Author Topic: E4406A died PSU  (Read 1692 times)

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Offline Nemo1956

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E4406A died PSU
« on: November 11, 2016, 01:57:29 am »
Hi all. Can anyone help me. I have a HP4406A with a died power supply. I have looked at this for some time but I can get the dam thing working. It seem the stand by +15 volts is missing so it wont do anything.
I need to find a schematic for this power supply but I can find anything on the inter web.

Has anyone had or seen this fault before?  |O
 

Offline strawberry

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Re: E4406A died PSU
« Reply #1 on: November 11, 2016, 06:00:48 pm »
Some pictures can help
What chips?
 

Offline _Wim_

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Re: E4406A died PSU
« Reply #2 on: November 12, 2016, 08:51:45 am »
Check the switching diodes. I had 2 SMPSes were these had broke down. Warning: they measured ok with a multimeter, but there reserve breakdownvoltage was severly lower which caused the malfunction in the SMPS.
 

Offline Bondguy

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Re: E4406A died PSU
« Reply #3 on: November 12, 2016, 08:55:45 pm »
@ _Wim_:If multimeter was not enough, what method did you use to find out that those switching diodes were faulty?
 

Offline _Wim_

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Re: E4406A died PSU
« Reply #4 on: November 12, 2016, 08:58:46 pm »
I desoldered them and replaced by I know good one (after I saw with the scope something was not correct).

But you could also desolder them and put for example 50V reverse voltage on them and check if they conduct any current... This is the problem with the multimeter, the testvoltage is to low...
 

Offline kxenos

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Re: E4406A died PSU
« Reply #5 on: November 12, 2016, 10:34:40 pm »
Here is the service manual:
http://www.keysight.com/upload/cmc_upload/All/E4406-90178.pdf?&cc=GR&lc=eng

Look at page 31. The manual has no schematic diagrams because "The instrument assemblies are not repairable to the component level" (p.14)  |O
 

Offline Nemo1956

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Re: E4406A died PSU
« Reply #6 on: November 21, 2016, 03:07:55 am »
Hi all. That's very interesting about the diodes. I have replaced so leaky caps but still not working.
I will have a look at these diodes. but all I have is a digital meter to test them with. Is there a better way of doing this?
 


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