Tek 465B HV Oscillator Riding on Vertical Signal
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Tek 465B HV Oscillator Riding on Vertical Signal
Latest Project. 465B/DM44 with intermittent HV oscillator riding on Vertical. Not as bad as the camera shows but you can see the HV oscillator riding on the vertical. Of course it's intermittent. When not present trace is sharp. I suspect a bad tant somewhere in the PSU decoupling network and I'll have to do some quick troubleshooting when the defect occurs. More to follow.
An old gray beard with an attitude. I don't bite.....sometimes 
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Re: Tek 465B HV Oscillator Riding on Vertical Signal
By fiddling around with the trigger controls I was able to determine that the HV oscillator riding on the vertical is always present which should make troubleshooting easier.
Checked all the PSU voltages first. They are clean, right down to a 2mV/div limit on a 2430. Especially the +15V supply which feeds the HV oscillator. So it's getting into the vertical circuits via another method, either directly or inductively. So the next step is probing the vertical pre-amp and output.
Checked all the PSU voltages first. They are clean, right down to a 2mV/div limit on a 2430. Especially the +15V supply which feeds the HV oscillator. So it's getting into the vertical circuits via another method, either directly or inductively. So the next step is probing the vertical pre-amp and output.
An old gray beard with an attitude. I don't bite.....sometimes
Re: Tek 465B HV Oscillator Riding on Vertical Signal
It appears this time it isn't a tant. But the jury is still out. This 465B had extensive work by me. All the tants on the vertical board were changed as well as some on the main board and trigger/horizontal board. The PSU was re-capped. Channel 2 attentuator assembly changed and calibrated. And some other minor work.
An old gray beard with an attitude. I don't bite.....sometimes
Re: Tek 465B HV Oscillator Riding on Vertical Signal
As luck would have it the fault has disappeared. No amount of fiddle farting with the controls could persuade it to rear it's ugly head. It's not really a critical fault anyway and when it does appear it shows for perhaps 1 to 2 minutes and then disappears. So I guess I'll consider it "fixed" for now. But since the cover was off it did give me the opportunity to clean the attenuator decks which were slightly noisy.
Next project is a "solid" fault but may be a little challenging to track down. Stay tuned.
Next project is a "solid" fault but may be a little challenging to track down. Stay tuned.
An old gray beard with an attitude. I don't bite.....sometimes
Re: Tek 465B HV Oscillator Riding on Vertical Signal
It's only stopped doing it because you gave it some attention. I reckon it'll be broken the moment it goes back in the cupboard.
Re: Tek 465B HV Oscillator Riding on Vertical Signal
Sounds like you are an experienced senior engineer.
Re: Tek 465B HV Oscillator Riding on Vertical Signal
Nahhh... that's simple "Law of Irony" there. 
mnem
Murphy's a bitch. And she has puppies.
mnem
Murphy's a bitch. And she has puppies.