Got this non working ATX power supply from a garage sale. The owner is not too sure if it is working. I noticed it is label as Sunshine Model ATX235 Series Rev 5. After opening the case,i saw THR 1 is empty;so I soldered in a SCK084 thermistor. Checking other area I don't see any burn marks and the 5A 250V fuse tested good in continuity.
Before I switched on the ps,I soldered in a 60W light bulb in series in place of the fuse. By shorting the green wire to black ground wire, I switched on ps, the light bulb glows shortly then dims off. I checked the purple wire with a DMM, it reads 4.9VDC meaning there is standby power. But checking on yellow wire or red wire doesn't show any voltage on DMM.
I also checked on the 16pin chip pwm IC KA7500B, put my red probe to pin 12 while black probe to pin 7 shows 5VDC.
Then I unsoldered all the secondary caps and I make sure ESR reading on yellow rail caps of 470UF 16V tested good since ESR reads<0.20 ohm.
The caps on black rail of 680UF16V & 680UF10V ESR reads<0.10 ohm while the caps on red rail of 680UF10V tested good since ESR reads <0.10 ohm.
I also tested ESR on smaller caps on C27(1UF50V reads 3 ohm),
C33(0.68UF50V reads 3.5ohm),C40(4UF50V reads 1.4 ohm) & C45(1UF50V reads 3.4 ohm). All ESR reading on these four small caps are within good range.
By setting my DMM to diode test, off board the diode FR103 on D15&D19 along heat sink2 reads 466 on one side while "1" on the other side. Both diodes are not shorted or open.
Then I did diode test on 3 transistors on heatsink 1 which are C5027, and 2 units C2335F. The diode test doesn't find any short or beeps.
I did diode test on schottky rectifier on heatsink2 which are double diode(can't see the type), PSR16C40CT and MOSPEC S10C40C. Black probe to cathode middle pin and red probe to left and right anode pin
both shows around 79 ohm. The basic result seem to conclude there is no shorts. Refer to img 1897 on back of pcb, I saw a connecting black wire and
zener diode and wonder if this is supposed to be here?
But I have no idea how to test the two big main cap and the black square bridge rectifier. FYI, on hand I have a digital multimeter,a 40W soldering gun, a china made ESR tester(M Tester v2.07) and a digital capacitor meter.
I will appreciate anyone kind and generous to advice on what to do next to revive this ps.
Before I switched on the ps,I soldered in a 60W light bulb in series in place of the fuse. By shorting the green wire to black ground wire, I switched on ps, the light bulb glows shortly then dims off. I checked the purple wire with a DMM, it reads 4.9VDC meaning there is standby power. But checking on yellow wire or red wire doesn't show any voltage on DMM.
I also checked on the 16pin chip pwm IC KA7500B, put my red probe to pin 12 while black probe to pin 7 shows 5VDC.
Then I unsoldered all the secondary caps and I make sure ESR reading on yellow rail caps of 470UF 16V tested good since ESR reads<0.20 ohm.
The caps on black rail of 680UF16V & 680UF10V ESR reads<0.10 ohm while the caps on red rail of 680UF10V tested good since ESR reads <0.10 ohm.
I also tested ESR on smaller caps on C27(1UF50V reads 3 ohm),
C33(0.68UF50V reads 3.5ohm),C40(4UF50V reads 1.4 ohm) & C45(1UF50V reads 3.4 ohm). All ESR reading on these four small caps are within good range.
By setting my DMM to diode test, off board the diode FR103 on D15&D19 along heat sink2 reads 466 on one side while "1" on the other side. Both diodes are not shorted or open.
Then I did diode test on 3 transistors on heatsink 1 which are C5027, and 2 units C2335F. The diode test doesn't find any short or beeps.
I did diode test on schottky rectifier on heatsink2 which are double diode(can't see the type), PSR16C40CT and MOSPEC S10C40C. Black probe to cathode middle pin and red probe to left and right anode pin
both shows around 79 ohm. The basic result seem to conclude there is no shorts. Refer to img 1897 on back of pcb, I saw a connecting black wire and
zener diode and wonder if this is supposed to be here?
But I have no idea how to test the two big main cap and the black square bridge rectifier. FYI, on hand I have a digital multimeter,a 40W soldering gun, a china made ESR tester(M Tester v2.07) and a digital capacitor meter.
I will appreciate anyone kind and generous to advice on what to do next to revive this ps.
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