160v??
where does that come from? he's got 340v dc after the rectifier.
It should have been 340vdc, I overlooked that he was in the U.K. next time I will just call it Main B+ EDIT
The small smd transistor drives a larger mosfet that has it's Drain pin connected to the small standby transformer, I made a Red square around the standby mosfet and a yellow one around the drive transistor.
On the small standby transformer, pin 1 should have 340vdc, and so should pin3 which is connected to the mosfet drain., this is the primary. There is likely a low ohm resistor connected to THIS mosfet's source pin to hot ground.
The small smd transistor drives a larger mosfet that has it's Drain pin connected to the small standby transformer, I made a Red square around the standby mosfet and a yellow one around the drive transistor.
On the small standby transformer, pin 1 should have 160vdc, and so should pin 3 which is connected to the mosfet drain., this is the primary. There is likely a low ohm resistor connected to THIS mosfet's source pin to hot ground.
That's a great help RJ. Ok I took a reading on all you said and I dont get a voltage on Pin 1 of the standby transformer (my meter just goes straight to zero whatever that means) although I do get -310vdc on pin 4 and -310vdc at all 3 pins of the smd transistor.
I am not sure if I am putting the negative meter probe at the correct place. I am taking the negative from the negative output of the Rectifier but all readings are -voltages which seams wrong. I always get confused where I should be taking the negative from especially on the AC side. I guess if I take it from negative output of Rectifier its got to be right (I hope). I also get a high pitched sound when turning the PSU on or off. Its what sounds like its in pain lol...
Thanks RJ for that Schematic and thank you everyone for your help.
Thanks to you all I have finished repairing these PSU's and all the computers they go in are working again.
Thanks!
Some more items that did not land into the landfill
Go repairs
9 PC LCD Monitor
6 LCD Flat Screen TV
30 Desk Top Switching Power Supply
10 Battery Charger Switching Power Supply for Power Tool
6 18v Lithium Battery Power Boards for Tool Battery Packs
1 XBox 360 Switching Power Supply and M Board
25 Servo Drives 220/460 3 Phase
6 De-soldering Station Switching Power Supply 1 Power Supply
1 Dell Mother Board
15 Computer Power Supply
1 HP Printer Supply & Control Board * lighting finished it *
These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%
1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
2 Hem Saw Computer Stack Board
All of these had CAPs POOF
All of the mosfet that are taken out by bad caps
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