Samsung 245BW Not Powering Up

[SleightOfHand]

Hey guys, so my monitor has been a little whack for the past year or so, having issues with flashing screens, unresponsive buttons, and issues turning on when "cold," but after leaving my PC alone for a few days, I think it finally took its last breath. Searching online makes it look like the capacitors are usually to blame as well as some of the resistors, and when opening up the power board, I noticed that the largest capacitor had some plastic broken on top of it, which I suppose means it is bulged and probably the culprit. I don't have a soldering iron or multimeter (which I will be purchasing tomorrow), but I wanted to post here to see if you guys see anything else that might be an issue. Thanks for the help!

[Morsus]

Re: Samsung 245BW Not Powering Up

Well yeah, the big capacitor would be the problem probably. I would also check if top right two capacitors on the first picture are bad and the bottom left mosfet/diodes (the ones screwed in the heatsink) for corrosion or they are just dirty. In any case you will need a soldering iron or a friend with it if you want this fixed under minimal price.

[1supertech]

Re: Samsung 245BW Not Powering Up

Clean brown gunk off which is glue that became conductive when turns brown replace three resistors near serial number. replace all capacitors

[budm]

Re: Samsung 245BW Not Powering Up

Yep, remove ALL the glues and check those three 68 Ohms resistors covered with glue next the BN44-00173A label.
There are many threads about this 'BN44-00173A' also in this forum.

[SleightOfHand]

Re: Samsung 245BW Not Powering Up

Thanks for the tips guys. Im trying to find a new 82uF 450V capacitor, but I guess it's a bit of a specialty item, so it's going to be a couple days till I am able to get one on my hands. In the mean time, I have cleaned the glue and will be replacing the resistors, so perhaps I won't have to replace the capacitor (even though it clearly looks like it has blown).

[re-atari]

Re: Samsung 245BW Not Powering Up

Clean brown gunk off which is glue that became conductive when turns brown replace three resistors near serial number. replace all capacitors

+1

What do you mean by 'not powering up'? Does the blue PWR light turn on solid when switching on the monitor, do you just get a black screen?

This brown glue is a real plague. It chars up and gets conductive and corrosive in the process. Chances are when removing it you will find the resistors' connecting wires are pitted with green corrosion.

In my experience, on a defective 245B with a 173A PSU where the PWR light shines solid after switching on, only RB805 (68R) is failing. In every 245B I fixed (8 so far) this resistor showed open (infinite resistance). It is the utmost right one of the row of three resistors along the bottom edge on your 2nd foto. RB806 and RB807 usually are OK. I replace them all three just for good measure, but take 3W types. The cost is minimal (below $1 a piece).

On every 173A board I fixed, RB801 (100k, below the transformer in the middle of the board) and RP820 (47R, near the heatsink on the bottom left) were also covered in this brown gunk, and just as corroded. I replace them as well.

I haven't had to replace the caps on any 245B yet. Your foto's show that on your PSU (at least) the 450V one has failed. I haven't seen this yet. Curious what could have caused it. Chances are there is another failed component on your board, which caused the 450V cap to blow its top. Might just be the glue, might be something else. I'd start with replacing the resistors and HV cap, shouldn't cost you an arm and a leg.

On the bright side: you're lucky your 245B has a 173A PSU. 245B Plus monitors have a 195A PSU, which are very much more difficult to fix.

re-atari

[SleightOfHand]

Re: Samsung 245BW Not Powering Up

+1

What do you mean by 'not powering up'? Does the blue PWR light turn on solid when switching on the monitor, do you just get a black screen?

This brown glue is a real plague. It chars up and gets conductive and corrosive in the process. Chances are when removing it you will find the resistors' connecting wires are pitted with green corrosion.

In my experience, on a defective 245B with a 173A PSU where the PWR light shines solid after switching on, only RB805 (68R) is failing. In every 245B I fixed (8 so far) this resistor showed open (infinite resistance). It is the utmost right one of the row of three resistors along the bottom edge on your 2nd foto. RB806 and RB807 usually are OK. I replace them all three just for good measure, but take 3W types. The cost is minimal (below $1 a piece).

On every 173A board I fixed, RB801 (100k, below the transformer in the middle of the board) and RP820 (47R, near the heatsink on the bottom left) were also covered in this brown gunk, and just as corroded. I replace them as well.

I haven't had to replace the caps on any 245B yet. Your foto's show that on your PSU (at least) the 450V one has failed. I haven't seen this yet. Curious what could have caused it. Chances are there is another failed component on your board, which caused the 450V cap to blow its top. Might just be the glue, might be something else. I'd start with replacing the resistors and HV cap, shouldn't cost you an arm and a leg.

On the bright side: you're lucky your 245B has a 173A PSU. 245B Plus monitors have a 195A PSU, which are very much more difficult to fix.

re-atari

Hey Re-Atari, thanks for the tips. When first posting, the blue power light wasn't even turning on, but after removing the glue and reconnecting the power, the monitor returned to it's flashing state that it used to be in before the ultimate failure. Prior to this failure, what would often happen is that if I keep the monitor off for more than a few days, when turning it back on, the monitor would flash for a while (30 min or so) until the flashing would just kind of stop and return to normal behavior.

The local radio shack and other electronics stores nearby did not have a replacement for the 450V capacitor, so I ordered it online, which would take nearly a week to come in, so I'm just playing the waiting game right now. I noticed in the picture of the replacement cap that I ordered that it looks smaller than the one on the power board, but the specs appear to be the same. https://www.amazon.com/United-KXG-45.../dp/B00N87DBNK. The main thing I'm unsure about is that the material is not specified. Will this capacitor work ok?

[re-atari]

Re: Samsung 245BW Not Powering Up

When first posting, the blue power light wasn't even turning on, but after removing the glue and reconnecting the power, the monitor returned to it's flashing state that it used to be in before the ultimate failure. Prior to this failure, what would often happen is that if I keep the monitor off for more than a few days, when turning it back on, the monitor would flash for a while (30 min or so) until the flashing would just kind of stop and return to normal behavior.

The flashing was probably caused by the failing HV cap. Usually the effect of a failing cap reduces when it heats up, which is what happens when the monitor is switched on for some time. A good way to test a suspicious cap is blowing hot air on it with a hair drier or a paint remover gun. Your cap looks too far gone for this test, though.

The local radio shack and other electronics stores nearby did not have a replacement for the 450V capacitor, so I ordered it online, which would take nearly a week to come in, so I'm just playing the waiting game right now. I noticed in the picture of the replacement cap that I ordered that it looks smaller than the one on the power board, but the specs appear to be the same. https://www.amazon.com/United-KXG-45.../dp/B00N87DBNK. The main thing I'm unsure about is that the material is not specified. Will this capacitor work ok?

Looks like it will, but it looks taller than the original one. Check the height before and after soldering it in place and when mounting the PSU on the mounting plate. The top of the cap has to be clear from the mounting plate by several millimeters. Might be a good idea to put some electric insulation to the mounting plate, just to be on the safe side. Duct tape?
I don't know if the sellers on Amazon stock genuine caps or Chinese fakes, though. Ebay is littered with fakes, no chance of getting originals there. From what I've heard in the media, lately Amazon is plagued with fake webshops, and does just about nothing to get these scammers from their network.
Mouser, Digikey and Farnell are reliable electronics webshops, but may carry minimum order amounts ($25 or thereabouts). I never needed to order from them yet, as there's a well-stocked electronics shop in my home town. I can get every component I need there, or they order it for me.
BTW, that's an expensive cap. I'm glad that up to now I never had to replace this particular one in the 245B's I fixed.

re-atari

[stj]

Re: Samsung 245BW Not Powering Up

the cap in the board foto is a low profile snap-in cap with 10mm lead pitch.
i doubt the amazon one will fit.

[re-atari]

Re: Samsung 245BW Not Powering Up

the cap in the board foto is a low profile snap-in cap with 10mm lead pitch.
i doubt the amazon one will fit.

You're right, overlooked this on the linked page. The webshop lists the size of the cap: height is 35.5 mm (1.397") and lead spacing 7.5 mm (0.295"). Looks like the cap is too high to fit properly. The different lead spacing requires some bending and twisting the leads to make them fit the holes in the PCB, which makes the cap need an additional few millimeters of height clearance.

Maybe the cap can be fitted axially (i.e. 'laying on its side') temporarily for testing purposes, with the leads bent at a 90 degree angle to fit in the soldering holes. Not my preferred solution, esp. not in the long term, I must add, as the top of the cap wil stick out sideways from under the PCB. The top will be very close to the side of the mounting plate, which poses a risk of arcing. There may even not be enough room to fit the cap like that in the first place. But with proper insulation it would do for the time being just to check if replacing this cap and the resistors mentioned earlier on will bring the monitor back to life.

Addition to original post: The Samwha cap has a height of 21 millimeter and a diameter of 30 millimeter. Checking the Mouser website, it looks like this one is a direct replacement:
http://www2.mouser.com/ProductDetail.../861111485022/

This one is slightly higher (26 millimeter), but may fit as well:
http://www2.mouser.com/ProductDetail.../861021485019/

They are quite a bit cheaper than the Amazon one. Do check out if Mouser has a minimum order amount and if so, how much it is.

re-atari

[SleightOfHand]

Re: Samsung 245BW Not Powering Up

Thanks guys, you are awesome! Measuring the cap on the power board looks like the first link is a perfect fit, so I picked it up and it will be shipping today! FYI there was no minimum order required for Mouser.

[re-atari]

Re: Samsung 245BW Not Powering Up

Thanks guys, you are awesome! Measuring the cap on the power board looks like the first link is a perfect fit, so I picked it up and it will be shipping today! FYI there was no minimum order required for Mouser.

That's good to hear, minimum orders can be a real pitfall. With a bit of luck you may be able to cancel your order with the Amazon webshop.
If all goes well, i.e. speedy delivery and no other malfunctioning components, who knows, you could have your monitor up and running again by the weekend.

re-atari

[IU5ICI]

Re: Samsung 245BW Not Powering Up

Hi all, i have a similar problem with a 245B+ with board BN44-00173A.
The monitor turns on but i don't have backlight.
+24V is missing (is present without load but with just 200ma load it drops to 9v).

If i brutally connect an external 24v power supply directly on the 24v rail, it all works fine (no short, nothing getting hot, etc)

I've already replaced the 3 resistors but i still have to replace caps.
Can it be a bad caps related problem?
Does anyone have a full cap list ?

Thank you for the help.

[budm]

Re: Samsung 245BW Not Powering Up

Check the capacitance (test it off the board) of the coupling/dc blocking cap CM802.

[IU5ICI]

Re: Samsung 245BW Not Powering Up

Check the capacitance (test it off the board) of the coupling/dc blocking cap CM802.

It's 78ohm with 1.2ohm ESR

[budm]

Re: Samsung 245BW Not Powering Up

It's 78ohm with 1.2ohm ESR

78 Ohms? What is that?

I am asking you to check the CAPACITANCE of the cap OFF the board.

[IU5ICI]

Re: Samsung 245BW Not Powering Up

78 Ohms? What is that?

I am asking you to check the CAPACITANCE of the cap OFF the board.

I mean 78uf..sorry. Lapsus
I was checking resistors.

[budm]

Re: Samsung 245BW Not Powering Up

No way that blue cap is 78 uF.
It is 18nF (0.018uF) 630V POLYSTYRENE.
https://www.badcaps.net/forum/attach...9&d=1484177532

[IU5ICI]

Re: Samsung 245BW Not Powering Up

Ok today I'm dumb. I measured cp803.
CM802 it's fine (17.16nf)

[sdouze]

Re: Samsung 245BW Not Powering Up

Hello I have the same board. All of a sudden I heard a zap and I lost signal on the screen but the power led was steady on.I remove the psu board and I saw RM801 burned.I change the resistor and some other components that there values was out of specs.I turned on the power and again the rm801 blow up(as I expected) and my breaker tripped. Any ideas?

I found cm802 1.4nf instead 18nF(I have not change it yet)
rb806 80ohms instead 68ohm(i change them all)
and some RB801(was under glue) seems open (also not changed)