LITEON PS1211 power supply

[stj]

Re: LITEON PS1211 power supply

if you heated that area, i suspect the opamps (lm358?) or a zener diode.

[ktmmotocross]

Re: LITEON PS1211 power supply

if you heated that area, i suspect the opamps (lm358?) or a zener diode.

but how can i check it when it works after little heat.

i allready resolder allmost everything in that area.

u tnik that removing, take it to cool and measure it will find wat is bad?

that two is LM358NG as u wrote, how can i check it?

[stj]

Re: LITEON PS1211 power supply

there are devices to test op-amps - i have one.
there are ways to test zeners.

but unless your doing it a lot, it's simpler to just replace them and see if its fixed.
LM358 is used in so much stuff that i'm sure you can find some.

[R_J]

Re: LITEON PS1211 power supply

All that ic900 circuit does is to output a PG (Power Good) signal to the main board, you may have a problem with the optocoupler circuit or reference ic tl431, does changing the adjustment VR300 have any effect on the 12 volt output?
PC300a is for feedback regulation of the 12 volts, PC700a is for over voltage protection, if the 12 volts goes above 13 volts it turns on PC700a and shuts the 12 volt power supply (ic300) down
If PC700a (led) turns on, PC700b (photocell) conducts turning on Q701, taking ic300 pin #1 to ground, turning off the ic output.

So you should be able to operate the power supply without PC700, But you would NOT have 12 volt over voltage protection, so only operate this way monitering the 12 volt output but not connected to anything else. If it operates ok then it is that circuit that is causing the shutdown. If it still won't operate or shuts down your fault is elswhere