I recently bought an old 1960's Tektronixs oscilloscope at a yard sale. I had to replace an obviously burnt and cracked vacuum tube, but I am still unable to display a trace while on "normal" mode. The trace will only show on the right third of the screen. I am wondering if there is still a dead component somewhere or if it's just operator error.
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Re: Malfunctioning 60's Tektronixs Oscilloscope??
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Re: Malfunctioning 60's Tektronixs Oscilloscope??
I presume you've tried adjusting the horizontal position control. Also, it's best to test using "Auto" triggering instead of "Normal", if your scope has that. Normal triggering requires that a signal be present on the vertical input to trigger a trace. Auto mode will trigger a trace even in the absence of a signal.
Tube circuits are just a couple years ahead of my time, so I can't give much advice on trouble-shooting. Another great place to look for that expertise is the TekScopes Yahoo Group. You have to sign up and all that, but the people that really know these vintage scopes hang out there.Comment
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Re: Malfunctioning 60's Tektronixs Oscilloscope??
Sorry, I guess a little clarification is needed. Triggering mode is set to auto, triggering slope is set to internal +. Horizontal display is set for "normal". Even with the horizontal position set all the way left, the trace only appears on the right third of the crt. Signal input or not, I still can't center the trace.
Thanks for the tips, gentlemen.Comment
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Re: Malfunctioning 60's Tektronixs Oscilloscope??
Understood, auto/normal usually refers to the trigger mode, but Tektronix does tend to put "normal" on a number of different switch positions. Anyway it sounds like some abnormal DC offset in the horizontal amp. Good chance it's an electrolytic cap, given the age of the unit.
If you intend to troubleshoot, first step is to obtain the service manual. It should have a schematic with nominal voltage measurements.Comment
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Re: Malfunctioning 60's Tektronixs Oscilloscope??
I have managed to find a pdf of my manual. However, I'm totally green when it comes to electronics. I wouldn't even know where to start. But I must say that I've gotten more help here than from Tektronixs themselves. So, thanks all around.Comment
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Re: Malfunctioning 60's Tektronixs Oscilloscope??
After a good visual inspection, the place to start troubleshooting something is usually to verify the power supply outputs. The service manual should indicate the allowable tolerances.
But I can't recommend poking around a live CRO chassis for a beginner. Study the schematic and locate the test points with the power off. This may be an interesting learning experience in and of itself. Be aware that capacitors can retain enough charge to be dangerous even with the power off. Use alligator clip leads to set up measurements with a multimeter, then turn the power on.Comment
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Re: Malfunctioning 60's Tektronixs Oscilloscope??
Thanks for the useful info, but being as much a beginer as I am, I'm going to leave that to a buddy of mine who knows more than me by a long shot. The best part is the good advice I got here.Comment
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