I have a vintage Tektronix Oscilloscope that I purchased in 1982. I was trying to use it on a project that I was working on, and found that although I was able to calibrate a 10X probe on channel 2, no adjustment of the probe (that worked on channel 2) really changed the appearance on the scope to look like a square wave.

I tried many local and non-local electronics repair operations, and found none that could fix it for me. In the mean time, I had purchased a "new" oscilloscope that was faster and relatively cheap.

I would still like, for mainly sentimental reasons, to get my old Tektronix in working order. I have attached a portion of a schematic from the service manual.

If anyone is willing to help me, I can provide other schematic jpegs and videos of the oscilloscope screen (I couldn't attach the videos to this post).

 

I had a couple old Iwatsu oscilloscopes that had similar issues. A small amount of Deoxit in all the switches did wonders for both scopes.

 

Thanks! I'll try it and let you know.

 

It is not clear to me what is the problem.
You have a Tektronix 2213 oscilloscope. It works on CHAN1 and CHAN2.
You have a 10X probe.
Has the probe been properly adjusted on CHAN1 and CHAN2?

 

In what way is the waveform on channel 2 incorrect?
Does it change depending on the attenuator setting?

 

This should be the manual for your scope.

The manual contains schematics of both vertical input channels. What exactly are you tweaking? I also suggest, as was mentioned, giving the input switching a bath.

Ron

 

I have a vintage Tektronix Oscilloscope that I purchased in 1982. I was trying to use it on a project that I was working on, and found that although I was able to calibrate a 10X probe on channel 2, no adjustment of the probe (that worked on channel 2) really changed the appearance on the scope to look like a square wave.

I tried many local and non-local electronics repair operations, and found none that could fix it for me. In the mean time, I had purchased a "new" oscilloscope that was faster and relatively cheap.

I would still like, for mainly sentimental reasons, to get my old Tektronix in working order. I have attached a portion of a schematic from the service manual.

If anyone is willing to help me, I can provide other schematic jpegs and videos of the oscilloscope screen (I couldn't attach the videos to this post).

A picture's worth a thousand words...

 

I have a spray can of DeoxIT that I've attached. Is this the stuff you are talking about?

I have seen more comments that don't think that using DeoxIT will work. It's a simple enough thing to try, so I will.

I'm wondering how I can calibrate the probe to show a nice looking square wave on channel 2, but have no adjustment on channel 1. Did you just spray every switch?

 

What does the trace look like with 10X probe on CHAN 1?
What does the trace look like with 10X probe on CHAN 2?

The adjustment is in the 10X probe. Have you adjusted this?

 

Hello,

The following page tells you more about the probe compensation:
https://www.teledynelecroy.com/doc/10x-passive-probes-appnote

Bertus

 

As I said the trace on channel l 2 was calibrated to show a nice square wave The same probe on channel 1 would not calibrate. I could not attach video files to this forum, so I can only say that it would not calibrate to anything close to a square wave. I am willing to email the video file to anyone that wants it.

 

As I said the trace on channel l 2 was calibrated to show a nice square wave The same probe on channel 1 would not calibrate. I could not attach video files to this forum, so I can only say that it would not calibrate to anything close to a square wave. I am willing to email the video file to anyone that wants it.

This is what I understand.
10X probe on CHAN2 shows square wave.
10X probe on CHAN1 does not show square wave.

Post photos of oscilloscope screen and scope settings for each case.
Don't send video files. Take photos of the screen and post photos.

 

What are you tweaking? The Probe or the vertical input channel of the scope?

Probe compensation looks like this:



Top High Frequency Accentuation.

Middle Critical Comp (Just Right)

Bottom High Frequency Attenuation.

What are you using for the input signal?

Ron

 

I tried spraying the DeoxIT that I had into the 2 black (dark) portions of the attenuator switch assembly behind channel 1, and it worked!!! (See Photo Attached)

I originally took videos of the oscilloscope screen, because I had the screen showing both traces, so I couldn't take a picture of the screen When I displayed the trace for channel 1 or channel 2 only, I was able to take screen shots.

After spraying, I get a square wave on both channels (See Attached Photos)! Unfortunately, I don't have a before picture of the problem. Anyway, that doesn't matter now.

Thanks to everyone who responded to my postings, especially t_glover!

 

Yay, it works.

Ron