24 VDC COSEL Power Supply Repaired
A customer brought this power supply in for repairs and said the complaint was that he was not getting the 24 VDC out to power his machine. I ask him what is his supply volt in his shop, he told me he was getting a 240 Voltsupply which is correct for the power supply. First thing I did when I open the unit was to check the fuse and it check good, second thing was to check the circuit board for any damage component and everything seem to check out find.
I then proceeded to put power to the unit and see what was going on. There was no output as the customer said.
Note : I do not have a 240VAC supply in my shop so I had a Toroidal Transformer handy so I use it to step up to the required voltage.
I began checking from the bridge rectifier and got the 300 VDC, next was the Filter Cap and I got my voltage present. Next was the Input of the power IC and I got my 12 VDC which was good.
I still suspected this IC so I check the output and got my voltage present, next was to check the secondary voltage which was also present. I got a little confuse as to what was the problem so I did a close up inspection on the board through my 10X Magnifying Glass and I came across a Broken track which is very difficult to see with the naked eye. I use a piece of copper wire to rejoin the track and I applied power to the unit and it came back to life.
If you have done all your trouble shooting correct and measure all you component correct, chances are you may have cold, dry soldering or a broken track as this power supply had.
This article was prepared for you by Andre Gopee from Calitech Limited Trinidad West Indies.
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salvi
June 4, 2023 at 2:35 pm
please alternate diode used in FCA75F-24 cosel power supply 24v--3A
between 2sk3878 pin 2 and pin2---3878
other 3878 pin 1 and pin1---3878