Re: Pease help diagnosing my 2235


lagunablue94c
 

Thank you all for the suggestions.
I think I'm a little in over my head here, nevertheless it is a fascinating exercise and a great learning experience.
Based on what you guys have said, I'm making some assumptions:
  1. There is a ripple in the CRT PS.  This would explain the superimposed 60Hz AC signal when measuring an audio signal.  What I don't understand is why the same thing is not happening when the internal reference signal is measured.
  2. There are some resistors or diodes out of spec in the Z-axis circuitry
  3. The DC Restorer circuitry is not working properly.  Kevin, I'm trying to find reference to the blanking pulse during retrace--Is this excerpt from pg. 3-17 it?
  • "Fast-rise and fast-fall transitions of the Z-axis output signal are coupled to the crt control grid through C855 to start the crt writing-beam current toward the new intensity level.  The Dc Restorer output level then follows the Z-axis output voltage level to set new bias voltage for the crt control grid."
Reading this stuff is really making my head smoke!
So here's my dilemma: The manual lists a bunch of equipment needed to make adjustments, none of which I can really afford.  My entire test-bench consists of a Fluke 77 DMM and a broken Tektronix 2235.

Based on the above assumptions I've ordered a Fluke 80k-6 probe to check the CRT voltages and now I'm planning to get an ESR meter to check the caps in and around the PS. 

Is there any other piece of equipment I absolutely need to have to make this diagnosis?

Thanks again,
Bryan

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