DC 9V Power Supply Chip Question

dl324

Joined Mar 30, 2015
11,563
A part number for the supply would be helpful. It would also be helpful if you traced the board and made a schematic showing the connections to the damaged part.
 

SamR

Joined Mar 19, 2019
2,597
Possibly a ICL7660S Voltage regulator (or similar) as from what little I can see of the board I can't tell if there is a TO-220 regulator on there.
 

Marley

Joined Apr 4, 2016
362
Looks like it is the switching control circuit as it is on the HV side of the supply.
It may have a high-voltage MOSFET inside, or this may be separate under the PCB.
Hate to say this, but it's not worth repairing!
 

dendad

Joined Feb 20, 2016
3,602
Just from the look of it, I think the bin is the best place for this supply. The power supply does not appear to be designed with good safety in mind. Is there any isolation slots between the primary and secondary sides for instance?
These sort off supplies are very easy to get so I think a replacement is a good idea.
And cheaper than parts to fix the old one.
 

ci139

Joined Jul 11, 2016
1,696
there is a coil wire coating isolation weakening mechanism described in an article - where they show how the channels develop inside the laqcuer over time leading to isolation failure - it might be the primary cause here -- the "short" (over sparking) turns in primary cause core saturation - cause the current peaking (without risen voltage at secondary - so it won't get limited by any means) leading to excessive currents on mosfet - leading to overheating and failure . . .
or
the filter cap next to controller was degrading and caused the chip to fail

... it is unlikely a simple repair
 

Thread Starter

electhobby

Joined Feb 12, 2020
6
Update: I replaced a bad capacitor (Circled in picture) 470uf/25v. When I removed it and tested it, it only had 1.5uf.

Still trying to figure out what chip that is squared below. Thank you.

bad_cap.jpg
 
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