Dps-240fb

[ben7]

Re: Dps-240fb

It is:
- STPS10L 4OCT
- L7912CV

Could you measure the resistance of the 5v standby to ground?

Next, what is the voltage from the center pin of the STPS10L40CT, to ground? (With the part soldered in)

When you measured the 5v standby before, did you have all the other components soldered in? If so, check your solder joints, and check to make sure you didn't make any solder bridges.

[rtstorm]

Re: Dps-240fb

resistance is 385 Ohm,
voltage from center of STPS10L40CT to the ground is 0V, i check allmost all pins on secondary side and its all 0V, i only found 2V and 0.4V marked on picture.

[ben7]

Re: Dps-240fb

That small transformer is for the standby power supply.
On the high voltage side of it, there is a control chip under that small heatsink, and there is a capacitor right next to it (gold print on black plastic, Ltec brand). What is the voltage across that capacitor? It is C9x.. I can't see the rest of its part number because the silicone glue is on the pcb.

[rtstorm]

Re: Dps-240fb

That small transformer is for the standby power supply.
On the high voltage side of it, there is a control chip under that small heatsink, and there is a capacitor right next to it (gold print on black plastic, Ltec brand). What is the voltage across that capacitor? It is C9x.. I can't see the rest of its part number because the silicone glue is on the pcb.

Do you mean to connect the instrument directly to the capacitor or between ground and capacitors.

When i connect across capacitor there is 0V, but when measuring from ground and capacitor there is 84V

[ben7]

Re: Dps-240fb

Do you mean to connect the instrument directly to the capacitor or between ground and capacitors.

When i connect across capacitor there is 0V, but when measuring from ground and capacitor there is 84V

Across the capacitor.

What is the resistance across the capacitor?

[rtstorm]

Re: Dps-240fb

resistance is 8.5k Ohm

[ben7]

Re: Dps-240fb

resistance is 8.5k Ohm

Both ways?

[rtstorm]

Re: Dps-240fb

in other way is 4.3k Ohm

[ben7]

Re: Dps-240fb

in other way is 4.3k Ohm

Could you double check again, you are getting zero volts DC across that capacitor?

[rtstorm]

Re: Dps-240fb

yes, is is a 0V, actually it is 0.2V.

I did not connect wire green + ground), but if this is stand by 5V it does not matter.

[ben7]

Re: Dps-240fb

yes, is is a 0V, actually it is 0.2V.

I did not connect wire green + ground), but if this is stand by 5V it does not matter.

Yep this is the standby power.

Ok, can you please remove the small heatsink on that chip, and tell us the part number?

[rtstorm]

Re: Dps-240fb

it is:
J422
TNY268P
28276P

[ben7]

Re: Dps-240fb

it is:
J422
TNY268P
28276P

Ok, it is a TinySwitch smps controller, TNY268P.

What is the resistance across the capacitor, with the control chip removed from the board?

[rtstorm]

Re: Dps-240fb

when i remove controller resistance is 4.1k Ohm in one way and another is 9.2k Ohm i other way

[ben7]

Re: Dps-240fb

when i remove controller resistance is 4.1k Ohm in one way and another is 9.2k Ohm i other way

Try replacing the controller anyway, it still could be faulty.

[rtstorm]

Re: Dps-240fb

ok, i will try to find it in local store on Monday

[rtstorm]

Re: Dps-240fb

hi, i replace the controler and no luck. PSU do not work.

[rtstorm]

Re: Dps-240fb

I have 0.31V across capacitor C9x...

[ben7]

Re: Dps-240fb

Arrgh. Sorry about that. Fixing a PSU through a computer screen is tough xD

Try desoldering J37, and see if you get 5v standby.

[rtstorm]

Re: Dps-240fb

I know it is tough, thank you for your time.

I desolder the J37 (wire) and still the same. 0V on purple wire.