Need help with Samsung LN40E550f7f

[Kindred1]

Re: Need help with Samsung LN40E550f7f

Is the ON = 169.2V reading with PS-ON present? If PS-ON present then we have problem with the PFC circuit. But I thought you have 365V on the fuse next to the filter cap before in the earlier thread, that must have been an error then.

O.K. What I have is : 164.5 vdc with power on. 168.3 vdc on standby.

361 vac with power on, 370 vac on standby.

[budm]

Re: Need help with Samsung LN40E550f7f

The readings in AC mode are just error of you meter.
Try measuring your car battery in AC Volt mode to see what you get, it will show high reading. Your meter probably has simple half-wave rectifier in the AC input circuit of the meter feeding resistor networks for the meter scale.
Any way, you will need to fix the PFC circuit at this point.
Real AC Voltage of over 300VAC on that electrolytics cap would have blown the cap by now.
https://www.badcaps.net/forum/attach...6&d=1519521712
Check the RESISTANCE of the PFC diodes in both directions to see how many Ohms they will show.

[Kindred1]

Re: Need help with Samsung LN40E550f7f

The readings in AC mode are just error of you meter.
Try measuring your car battery in AC mode to see what you get.
Any way, you will need to fix the PFC circuit at this point.
Real AC Voltage of over 300VAC on that electrolytics cap would have blown the cap by now.
https://www.badcaps.net/forum/attach...6&d=1519521712
Check the RESISTANCE of the PFC diodes in both directions to see how many Ohms they will show.

Yes. Hence my comment to you regarding me misunderstanding and screwing up. Apparently headaches/neckaches effect brain function. Anyway, I will do that first thing tomorrow and post my results. Thanks!

[budm]

Re: Need help with Samsung LN40E550f7f

At this point it is safe to say that you do have problem in that power supply/inverter driver board, you have all the correct command Voltages and other low switched Voltages but do not have the boosted Voltage to run the inverter driver circuits, we are getting there.

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

http://en-us.fluke.com/training/trai...ultimeter.html I believe you said your meter wasnt working in diode mode, this shows how to check diode in ohm mode, if you get ol in both directions try setting meter at 2000 ohm, often you get inaccurate measurement results when left in circuit. Diode should read ol in one direction, reverse meter leads and should get a reading.

[Kindred1]

Re: Need help with Samsung LN40E550f7f

Ok guys. I got my meter working properly. SO, in diode mode DP810 and DP802 both read .6v in diode mode - OL in reverse as it should I believe. However in Ohm mode I get OL both directions no matter what setting it's at. I have tested other circuits to verify ohm mode is working.

[budm]

Re: Need help with Samsung LN40E550f7f

OK, then we need to look deeper in the PFC circuit section, need to get the P/N of the PFC Controller IC so we can look up the spec sheet to locate the VCC pin to see if it is getting the switched VCC for the PFC IC to run or not.
PFC IC has designator as ICP801.

Repair kit:http://www.shopjimmy.com/samsung-bn4...repair-kit.htm

[Kindred1]

Re: Need help with Samsung LN40E550f7f

Ok, I found it. - It appears to have a little corrosion/heat damage on the top. ( no scorching on or around.) All I can make out is as follows.
B7E
AN
7930B

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

Ok guys. I got my meter working properly. SO, in diode mode DP810 and DP802 both read .6v in diode mode - OL in reverse as it should I believe. However in Ohm mode I get OL both directions no matter what setting it's at. I have tested other circuits to verify ohm mode is working.

Sometimes you will get an error reading when testing in circuit.

[budm]

Re: Need help with Samsung LN40E550f7f

FAN7930B
https://cdn.badcaps-static.com/pdfs/...0db2152410.pdf
Pin 8 is VCC, Pin 6 is GND which is connected to circuit GND (negative leg of the main filter cap) of the hot side, so be real careful since you are making measurement in the HOT DEADLY side of the circuit; I suggest you to at the least plug the TV into the GFCI outlet to protect yourself.

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

https://www.digikey.com/products/en?...G&pkeyword=&v=
Is this it?

[Kindred1]

Re: Need help with Samsung LN40E550f7f

FAN7930B
https://cdn.badcaps-static.com/pdfs/...0db2152410.pdf
Pin 8 is VCC, Pin 6 is GND which is connected to circuit GND (negative leg of the main filter cap) of the hot side, so be real careful since you are making measurement in the HOT DEADLY side of the circuit; I suggest you to at the least plug the TV into the GFCI outlet to protect yourself.

I get 34.7vac

[Kindred1]

Re: Need help with Samsung LN40E550f7f

https://www.digikey.com/products/en?...G&pkeyword=&v=
Is this it?

My antivirus blocks that page.

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

My antivirus blocks that page.

lol, thats digikey theyre known worlwide, definitely not a nefarious site.

[Kindred1]

Re: Need help with Samsung LN40E550f7f

lol, thats digikey theyre known worlwide, definitely not a nefarious site.

I think it's just their certificate. Heading there now.

[Kindred1]

Re: Need help with Samsung LN40E550f7f

the 4th one is.

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

You could exclude them in your antivirus, as in white list, lets the antivirus know that this site is ok.

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

the 4th one is.

Ok, make sure, I think digikey has more reasonable shipping costs than mouser.

[nomoresonys]

Re: Need help with Samsung LN40E550f7f

Will 5 or 6 work, not sure but I think 4 says minimum purchase is 2500, you could call and ask tho.

[Kindred1]

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.