Scope calibration service???

[Kain]

I was just having fun with the PSU from:

http://www.electronics-lab.com/forum/index.php?topic=196.0

and tryed to measure the ripple again. Well I noticed something that I didn't pay attention to before - the scope is actually measuring some p-to-p voltage of about 200mV when used on 5V scale without me feeding any signal in. When i go for 10X probe it goes 800mV without me feeding any input signal. Now, I tryed to read the signal by playing with the trigger but I cannot lock down on anything and on top of that these readings are persistand on all time bases. I haven't had too much experience with scopes, but I am guessing that a calibration is needed. Does anybody in the forum know of a good and cheap

 

[Kain]

Do I get this right or there is no place arround here? I checked for few services but they are all online... and I don't exactly like the idea of shipping the scope to a company , especially outside of CA. C'mon people, if you don't know a place at least say "I don't know"

 

[windoze killa]

Silly question. But have you put your earth lead to a decent earth?

 

[Kain]

Well, so far I have only used it in home and my boss's place and it acts in the same way in either place. I haven't really dig the ground and put some salty water to kill anything that I get my hands on  ;D but given that I have used it on 2 different places and it acts in the same way should tell me something I think. Do you think that I should try to make myself guaranteed good ground to make sure that grounding is not the problem?

 

[windoze killa]

I think you may have missunderstood my question. A CRO probe has an earth/GND lead on it. Sometimes when the probe doesn't have its GND lead connected to GND then there may be some spurious pick up at the tip. There could be a small GND point on the front of the CRO. Try connecting the GND lead to this point and see what occurs. This all assumes that you do actually have this GND lead (normally with an alligator clip on the end).

 

[Kain]

I have already tryed this, and it does not help. In fact this behavior persists even if I have no probe connected at all...

 

[windoze killa]

In this case I would say there is definately a problem. I don't think this is a calibration problem either. I would say there is actually something wrong with it internally. There must be somewhere in your area that can repair it. I am in Australia so I can't recommend anyone.