Electronics > Repair
E4406A died PSU
Nemo1956:
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
strawberry:
Some pictures can help
What chips?
_Wim_:
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.
Bondguy:
@ _Wim_:If multimeter was not enough, what method did you use to find out that those switching diodes were faulty?
_Wim_:
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...
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