Author Topic: Tektronix 468 Position and Beam Find Problem  (Read 1775 times)

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Offline cliffordjsmith

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Tektronix 468 Position and Beam Find Problem
« on: December 29, 2015, 12:05:22 am »
My Tektronix 468 Position adjustment knobs don't move either trace below the center of the display, and the Beam Find isn't visible even when I push it after I have a trace displayed. I've got the service manuals, but would appreciate any advice, especially on whether I should start with the power supply or the vertical preamplifier board.
 

Online tautech

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Re: Tektronix 468 Position and Beam Find Problem
« Reply #1 on: December 29, 2015, 12:18:28 am »
My Tektronix 468 Position adjustment knobs don't move either trace below the center of the display, and the Beam Find isn't visible even when I push it after I have a trace displayed. I've got the service manuals, but would appreciate any advice, especially on whether I should start with the power supply or the vertical preamplifier board.
Welcome to the forum.

Always start with PSU checks.
If all seems well it could be an imbalance in the vertical system.
In the Repair board you'll find a good pdf for troubleshooting Tek scopes:
https://www.eevblog.com/forum/repair/repair-documents-and-links-sticky-me-please-mods/


Check the schematic for DC voltage values, these help immensely in finding an area in the circuitry that is faulty. Study the Service manual for instruction as to how the scope should be set for DC voltages to be relevant.
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Offline Addicted2AnalogTek

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Re: Tektronix 468 Position and Beam Find Problem
« Reply #2 on: January 01, 2016, 06:22:45 pm »
If you're 468 has socketed transistors, your best bet is going to be to pull the vertical amp board and check all the semiconductors on it.   It sounds like there is a major offset in the voltages between the vertical deflection plates.

It would help if you put some signals into the inputs and gathered some more info.  Dig into the Volume 1 manual and run the vertical section performance check, subbing equipment as you need to.    If frequency isn't stated, such as for the amplitude calibrator equipment checks, the frequency is 1Khz.
 


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