Re: Clean and Lubricate Pots in Tek 475


Simon
 

Some have had success dribbling IPA on the pot shafts with a hypodermic syringe and turning the shaft from stop to stop many times. It helps if the scope is positioned vertically to benefit from gravity.
For calibration you can look through the steps in the service manual, and work out how long that would take with the specified test instruments, then factor in a technician’s labor. It would probably work out more than the scope is worth. They can be picked up for about $250 on eBay and maybe twice that for a fully refurbished one. You can adjust the timebase fairly easily with a crystal controlled function generator, but the vertical amplifier calibration requires more sophisticated instrumentation. My function generator has a TTL output and I swapped the 74LSXX output IC for a 74HCXX and could measure a 5 ns rise time on 10 ns/div so I was happy with the frequency response, but I never got both Y amps the same. To calibrate them, page 75 of the service manual gives you the list of instruments required. It is rather daunting.
It seems a nice idea to restore it to its original factory state, but unless you plan to use it in your job it is probably not worth it.
Simon

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