My PCSU1000 is failing the calibration test on Ch2. I have had the unit for just over a year. It is used for hobby electronics - PIC, Arduino etc. Occasionally it is used with PCGU1000 function generator for Bode plots. It is used with an Acer laptop running Windows 7 64-bit Home Premium.
For the first few months I had the unit it would always pass the calibration test when exiting the PCLab software. Then it went through a period of failing on Ch2 periodically but this could be fixed by unplugging the unit from the USB port and plugging back in (it would sometimes freeze during the test). The last few weeks the unit has failed on Ch2 every time it has been used but was close to the Ch1 calibration values. Today the unit will not calibrate on Ch2 at all and the values for low, middle and high triggers are almost the same. Does this indicate some kind of progressive failure inside the unit?
I have tried the fixes mentioned on the forum to delete the WinDSO file. I have tried calibrating with and without probes attached (not-connected to external circuits obviously) - this makes no difference.
My calibration results file is shown below.
Any help you can provide would be appreciated.
Calibration results:
CH1 offset at 2V/div : 119 OK
CH2 offset at 2V/div : 118 OK
CH1 offset at 1V/div : 0 OK
CH2 offset at 1V/div : -1 OK
CH1 offset at 0.5V/div : 1 OK
CH2 offset at 0.5V/div : -1 OK
CH1 offset at 5us/div : 1 OK
CH2 offset at 5us/div : 1 OK
CH1 Y-position low 31
CH1 Trigger : 54
CH1 Trigger : 42
CH1 Trigger low : 48 OK
CH1 Y-position mid 127
CH1 Trigger : 97
CH1 Trigger : 85
CH1 Trigger middle : 91 OK
CH1 Y-position high 224
CH1 Trigger : 140
CH1 Trigger : 127
CH1 Trigger high : 134 OK
CH2 Y-position low 0
CH2 Trigger : 255
CH2 Trigger : 0
CH2 Trigger low : 128 OK
CH2 Y-position mid 0
CH2 Trigger : 255
CH2 Trigger : 0
CH2 Trigger middle : 128 FAIL
CH2 Y-position high 224
CH2 Trigger : 141
CH2 Trigger : 125
CH2 Trigger high : 133 FAIL
EXT Trigger middle : 51 OK
For me I tried five times in a row and it failed each time, then the sixth time it passed. I just tried again today. The first time it failed, then the next time it passed. It seems to be an intermittent problem. Note as I said this is a brand new scope, just out of the box. The scope seems to be working nalthough I have not yet used it for anything sophisticated.
I’m sorry for the inconvenience.
This is very strange problem indeed.
It seems this may be some sort of compatibility (or USB communication) issue.
I think you can use the scope after successful calibration.
I couldn’t use Ch2 after the failed calibration. The trigger did not work (per the failure in the calibration log file) and so the display for Ch2 would freeze while the scope waited for the trigger. I was using the test signal on the back of the scope. Ch1 works fine. Is this a hardware failure?
You can do following test:
Using any text editor (e.g. Notepad) open the file WinDSO.ini located in the folder:
C:\Users<your username>\AppData\Local\VirtualStore\Program Files (x86)\Velleman\PCLab2000SE
Replace the section starting with “[Calibration_1000]” with the following data:
[Calibration_1000]
trg_ch1_min=48
trg_ch1_mid=91
trg_ch1_max=134
trg_ch2_min=48
trg_ch2_mid=91
trg_ch2_max=134
trg_ext_mid=51
offs_1=119
offs_2=118
v5_offs1=0
v5_offs2=0
v15mv_offs1=0
v15mv_offs2=0
v5mv_offs1=0
v5mv_offs2=0
f5us_offs1=0
f10us_offs1=0
f20us_offs1=0
f5us_offs2=0
f10us_offs2=0
f20us_offs2=0
Ch1_pos0=127
Ch1_pos1=32
Ch1_pos2=224
Ch2_pos0=127
Ch2_pos1=32
Ch2_pos2=224
Ch1_ad0=125
Ch1_ad1=80
Ch1_ad2=169
Ch2_ad0=123
Ch2_ad1=77
Ch2_ad2=167
Save the modified WinDSO.ini.
Then run the PcLab2000SE software and test if the PCSU1000 oscilloscope is working OK.
If OK then there is no hardware problem.
It seems there is some sort of Windows 7 compatibility or USB communication issue.
If this is the case, sending the oscilloscope to Velleman doesn’t fix the problem.
Now there is only one defective result in the calibration results.
You may try to get successful calibration result by selecting Options -> Calibrate.
If the calibration succeeds you can then use the oscilloscope and no new calibration is needed.
Alternatively you may also calibrate the oscilloscope in other PC and copy the whole WinDSO.ini from the other PC to your PC.
One possible solution may be to slow down the computer speed during the calibration.
Click on the battery symbol in the taskbar and you should get a popup menu that will allow you to choose the power saving options.
Change the power settings to “Power Saver” or to any battery saving option there.
You may also make a right mouse click on the battery symbol in the taskbar and choose “Power Options”. There you can set the battery saving mode.
[quote]Why does this work when the calibrate on exit fails?[/quote] This is very strange. The calibration procedure is identical in both cases. The only difference is that the software is closed in the other case just after the calibration.