Samsung LE32R88BD/ BN44-00155A

[bornintheuk]

Hi All,

Safety resistor RM801 burnt out on switch on. Apart from that no visible distress on any other components on power board or inverter board.
Replaced this and Mosfets QM801, QM802 (FQPF9N50C), with more hope than conviction. Checked all diodes in situ and they appear fine.

Powered up initially without mainboard, inverter or backlight connected. After connecting these items in sequence, TV worked as normal. I probably turned TV on and off about half a dozen times over the next 3 hours and everything was ok. However, next morning, on switch, another crack and burnt out RM801.

It appears a surge is knocking out RM801. Any suggestions welcome.

Electronic knowledge about 30 years out of date.

[retiredcaps]

This is why we always ask for clear focused pictures which you have nicely provided. You have at least one, possibly more, bloated capacitor. The obvious one (a 10V) is the to the right of BN44-00192A.

Capacitors die from age, heat, and shoddy build quality. Capacitors DO NOT have to be visibly bloated in order to bad. They can be out of tolerance uF (a 1000uF measures 20uF) and/or have high ESR (ohm). A multimeter will be insufficient to test for ESR. For that you need an ESR tester which costs between $50 and $300.

Also, some of the glue has turned brown and could be causing a problem.

[Dgtech]

That resistor being a higher wattage resistor (maybe half watt), is taking on way more than it needs to. This one may be straight forward when viewing a schematic.

You should be able to find the schematic here:

http://elektrotanya.com

Just pop in your model number and it will allow you to download two per service manuals per day.

[bornintheuk]

Take a pat on the back Mr retiredcaps.
Your observations appear to be correct in a round about way.

When you referred to BN44-00192A (instead of BN44-00155A)
I was puzzled and assumed you had got some threads crossed and took little notice of your comments.

I can know see I had posted the wrong image (of a BN44-00192A),
which I must have downloaded in my research. The two boards look remarkable similar, (maybe just a different Europe/ US designation}.

The point is, I decided to check the board again visually. I noticed a faint black line on the circuit board where the yellow adhesive fixes blue capacitor CM810,(44nf 1KV) to it.I figured that if this was some sort of leaky conduction path across the capacitor lead out wires it was capable of passing enough current to blow safety resistor RM801.

After chopping away a the adhesive and removing the capacitor I scraped away the (carbonated?) black line, (track). With capacitor reinstalled and a new resistor in place, TV was back in business. It's still early days yet, (two), but as the theory appears sound, I am quietly confident.

As an extra precaution, I have removed adhesive from around other components where a leaky path could develop.

Attachments show actual board BN44-155A and problem area before and after capacitor removal.

[retiredcaps]

Originally Posted by bornintheuk

When you referred to BN44-00192A (instead of BN44-00155A)
I was puzzled and assumed you had got some threads crossed and took little notice of your comments.

It wouldn't be the first time. When helping multiple people, it is easy to get confused.

After chopping away a the adhesive and removing the capacitor I scraped away the (carbonated?) black line, (track). With capacitor reinstalled and a new resistor in place, TV was back in business. It's still early days yet, (two), but as the theory appears sound, I am quietly confident.

Please report back in another few days. I'm sure people are curious if that is the root cause and it may help others in the future.

[tsilis65]

Hi all from tsilis65 nafpaktos greece

[mickash]

Hi,

This is my first posting here.

I have also got a problem with brown glue and tracking around RM801 and CM810 on a BN44000155A PSU board fitted to a Samsung LE32R87BD.

There have been similar problems with this type of glue for many years. It breaks down with heat and becomes conductive, with obvious problems in cases like this.

Surely the manufacturers know about the problems with this glue, why do they insist on still using it? I can't even see why these components need to be glued in in any case.

I will remove this glue and scrape off any carbonisation of the board and replace the resistor, there is also a blown electrolytic cap which will also need replacing.

I will report back with the results.


Michael.

[aljef]

Thank you, I too have such problems. You really helped me.

[shokat]

i got power supply board no.bn44-00155a. problem are stand by light flashing.please which i replace.there no any visible swollen caps.

[selldoor]

What have you replaced?
Welcome to the forum-
We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed
http://www.badcaps.net/forum/attachm...1&d=1290283049

http://www.badcaps.net/forum/attachm...7&d=1280167246

It will be useful if you can say what the supposed fault was and a bit about yourself - skills tools etc. Do you have a multimeter and Soldering equipment and can you use them

[multimeter]

what does the "rm" stand for next to the resistor,i know the "r"is resistor,whats the "m" for?,im working on a bn44-xxxxxxxx supply a the moment and wondering what it stands for

[budm]

Can we see the picture of that 'RM'?

[selldoor]

I dont know but I dont think it will be significant Unlike FR= fusible resistor
my suggestion would be it relates to which board they are on. If you look at the other components there are CMxxx - cap and DMxxx - diode.

[multimeter]

Originally Posted by selldoor

I dont know but I dont think it will be significant Unlike FR= fusible resistor
my suggestion would be it relates to which board they are on. If you look at the other components there are CMxxx - cap and DMxxx - diode.

all the bn44-xxxxx boards seem to have the prefix "rm" next to the resistors,one of lifes little mysterys!

[multimeter]

Originally Posted by budm

Can we see the picture of that 'RM'?

thats the same "rm" resistor in my other thread on the samsung bn44-xxx thread,that was showing nearly dead short /low ohm reading lol,which i thought was a fusable resistor but no "fr" next to it

[shokat]

Originally Posted by selldoor

What have you replaced?
Welcome to the forum-
We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed
http://www.badcaps.net/forum/attachm...1&d=1290283049

http://www.badcaps.net/forum/attachm...7&d=1280167246

It will be useful if you can say what the supposed fault was and a bit about yourself - skills tools etc. Do you have a multimeter and Soldering equipment and can you use them

I have attached the images, and the fault is that the standby light keeps flashing.and I have got all the equipment as I am a bench engineer

[selldoor]

I dont know if its the change in weather but UK is producing the worst photos I have seen or rather cant see, for weeks- Have you looked at your photos. The idea is we look at them for suspect faults or known weak components then ask you to test them. Please practice with your camera and try for better ones. Looks like its too dark today in Bolton if its anything like here so wait for a bright day and take them outside if you cant get decent light near a window.

You also need to be more descriptive - we cant see what its doing. Standby light flashing tells us very little.
OK you will probably have to wait until you get the pics then put the set together unless you can remember : When you first plug the set in what does it do if anything
Does the standby light come on then and start flashing straight away? what colour is it Does it continue to flash for say 5 minutes? Does it flash a sequence - long flash- gaps or just flash the same rate whatever.
Were there any sounds - clicks - hissing -humming.
When you press the power on does anything change - if you used the remote control,try using the buttons and visa versa - anything change.

Can you switch it off with buttons or remote control?

During any of this did the screen flash.
If you switch it on in a darkened room does the screen glow at all.

Any burning smell?

EDIT - Was the set yours did it have any fault symptoms prior to not working - hard to switch on
screen flash , go dim, etc

[shokat]

thanks .there is no burning smell.no swollen caps.when i put my multi meter on s/by voltage pin.voltage are jumping 150 to 245 dc.always keep runing.
when you your finger to check like any component are warm.all secondery side are cold.

thanks

[F6CTW]

Hello,

I think I should give a big hug to Bornintheuk and Retiredcaps:

I had a dead Samsung LE26R88BD (red stand by led flashing but no power on) with a BN44-00155A board to repare.

When first looked at the BN44-00155A board I was very happy because I saw a bloated cap (2200µ 10V).

I changed all of the 13 caps on the board but still not working....

Then I fall on your thread and the desciption of Bornintheuk's story.

I checked the safety resistor RM801: blown and capacitor CM810: carbonated track between the two legs.

After changing RM801 and cleaning all the carbonared tracks and removing all of this damned brown glue the TV started working again.

Thank you very much again, you helped me a lot and I will think about you when I drink a round of first quality beer that the owner of the TV will offer me in reward!!!

[budm]

Great job.
When you see those yellow glue (it turns brown and become conductive and also will eat away copper traces), remove them ASAP.