Author Topic: Agilent MSO-X2012A turns one every other time I push the button  (Read 1732 times)

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Offline craftycoder

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Every other time I press the power button on my Agilent MSO-X 2012A it turns on just two LEDs and freezes. The next time I power it up it behaves as expected. I ran the hardware self test, all good. Any thoughts?

Offline Len

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Re: Agilent MSO-X2012A turns one every other time I push the button
« Reply #1 on: May 13, 2016, 09:09:37 pm »
Every other time I press the power button on my Agilent MSO-X 2012A it turns on just two LEDs and freezes. The next time I power it up it behaves as expected. I ran the hardware self test, all good. Any thoughts?

Sounds like a power supply problem to me. I've seen similar behaviour on a PC, after a while it just wouldn't turn on at all. It turned out to have a bunch of dead electrolytic capacitors.
 

Offline tautech

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Re: Agilent MSO-X2012A turns one every other time I push the button
« Reply #2 on: May 13, 2016, 09:30:16 pm »
Every other time I press the power button on my Agilent MSO-X 2012A it turns on just two LEDs and freezes. The next time I power it up it behaves as expected. I ran the hardware self test, all good. Any thoughts?

Sounds like a power supply problem to me. I've seen similar behaviour on a PC, after a while it just wouldn't turn on at all. It turned out to have a bunch of dead electrolytic capacitors.
+1
PSU is where I'd look first, especially for ripple on any of the rails.

Don't discount dead local caps on the MB either......a PC MB I recapped not long ago displayed exactly the same symptoms and some of the MB caps got so hot they hurt to touch.  :palm:
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Offline craftycoder

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Re: Agilent MSO-X2012A turns one every other time I push the button
« Reply #3 on: May 16, 2016, 12:34:25 pm »
I'll crack open the case and take a look with a thermal camera. The warranty expired 6 months ago. Amazing how well Agilent can design to out live the warranty.

Online nctnico

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Re: Agilent MSO-X2012A turns one every other time I push the button
« Reply #4 on: May 16, 2016, 01:11:24 pm »
I'd start with reseating all the connectors.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline craftycoder

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Re: Agilent MSO-X2012A turns one every other time I push the button
« Reply #5 on: May 16, 2016, 03:14:44 pm »
I cracked open the case and found that the main 420V 100uF nichicon cap was hot and the device had not run all weekend. Presumably the "switch" is a soft switch and the PSU has been running a lot more than I assumed. Note to self, unplug DSO when not in use!

Offline AndyC_772

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Re: Agilent MSO-X2012A turns one every other time I push the button
« Reply #6 on: May 16, 2016, 03:33:07 pm »
Yes, it's a soft switch. Quite why is anybody's guess.

Dave mentioned it in his video review of these scopes; the standby power consumption is surprisingly high.

Offline tautech

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Re: Agilent MSO-X2012A turns one every other time I push the button
« Reply #7 on: May 16, 2016, 03:39:16 pm »
I cracked open the case and found that the main 420V 100uF nichicon cap was hot and the device had not run all weekend. Presumably the "switch" is a soft switch and the PSU has been running a lot more than I assumed. Note to self, unplug DSO when not in use!
Don't go ripping stuff out until you've checked values are to spec, personally I'd suspect the SMPS controller IC power supply chain....either the resistive dropper from rectified mains or the small bulk capacitor on the IC power rail, normally 20-50uF.
The IC datasheet will list what voltages are needed for the SMPS to kick off at and the UVLO voltage, make sure both are maintained. ;)
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Offline craftycoder

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Re: Agilent MSO-X2012A turns one every other time I push the button
« Reply #8 on: May 16, 2016, 04:10:13 pm »
No noise to speak of coming out of the 13V supply. All the low voltages look good at first glance. Seems like it just forgets how to boot up half the time.


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