Need help with Samsung LN40E550f7f

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

All the specs seem the same except for the packaging type. I don't know anything about said components except what I'm learning.

I'm not sure, could call them and give m your part description number etc.

[budm]

Re: Need help with Samsung LN40E550f7f

I get 34.7vac

All measurement are done in V DC mode setting on the meter.

[Kindred1]

Re: Need help with Samsung LN40E550f7f

I knew I'd get that wrong. - 16.9 vdc

[Kindred1]

Re: Need help with Samsung LN40E550f7f

So is that voltage correct?

[budm]

Re: Need help with Samsung LN40E550f7f

I knew I'd get that wrong. - 16.9 vdc

You have (-) symbol in front of the reading, is that right?
If the Red probe is on the VCC pin 8 and the black probe is on GND pin 6 then it should not show as Negative reading on your meter, Please verify.

The minimum start up Voltage for this PFC IC is 12VDC (+/-1V).

[Kindred1]

Re: Need help with Samsung LN40E550f7f

No, that was a typo.

[budm]

Re: Need help with Samsung LN40E550f7f

That means the IC is getting the VCC to run so at this point I would get a couple ICs (buy more than one so you have spare in case it gets damaged during the soldering works) and replace it.
Line #5 (cut tape) on that Digikey will work.

[Kindred1]

Re: Need help with Samsung LN40E550f7f

Thanks! I will continue to read up on this stuff. Will post after repair.

[pocketwatch62]

Re: Need help with Samsung LN40E550f7f

Thanks! I will continue to read up on this stuff. Will post after repair.

Kinderd1,

Did you ever get this set going? I have the same set with the same problem.

Thanks

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

Not sure if you did the tests in this thread, try test on post #89, report results.

[pocketwatch62]

Re: Need help with Samsung LN40E550f7f

nomoresonys,

with the main board disconnected the backlights flash for just a split second.
I have all the low voltage, But i have only 167DCV on the main filters.

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

So it doesn't go above 167 when you hit power, should go to around 400 when you hit power, could be problem in pfc circuit.

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

Try heating the powerboard with a hairdryer small section at a time heat all the capacitors optos etc. see if tv comes on or changes any.

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

Test connector from mainboard to powerboard on powerboard side with all boards hooked up, test with tv plugged in but off then hit power, report both conditions here, give pin number, pin description/name and condition both off and when you hit power on.

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

Did you check all your diodes?

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

Look closely at CP804, any bulging or anything?

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

Maybe try unplug inverter/s from powerboard, see if your filter caps come up to proper voltage. (best practice is always unplug tv from outlet before unplug any cables etc. then plug tv back in outlet and try it)

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

As always, BE VERY CAREFUL when working on HOT/DEADLY side of powerboard lots of high voltage and the inverters can have more than 1000 volts coming out.

[budm]

Re: Need help with Samsung LN40E550f7f

Kinderd1,

Did you ever get this set going? I have the same set with the same problem.

Thanks

Please report what Voltages you have on the power supply connector's pins that goes to the Main board, put down pin number and follow by pin name and the Voltage reading when TV is plug in and when power switch is activated, that will be a starting point.
Also provide good clear pictures of YOUR boards.

[pocketwatch62]

Re: Need help with Samsung LN40E550f7f

nomoresonys,

The main filters comes up to 415 DCV for a split second the settles down to 159 DCV.
CP804 looks good but i know that don't mean nothing.
Do i need to remove it and check it?