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Weird fault, need help

Danlove99

May 26, 2022
1
Joined
May 26, 2022
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1
So I'm trying to repair a power supply for an electric recliner. The issue is after the primary transformer I'm supposed to be getting 35V but I'm only getting 7V. I've removed and tested every diode, capacitor and diode junction on the board and everything tested fine. I was touching up a few solder joints I noticed didn't look great and tested it again and suddenly it was working. After leaving it off for a while and then testing it again it goes back to 7V. So it turns out every time I apply heat to the heatsink for the integrated power circuit on the 240V side of the power supply it works temporarily. I replaced the intergrated power circuit with no luck. I'm still a beginner and I've never seen anything like this before so any thoughts would be much appreciated. Thanks
 

Bluejets

Oct 5, 2014
5,991
Joined
Oct 5, 2014
Messages
5,991
Look for any leaky electrolytic capacitor and check (reflow) for dry joints in the solder pads.

Warning...be extremely careful poking around in there with the mains connected in any way.....
AND discharge any electrolytics, especially any larger ones via a resistor BEFORE poking you mitt in once again.
 

kellys_eye

Jun 25, 2010
5,111
Joined
Jun 25, 2010
Messages
5,111
I was touching up a few solder joints I noticed didn't look great
Are you a competent user of a soldering iron? Too often people just re-heat solder joints thinking it will affect a repair when you really need to re-FLOW (new solder/flux) the joint.
 
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