 (100pF @ 5KV). What other tests can be done to help to trace to my faulty component?
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