Damaged screen and square wave probe test signal

Instruments HPS140 Handheld Pocket Oscilloscope
1

I have two problem with the HPS140 I have just bought from Maplin.

  1. There is a scratch, about 2 mm, on the inside of the screen which appears black when turned on. When it is turned off you can see the scratch and the shadow it casts on the LCD. Shows rather poor quality control!
  2. I dont understand the probe test signal. I did not buy your probe as I have two RS Components probes with X1 and X10. I have set it to X10 and the menu to X10 and all I get from touching the test point is a very small change in level with the noise being more than the level change. Advice please.
2

Sorry to read you experience troubles with your HPS140 pocket scope.
A scratched screen should never have passed QC.
We recommend to return the unit for repair/exchange.

3

OK, will see if I can that in my local Maplin as dotn want all the bother of packaging up etc. Can you answer the second point please?

4

Without further info, we have to conclude that either the probe is defective or the scope was not set to a correct V and time/div.
Try auto-setup. If you do not get a square wave when using auto setup, most likely the probe is defective.

5

Problem with thinking the probe is defective is I have two RS Components probes which work OK on my old, very large, valve oscilloscope. I also have a simple probe. Setting the RS ones to x10 and the scope to Auto volts and auto time and x10 achieves nothing! Is there something unique about your probe?

6

No, it is a standard probe.
Does the scope work, or is it just the calibration output that does not seem to work?

7

Just the calibration. However, I am just going to Maplin in Southampton to change it because of the scratch on the inside of the screen. Hence, wait and see if the new one is different.

8

OK.
Just make sure the probe tip touches the test pad.
Some probes are too large and don’t go all the way down to the test pad.