mercury pc power supply only 5vsb supply.

[playit]

Re: mercury pc power supply only 5vsb supply.

i dint get the resister in my area will have to go 1 hour journey to get that ,is there anything else i would have to buy .. and in post #25 "the red(big) and brown colored big diode you marked gives beep in continuity (50 number at both sides) , pink color diode- gives 450 negative probe to positive probe and reversed gives 1526 "

is it ok for a diode to give same number and beep at both sides?

[playit]

Re: mercury pc power supply only 5vsb supply.

i checked three orange diodes around that transistor(zener glass diodes i guess),they all gave readings similar to post #27, and the 2 orange diodes closer to r23 gives reading around 523 only when with negative to positive ,reverse gives no reading.

[R_J]

Re: mercury pc power supply only 5vsb supply.

There is only one zener diode that I marked, it is ok because you have +5 volts on it. The other diodes I marked are just regular glass diodes, likely 1N4148. there were two next to R23 and two next to the transistors (I marked EBC)

[playit]

Re: mercury pc power supply only 5vsb supply.

oh ok , will get the resister after few hours here and the diodes reading marked in green-- horizontal zener diode- negative probe to positive- 520 and reversed 1072.
vertical zener diode - -ve to +ve probe- 523 and reversed 1073,are they ok?

[R_J]

Re: mercury pc power supply only 5vsb supply.

All those components are likely ok, I ment to check the diodes I marked green and the transistors on the drive transformer, if those transistor readings were for those transistors, they are likely ok. I would try replacing that R23 with a 1.5K and see what happens.

[playit]

Re: mercury pc power supply only 5vsb supply.

the red(big) and brown colored big diode you marked gives beep in continuity (50 number at both sides) , pink color diode- gives 450 negative probe to positive probe and reversed gives 1526 .

transistor vertical pins - black probe in middle- 690 and 537 ,reversed gives 1144 at one side and nothing at other side.
transistor horizontal pins- black probe in middle- 600 and 542,reversed gives 1155 at one side and nothing at other side.

[R_J]

Re: mercury pc power supply only 5vsb supply.

Check the parts with power disconnected. check that none of the parts are shorted.
Check the diodes and transistors using diode test on your meter, The reading is usually around .6xx for a diode one way and open the other way. for the transistors check them from base to collector and base to emitter, then reverse the leads and repeat the test, then check between collector and emitter (this should check open)

[playit]

Re: mercury pc power supply only 5vsb supply.

what to chek in 2 diodes ,transistors? what reading should i see? volts or continuity?
what points to check in transistors?

[R_J]

Re: mercury pc power supply only 5vsb supply.

Then R23 is open, I don't know what it's value would be, it might be a 1.5k ½watt. I checked a couple schematics and they both used a 1K in that position. Before replacing it, Check the two diodes on the other side of of the board of R23. Also check the two transistors and the 2 diodes that are connected to that drive transformer.

[playit]

Re: mercury pc power supply only 5vsb supply.

oh thers a mistake in my post 19.i misunderstood the both sides wrong and i tested one of r32 which showed 16v, and by the way.. only one side of r23 shows 16v and 0.6 v at other side of r23 which connects with jumper.

[R_J]

Re: mercury pc power supply only 5vsb supply.

i tested the voltage at drive transformer point- its 0.72v and r23 both sides is 16.23 v

There should be a jumper wire from R23 across to the trace that connects to the drive transformer, This 16v supplies the two transistors via the drive transformer.

[playit]

Re: mercury pc power supply only 5vsb supply.

i tested the voltage at drive transformer point- its 0.72v and r23 both sides is 16.23 v

[playit]

Re: mercury pc power supply only 5vsb supply.

oh ok, so whats next i should test now ? also the ic chip is good as per your 5 v test?

[R_J]

Re: mercury pc power supply only 5vsb supply.

now what should i check,could you also please tell me where should i keep the black probe and red probe ,because last time.. i took little help from youtube :P ,thanks for teaching me

When checking voltages on the hot side, use the negative of the large cap or the negative of the bridge rectifier. In this case there are two large caps so you must use the one connected to the negative of the diode bridge, NOT the negative of the other large cap.
For cold side use the output ground

I gave some test points in post #14

[playit]

Re: mercury pc power supply only 5vsb supply.

now what should i check,could you also please tell me where should i keep the black probe and red probe ,because last time.. i took little help from youtube :P ,thanks for teaching me

[playit]

Re: mercury pc power supply only 5vsb supply.

last time i did the hot test.. i kept the black probe at negative in large filter capacitor at input side and red probe at vcc pin.. now i am not sure if i kept it good.. oops.. but now i did as in post #13 i get 5v in vcc and 2 caps you suggested to check

[R_J]

Re: mercury pc power supply only 5vsb supply.

So you do have +5v vcc on the ic. not 0.5v like in post #7
Check the voltage on the drive transformer (check voltage here). If there is no voltage there, check on boths sides of R23, I suspect it might be open.

[playit]

Re: mercury pc power supply only 5vsb supply.

i kept black probe of multimeter in black wire of outlet psu wire ,shorted green black wires, at vcc pin 13 i got 5 v,both capacitors positive points got 5v with red probe.

[R_J]

Re: mercury pc power supply only 5vsb supply.

Can YOU trace pin 13 of the ic based on this picture? You have the board, pin 13 needs +5 volts but has 0 volts, This is the best I can do, there seems to be a coil (marked in green) Chck that you have +5v on the two caps I marked.
There seems to be a jumper wire (J0) next to the GP marking, It looks a bit corroded, check it.

[playit]

Re: mercury pc power supply only 5vsb supply.

is this pic ok?