Hello NADATHO,
Just stumbled across this thread. I laughed because you sound like me. I have the exact same power supply and I also have 3 other better power supplies but I want this one fixed.
You've probably moved on maybe tossed the unit.....but I'm still working on mine.
I can confirm I am reading the exact same things you are on yours. The 2-3-2 pin side of the transformer, all the pins are shorted together. so now I assume from your post that that is normal for this transformer. I was also getting the shorted power rails like you.
I messed mine up by accidentally connecting it reverse voltage to a 12v battery I was going to charge with it.
I checked nearly every component on the entire board and I found just a few things.
1). There was a burnt out section of track located on the bottom side of the board under C31 near the large coil inductor.
2). P75N75 Mosfet was blown
3). The two black NTC thermistors RT1 and RT2 both had very high resistance above specs so they were replaced.
4). Both IRF840's had high On State drain to source resistances and were replaced.
Everything else seemed ok. I'm still waiting on a few parts to finish it.
I'm wondering if either or both of the IC chips were damaged (TL494CN and TL084CN)
To that end, I'm building a test circuit for them so that I can test that they are both ok.
I'm wondering if the short we are both experiencing could be in those IC chips?
I'm doing this as a learning project. It has nothing to do with the value of the Power Supply as a power supply.
I have already repaired 2 Meanwell power supplies and a 48v ebike battery charger so it's all in the name of learning.
On my bench now is a battery pack from a Bissell Car Vacuum, a Power Inverter and a hard drive SMD controller board.
Starting to practice with replacing SMD components.
Anyway, if you fixed your 30v 5A PSU I'd sure like to hear about it. If it's still on the list of to do's maybe we could share info and help each other?
Moderator Edit: New thread created from here:
https://forum.allaboutcircuits.com/threads/help-30v-5a-3-outlet-transformer-bench-supply.174301/
Just stumbled across this thread. I laughed because you sound like me. I have the exact same power supply and I also have 3 other better power supplies but I want this one fixed.
You've probably moved on maybe tossed the unit.....but I'm still working on mine.
I can confirm I am reading the exact same things you are on yours. The 2-3-2 pin side of the transformer, all the pins are shorted together. so now I assume from your post that that is normal for this transformer. I was also getting the shorted power rails like you.
I messed mine up by accidentally connecting it reverse voltage to a 12v battery I was going to charge with it.
I checked nearly every component on the entire board and I found just a few things.
1). There was a burnt out section of track located on the bottom side of the board under C31 near the large coil inductor.
2). P75N75 Mosfet was blown
3). The two black NTC thermistors RT1 and RT2 both had very high resistance above specs so they were replaced.
4). Both IRF840's had high On State drain to source resistances and were replaced.
Everything else seemed ok. I'm still waiting on a few parts to finish it.
I'm wondering if either or both of the IC chips were damaged (TL494CN and TL084CN)
To that end, I'm building a test circuit for them so that I can test that they are both ok.
I'm wondering if the short we are both experiencing could be in those IC chips?
I'm doing this as a learning project. It has nothing to do with the value of the Power Supply as a power supply.
I have already repaired 2 Meanwell power supplies and a 48v ebike battery charger so it's all in the name of learning.
On my bench now is a battery pack from a Bissell Car Vacuum, a Power Inverter and a hard drive SMD controller board.
Starting to practice with replacing SMD components.
Anyway, if you fixed your 30v 5A PSU I'd sure like to hear about it. If it's still on the list of to do's maybe we could share info and help each other?
Moderator Edit: New thread created from here:
https://forum.allaboutcircuits.com/threads/help-30v-5a-3-outlet-transformer-bench-supply.174301/
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