Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!

[zgr]

Another image.

Does the scope provide power to USB host device when it starts to boot?
In my case i think there could be  some problem with some voltage regulator or step-down converter chip. May be power problem for graphics chip.

My scope is completely dead! I need to fix the P.S at first to know how it will reacts

Hi SAUL BRITTO

I have a same problem with you. Q1 transistor and 2K resistor are dead. Before i will change them, your experience is very important for me. Did you have a chance fix the P.S. and try to open oscilloscope ? Does change the Q1 and 2K resistor enough for fixing?

[Jurkstas]

My scope has same symptoms as this one:


The power supply for my scope shows 13 VDC so it is ok, i think the problem could be with Windows CE boot. Who had the idea to put windows on the oscilloscope

I think you can fix your scope easy by installing open frame 13vdc 200-250W power supply from Mean Well

Which value you need to know?

Hey guy, did you look the screen voltage? maybe a LCD problem...

Hi, I replied to this topic with a very familiar symptom. My scope lights one more LED before halting. LCD voltage is down, because it is disabled. I assume it is only enabled later in boot process. Have you found anything more about this issue?

[Eclipze]

Sharing on a related issue I had just now...

DSO-X 3024A power supply failed.  Didn't turn on... nothing, no lights, not even the fan running.

On the rear of the power supply board, noticed signs of the group of 4x 22kohm resistors overheating (blackened mask).  Noticed the solder was cracked.  Resistance of the resistors themselves was fine, however not with respect to the PCB pads.  Re-soldered the pads and the oscillocope powered up as usual.  Perhaps one of those soldered joins failed and caused the overheating of the others... until another joint cracked.  Repaired, although would have preferred to replace the resistors. Added a small heatsink.

[drvtech]

I stumbled on this thread when I looked up the part number of the PSU in my DSOX2014A. Thought I'd add my two pence worth for future readers. The PSU had gone pop and shorted out the mains input. When I opened it up the main reservoir cap had bulged and it measured about 5uF out of circuit (should be 100uF). Also found Q1 was short. Replaced both parts and PSU came back to life.

Some odd snippets of info:- Q1 is the PFC switch. It should be an STP12NM50. I fitted an IRF840 as that's all I had and I needed the scope today. IRF840 is rated 8A and has higher Rds so I'll have to change it for the correct part ASAP. And I WON'T be leaving it plugged in! Those 22k resistors that Eclipze mentioned are also scorched on my unit and it looks as though they supply the bootstrap voltage to the PWM chip, which explains why his wouldn't start up at all.

When I bought this scope it was partly on the strength of Dave Jones's tear down and I had always assumed that the mains switch was a real mains switch which turned off the supply. It is now apparent that it does not so all those years (about 8 ) of leaving my scope plugged in have meant that it was sitting there with 400V on the reservoir cap. No wonder it dried out.

Anyway, hope the above is useful
DrV

[mngiggle]

Landed here for the same reason with an MSO-X 3054A scope; bulging cap, plus scorch marks around the FETs. (Although it looks like ours is mechanically switched, so maybe it's not just sitting plugged in that's the problem.)