SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

[steved271]

Good afternoon guys....

I have an issue with the above power board....

Powers on, Blinks 5 Times then powers off..... after reading up on other posts, i have tested the standby power and get 5.1 volts

I went back to measure the power of the Big Cap in the center of the board....

Before i switch on it gets 128/129 Volts
when powered on it fluctuates between 218/228 Volts..... From what i gather from other posts this should be up near 380 Volts....

Has anyone had any luck with fixing these PSU's or is this a mainboard issue...


I have the schematic and would really like to figure out which componants to look at and fix it.... so that i can then Advise others

[budm]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

What is the GND point for the meter you use for making the DCV measurement, it looks like you use the chassis.
What DCV do you get when measured right between the two legs of the main filter cap.
Pictures of YOUR board?

[steved271]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

I was using the chassis as Ground point.....

measuring across the points

in standby it measure 386V
When powered on it measures 351V

I am adding a pic of what i think is a fuse on the inverter board....

it is labelled 3A/63V and is white in color.... It has 24V In but 0V out... COuld it be that the Inverter board is goosed?


thank you for the quick reply

[budm]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

In standby the DCV should be around 330VDC, when PS-ON is received from the main baord then the DCV should be close to 400VDC, so so far you do have 24V so the power supply board is working.
Since you do have blown fuse on the inverter board then it have shorted power MOSFETs that drive the inverter transformer, so more troubleshooting on the inverter board will be required.
BTW, when you make the Voltage measurement in the DC Primary side you need to use the negative leg of the main filter cap as the GND ref. point for your meter, when you make the measurement on the cold side of the power supply, you can use the chassis as the GND ref. point for your meter.
What is the model of this SAMSUNG TV?

[steved271]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

Thank you for the Ground point advice, thats very helpful..


the model number is a LE32R88BDX/XEU

After further testing of the Inverter board, All the fuses are blown.... No continuity but 24V at input side and 0V at output side...

So i would guess that something has gone seriously bad on the inverter,

I can see around one of the Caps on the inverter board it looks like some brown crusty stuff around the solder point....

For the sake of the £1.55 it is going to cost for 10 new fuses, i am going to order them and test putting each individual one at a time and see which one blows it... all the cathode tubes plug into this seperatly so will unplug these to start with to isolate a bad tube causing it to blow fuses... if they all stay working after then i will plug the tubes in one by one to find the culprit...

as i am a hoarder and keep all my old cracked screens i may have some Tubes that i can replace with...

[vinceroger69]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

it could be a inverter transformer blowing the fuse whats the part number printed on them as we maybe able too get the pin out so you can run tests just too rule the transformers out.

[steved271]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

The Transformers are 4018L 0742LC ST5-4

how would i test those as all the fuses have blown and no 24V getting to them?

cheers for the help

[ReeceyBurger123]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

it could be a inverter transformer blowing the fuse whats the part number printed on them as we maybe able too get the pin out so you can run tests just too rule the transformers out.

Inv tarfos will normally never ever blow the protect fuses they are isolated separately with the feedback circuit and there is not much to go wrong with them unless they arch to the chassis which even then it would trip the protection and it wont send the Vcc drive to the fets

[ReeceyBurger123]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

I have the 42" of this inverter in atm also I have had a SSI400_14A01 inverter which has them same driver fets which commonly short and fail.

[vinceroger69]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

just test the resistance of each transformer no need to have power the readings you should get on each is in this link each transformer should measure about the same im not saying any of yours have gone but certainly worth ruling them out.
http://www.lcdparts.net/TransformerD...ProductID=3497

Edit just saw reece post as hes worked on many more sets than me maybe worth testing the driver fets then i will let reece explane how to test them if you need to know and cheers reece good information as always.

[ReeceyBurger123]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

No worries mate glad to help Also you need to check those little fets I have seen countless amounts of them fail due to heat.

[steved271]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

Reece, Thanks for the replies...

Finally got this figured out.... Just in case it helps anyone else...

This was a transformer on the inverter board that had failed..... I had an old Neon TV which uses the exact same screen and Inverter board which has a Power board issue... Its just doesnt power up(trying to figure out that issue)

When i Swapped the Inverter the set powered up and lit up perfectly to find a smashed screen... Dohhhhhh.... so i just swapped the screen from the Neon to the Samsung... Cant remember the Model number of the screen but will post back that later when i get home.....

Great Youtube vids by the way.... On a side note, have you ever had to fix a Blinking power supply on a Vestel 17IPS16-4 by any chance? if so any tips?

Regards

Steve

[budm]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

Thanks for the follow-up on the repair.

[steved271]

Re: SAMSUNG BN44-00191a Power Board Red Light 5 Blinks

No Worries budm, It frustrates me when there is no follow up because it could help so many people out.... I did one on AV Forums a few years ago with my philips 42" Plasma Monitor... Think it was a BDSV42 Something or other... asked for help and with minimal knowledge and very few people having this set, it took me over a year to keep going back to it...

Found it to be a Voltage regulator on the Standby Circuit that had gone bad.... Input was 5v and output was 1.2v when i looked at the datasheet it should been 1.8v out...