Electronics > Repair
DSO-X 3024A Power Supply defect
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EE-digger:
The NAND issues have been masked by redundancy and error checking.  The NAND chip has a life of 10 years on paper (Micron). 

It would be nice if someone could identify the SMPS used in scopes of recent builds.  It only takes 5 minutes to peek at it.  If it's the same model, that's disappointing.  If it's changed, an ID might help with replacements.

EE-digger:
In the good old days (and now), HP and others would keep power on for critical areas (oscillators, converters, etc.).  Some of those are now in the 40 year old range and still trucking.  Enter the SMPS ...

This SMPS power supply failure issue, especially when explosion of one or more components is involved, is disturbing enough to take affirmative action.  For someone who keeps his cars ~15 years or more, the expensive little oscilloscopes is a close second.

For our off shore friends running on 230v ac mains, the picture is not so good.  For 120v, the resistors should pose no problem.  From calculations, dissipation in each of the 22k resistors and approximate temperature rise for the mounted part is:

120vac - 0.08 watts - estimated temperature rise 15 to 20 degrees
230vac - 0.3 watts - estimated temperature rise 45 to 55 degrees

Add this to the temperature rise of the cap itself from ripple dissipation and you have a bad picture for 230v.  Credit to poster rolkinas in reply #53 of this thread for his bleed resistor measurements.

The killer is that if your scope is plugged in (most labs) this heat rise is constant.

After finding several excellent quality supply replacements, I decided to replace only the cap with an 8000 hour part and change the resistors to 56k each.  Combined, this should allow the scopes to last a LONG time.

added - the above assessment was incorrect.  The main capacitor has 390 volts across it on a 120v ac line.
CapLeaker:
Here is my run in on a Agilent DSO-X2012 power supply if that helps anyone.
https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-game-consoles-other-weird-devices/86804-agilent-dso-x-2012a-no-power-repair
EE-digger:
Thanks.  It points further at that cap.  If an earlier poster is correct, that cap is rated for 3000 hours.  That's only 4 months.

Under "normal" use, this would stretch into years but with the resistors under it, all bets are off.  You're in Canada though so the heat rise in that group wouldn't have added a whole lot but still could have been another 20 degrees C.

I have two DSOX, one coming in from Keysight repair shortly.  I'm going to open and look at both with an IR camera.  I'll lose the forced air but this supply should easily handle the moderate load (from what I see on bench supplies).  One scope is 2016 and the other is 2013 vintage.

They are usually not supplied with ac so may appear more like new-ish.
CapLeaker:
I do know that Agilent didn’t make the power supply at least not for my 2012. It was a third party power supply. Look at my post at Badcaps, I had uploaded the flyer from Cherokee. At least they are easy to fix. If I remember right, the biggest problem of my repair was to find a capacitor that actually fit.
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