mercury pc power supply only 5vsb supply.

[R_J]

Re: mercury pc power supply only 5vsb supply.

Remove this jumper wire to isolate the circuit. This way the only components that are connected to the end of the resistor are within the yellow box. If the voltage is still less than 1 volt, there must be a bad transistor or diode in this area

[playit]

Re: mercury pc power supply only 5vsb supply.

should i check voltages in D9/D10 again to be sure?? hmm by keeping positive probe on positive points of this 2 diodes ?

[playit]

Re: mercury pc power supply only 5vsb supply.

so whats the problem.. what should be changed? am not getting 12 v at other side of the resistor..what point to be checked now?

[R_J]

Re: mercury pc power supply only 5vsb supply.

Yes that looks corect, the resistor supplies the 16 volts to the two transistors that drive the small transformer. It also supplies the voltage through one of the small diodes (D10?) then through R32 that connects to another part of the circuit, likely the wt7520 ic .

[playit]

Re: mercury pc power supply only 5vsb supply.

here i guess i attached the links correct..

[playit]

Re: mercury pc power supply only 5vsb supply.

in 2000k ohms mode, black probe in black wire , red probe at low voltage gives 775 ohms, at 16v point -777 ohms

[playit]

Re: mercury pc power supply only 5vsb supply.

hmm.. i kept the black probe in ground ,but with no power, i kept the positive probe on end of low voltage point-- its 590 in diode mode and 645 ohms in ohms mode

[playit]

Re: mercury pc power supply only 5vsb supply.

when i kept opposite from the junction ,i.e the negative of D9 and positive of D 10 ,i am getting value in diode mode ,before i dint get that.
how to measure the resistance to ground?

[R_J]

Re: mercury pc power supply only 5vsb supply.

I dont understand? "but now the 4148 diodes give reading when touched together both at one side"
What is the resistance measured to ground on the end of the resistor that has the low voltage?

[playit]

Re: mercury pc power supply only 5vsb supply.

hi ,i connected the traces like in the pic,i get the same results .. 16v at one end and 0.76v at other end of resistor.. but now the 4148 diodes give reading when touched together both at one side,did i miss anything?

[playit]

Re: mercury pc power supply only 5vsb supply.

if it helps.. i found the model number but couldnt get it from internet.. mercury model ckp-3400 gc14244 -- this was written on the box of this power supply lid

[playit]

Re: mercury pc power supply only 5vsb supply.

oh ya cool.. now i see the point

[R_J]

Re: mercury pc power supply only 5vsb supply.

hmm ok nods ..i dont have schematics ..i mean like a circuit diagram but yes.. i saw they are all over the board.. just wanted to be sure if i am messing up amymore.. today i will fix the tracings and see what i get

Look at Post #8.... It is not the EXACT schematic but is very close.

[playit]

Re: mercury pc power supply only 5vsb supply.

hmm ok nods ..i dont have schematics ..i mean like a circuit diagram but yes.. i saw they are all over the board.. just wanted to be sure if i am messing up amymore.. today i will fix the tracings and see what i get

[R_J]

Re: mercury pc power supply only 5vsb supply.

There are lots of 1N4148 diodes in this power supply, Plese look at the schematic and you will see they are used everywhere. The two diodes (D9,D10) are likely the same as D10 and D15 on the schematic.
On one side of R23 you should have 16v on the other side it could be around 10~12 volts?

[playit]

Re: mercury pc power supply only 5vsb supply.

transistors readings in post #49 are ok?

[playit]

Re: mercury pc power supply only 5vsb supply.

thank you for replying.. i will do it.. after doing it what voltage should i expect on the other side of resistor ? and i am confused whether i really saw 2 4148 diodes ? is that correct there would be 2 4148 there or i am mistaken for some other diodes ?

[R_J]

Re: mercury pc power supply only 5vsb supply.

This is how the trace should be. and this is how to connect that 1.5k resistor. You need to connect the RED diode anode to the grey jumper wire (yellow trace)
One end of the resistor can connect to the jumper wire and the otherend to the blue diode cathode.

Your R23 should be the same as R24 on the schematic

[playit]

Re: mercury pc power supply only 5vsb supply.

should d9 and d10 to be soldered or shorted in someway..
what could be the reason for not getting 16 v or any voltage at other side of the resistor.. any idea how the circuit joins with 2 x 4148 and a resistor.. ? i tried to google it..not much help there..

[playit]

Re: mercury pc power supply only 5vsb supply.

d10 positive has continuity with the copper foil near the junction..i tested the continuity,so according to old pic in which i dint rip off .. are these junction/d10 4148 positive/resistor all soldered together?