Samsung LN32A450C1D Red light

[CraigR]

Re: Samsung LN32A450C1D Red light

ICM856 from left to right looking at it 600mV, 1.1V, .9mV, 240mV, .9mV

[multimeter]

Re: Samsung LN32A450C1D Red light

vcc voltage isnt reaching the IC,what voltage are you getting on the large filter cap?

[CraigR]

Re: Samsung LN32A450C1D Red light

Starts at 384V then it drops to 164V then back up to 384V and drops repeating.

[budm]

Re: Samsung LN32A450C1D Red light

Is the PS_ON also swinging up and down?

[CraigR]

Re: Samsung LN32A450C1D Red light

I do not see PS_ON anyplace to check.

[budm]

Re: Samsung LN32A450C1D Red light

Schematic page 2, connector CNM802 PIN 1 (ON/OFF).

[multimeter]

Re: Samsung LN32A450C1D Red light

have you disconnected mainboard and re-tested voltages yet?,as budm pointed out in my opinion fluctuating voltage on the ps-on signal along with the filter cap could point to a mainboard fault.

disconnect it for testing

[CraigR]

Re: Samsung LN32A450C1D Red light

Yes! 3.7V then into the mV range back and forth.

[CraigR]

Re: Samsung LN32A450C1D Red light

So I should disconnect the mainboard and then check the filter cap again?

[tom66]

Re: Samsung LN32A450C1D Red light

Yes.
Completely misread your post, thought you had 12V but no 5.3V d'oh...

[CraigR]

Re: Samsung LN32A450C1D Red light

Disconnected the mainboard and 164V steady at the filter cap.

[multimeter]

Re: Samsung LN32A450C1D Red light

Disconnected the mainboard and 164V steady at the filter cap.

with main board disconnected,you can use a resistor in series 100 470 ohm,to jumper ps_on(on-off) to standby voltage,then check filter cap,should be around 380v,then check psu output voltages again.

if they are all there,you have a mainboard fault possibly

[CraigR]

Re: Samsung LN32A450C1D Red light

384.1V steady with that jumpered.

[tom66]

Re: Samsung LN32A450C1D Red light

What do the 5V, 12V/13V, 24V measure in this state?

[CraigR]

Re: Samsung LN32A450C1D Red light

With mainboard disconnected and it jumped I still get No other voltages.

[tom66]

Re: Samsung LN32A450C1D Red light

OK do you see the capacitors:
- CB806
- CP811
- CM807

on the primary side (HOT/LIVE section)

Please check the voltage across them (red probe on end, black probe the other - polarity not important.) Use 200VDC range.

Voltage for PFC IC could be high enough but still be too low for PWM IC, or PWM IC/Fuse/FETs are bad.

[multimeter]

Re: Samsung LN32A450C1D Red light

psu may not fire up until bl_on signal is present,not sure on the schematic where that stby voltage is,it will normally be on the same connector as the bl_on signal rail.POSSIBLY that through feedback protection circuit,it is not totally powering up the psu

[tom66]

Re: Samsung LN32A450C1D Red light

PSU should be completely on without BL ON, the BL ON just passes through to inverter board, like most LCD PSUs.

[CraigR]

Re: Samsung LN32A450C1D Red light

806=17.6v 811=14.65v 807=14.59v

[budm]

Re: Samsung LN32A450C1D Red light

This power supply is known for having bad capacitor CM808 (18nF 630V, blue rectangular cap) which is part of power transformer drive circuit for the 5V, 12V, and 24V. Check to see if it still has the correct capacitance and not bulging out to the side.