Very Basic Oscilloscope Questions

[ataradov]

This is most definitely not normal. But it may be a bit too early for the repair service.

1. Can you note what adjustments you need to make for calibration? Like approximate portion of a turn if the cap in the probe and what direction? Does it just go back and forth between power cycles to stay calibrated?
2. Can you connect the output of the test signal generator directly to the input of the scope without a probe?

[HoracioDos]

I forgot to tell I never changed the probe. It's always the same.

1. Can you note what adjustments you need to make for calibration? Like approximate portion of a turn if the cap in the probe and what direction? Does it just go back and forth between power cycles to stay calibrated?

OK, I'll take more detailed notes. I never remember if I turn left or right but It's always less than a quarter of a turn. I have to calibrate it every time I turn on the dso if the probe is 10X. I have 1x-10x default probes. Once in a while it seems that it starts to drift if it was turned on for many hours.

2. Can you connect the output of the test signal generator directly to the input of the scope without a probe?

Yes I could. I should buy a BNC adapter and I think I have a little piece of RG58 somewhere.

[ataradov]

Yes I could. I should buy a BNC adapter and I think I have a little piece of RG58 somewhere.

Do this and observe if signal changes at all over some time. I'm basically trying to eliminate faulty probes.

[alsetalokin4017]

This may be a bit silly... but are you quite sure the spring grabber tips are completely in place on your probes? For the stock probes that come with the DS1054z, these tips need quite a push before they click solidly in place. And even then, they may not make good contact without rotating them a bit. A poor connection to the grabber tip might cause the kind of thing you are seeing.
You could try pulling the grabber off the probe and just using the sharp tip, to see if that makes any difference in the compensation drift.

[ProBang2]

Hmmm...

Seems like totally normal behavior to me. (At least, mine does the same...)

The direct (with BNC to croc-clip cable) connected calibration signal shows a perfect rectangular 3V_PP wave.
All four probes have the same drift after calibration. (Not immediatly. After some time.)

Possible explanation:
The wiper of the calibration trimpot in the probe is made of a cheap metal (maybe aluminium).
This metal is oxidizing when in contact with air. It builts up a layer of oxid on the surface.
This layer prevents the inner part of the metal from further oxidising.
If the wiper is moving while a calibration, then some oxid is scratched of the surface.
After calibration it begins to oxidising again, until the surface is complete covered.

Possible remedy:
Apply some contact-spray or much more simple, a little amount of oil to the trimpot(s).
This covers the metal surface, avoiding the contact between metal and air and thereby the oxidation.
Then there is no more ongoing oxidation, hence the electrical parameters of the trimpot should be stable.

[metrologist]

Why there's an Auto setup button if It's so bad to use it?

Because sometimes you are in the lab, where you have to use shared scopes, and it is easier to restore a scope to some known state and start from there.

If you know exactly how your scope is set up, then there should be no need for auto button, unless you are absolutely confused.

On my own equipment, AUTO button disorients me, and after using it I have to go back and check all the settings again, since it is very unpredictable what exactly will be changed as a result.

I would like to remap the Auto set button to the Default button. I can't remember what I was doing last time, and with this scope it's just easier to remove measurements and some configurations by going full default.

[metrologist]

The probe compensation on mine will drift too. I worked the trim pot full sweeps a few times. I also noticed touching that switch impact the cal. I think the probes are the issue with cheap trim pot and that silly switch. The probes otherwise seem OK, or usable anyway.

[HoracioDos]

This may be a bit silly... but are you quite sure the spring grabber tips are completely in place on your probes? For the stock probes that come with the DS1054z, these tips need quite a push before they click solidly in place. And even then, they may not make good contact without rotating them a bit. A poor connection to the grabber tip might cause the kind of thing you are seeing.
You could try pulling the grabber off the probe and just using the sharp tip, to see if that makes any difference in the compensation drift.

I love this kind of solutions. I'm testing the probe again.

[HoracioDos]

Yes I could. I should buy a BNC adapter and I think I have a little piece of RG58 somewhere.

Do this and observe if signal changes at all over some time. I'm basically trying to eliminate faulty probes.

I've just bought the BNC adapter. I hate to solder these things! I'll try it tonight.

[StillTrying]

Is there any change over time at all in the 1khz when the probes are on X1.

Have you tried a different square wave source, it doesn't have to be exactly 1khz nor exactly 3v.

Do you remove the probes before doing its self-calibration.

[AG6QR]

I don't use the "AUTO" button to fully set everything.  I didn't have an "AUTO" button when I first learned to use a scope, and old habits die hard.  The way I learned was the following:

• Set the trigger mode to Auto.  This guarantees that the beam will sweep the screen periodically.
• Turn the vertical scale knob to zoom out.  That is, toward the largest volts per division available.  You don't necessarily need to go all the way -- you can stop when you see both the top and bottom of the trace.
• If zooming out all the way didn't already give you a trace, click on the "position" knob, and if needed, rotate it a bit.
• Once you see a trace, use the scale and position knobs to zoom in on it so that it covers a reasonable portion of the vertical extents of the screen.  Don't worry about triggering just yet.
• Adjust the horizontal scale as desired.
  
• Now set the trigger level to somewhere in the middle of the waveform to get a stable trace.
• Fine tune things as desired

With just a bit of practice, these adjustments become second nature, and you can do them very quickly.  You may not do them precisely in this order every time.  But the basic idea is, zoom out, find the trace, then zoom in on it.

[tautech]

Probes
It is unnessary to compensate probes on 1:1 setting, only do so on 10:1 settings.