Samsung 24" power supply BN44-00195A first stage voltage?

[Meerix]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

The Thread is about another Power Supply Board, the BN44-00175A.
My Board BN44-00169A has 3 resistors below the big cap. One i can identify (RB808) has only 2 Ohm (Red/Black/Gold/Gold) and another could be 100kOhm (Braun/Black/Yellow/Gold).
Tomorow i will try to clean. I am not sure i have these alcohol. I hope it will work

[selldoor]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Ok - sorry - there are many references to your board within that thread
but yes yours does not have the 3 resistors. It is a BN44-00195A
Not sure where you got .......169A - perhaps one of the other boards.

[Meerix]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Hi,

please excuse my late reply. In this week I bought the alcohol in a pharmacy. Yesterday I've tried to clean the components better. Even so it is not so easy.
I have a transistor (QB801) unsoldered which was full of this adhesive.

I do not know if I made him when desolder broken or it was already broken. Anyway, I've tested it according to these instructions Click (sry in german) and therefore the base-emitter is high impedance and thus the transitor is defective. The Part Number is D526-Y.
In Germany I have not found a way to order one. Perhaps there is an alternative that I can take. Does anyone knows an alternative or a shop where I can order it?
Did this transistor anything to do with controlling the backlight?
Slowly, I'm desperate.

[Rtech]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Suggest the full number is 2SD526Y,and these are usually available

[budm]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

@meerix, what DC voltage do you have on that main 450vdc main filter cap when the monitor is plugged in but not turn on yet, then when the power switch is activated?

[Meerix]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Currently I am still looking for a replacement for the transistor. Unfortunately, I can measure something at the power supply again. So far I have not found a German shop who want to sale me this transistor

[budm]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

This is the spec sheet for the transistor:

Higher rating will be OK.
This transistor supply the regulated B+ for running the PFC IC and SMPS IC.

[Meerix]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Hi,

i found this on ebay. It's in UK but ship to germany. Perhaps i will order some more parts (Mosfets FQPF5N50C, IC MC33067) there because to save the shipping costs.

[Meerix]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Hi,

after I couldn't get any compensation from the alleged defective transistor, I have soldered it again. I was amazed when I was able to measure the 24V to the inverter. A few times I made on / off. Every time the 24 volts were there. Then I did connected it again to the panel and had a picture immediately. Apparently, to clean it has helped. The transistor test, I probably misinterpreted.

I'll be watching it today and tomorrow, before I finally build it back together. I hope it stays that way. Thank you again.

Greetings from Germany

[budm]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Glad to hear it working, that transistor supplyies the voltage to run the PFC and the 24V power supply section, so if the 24V went away again, now you know where to check.

[sky007]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Need help here.

Got a monitor from my friend. Power supply is BN44-00195A. It gets 2 fuse blown, NT801S blown as well. After some work, cleared up all bad glue, found QP801S blown as well, replaced QP801S. I do not know what NT801S is, just found one NTC thermistors from a old computer power supply. Now connect all the boards together, I can see the blue power LED blinking, but I can't turn it on. Measure the main board connect, only SB give the 5.2V. Checked PFC, it is 155V only.

What else should I check? Thanks.

[PatK]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

I've got a Samsung 2493HM that didn't power up the other day, just sizzlepop and nothing. It's got the BN44-00 195A power board. I'm visually challenged these days, no obvious sings of cap bulging, one blow fuse at position FP04 (centre behind the power plug) I could replace the bigger cap or two, but isn't there someplace I could just buy a brand new power supply, or is this beyond the budget for something like this?

I'm a pensioner but in my younger days, this would have been easy, but now they claim I'm legally blind, and this kind of job is a bit beyond.

[Toasty]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Welcome!

Inexpensive and reliable - ShopJimmy.com - but they're out of stock.

Here's an article that I used and liked:
http://blog.whitesites.com/How-to-Fi...97265_blog.htm

You best bet is probably ebay, but be warned that you may be buying a used item. You could be back in the same boat 6 hours/days/months from installation.

I've never used these folks, but their price seems fair:
http://www.iccfl.com/product_info.php?products_id=11238

Again, possibly a used product.

Ebay has some China boards. Unknown if new or just cleaned up to look that way.

Perhaps a kind soul nearby you who could do the work with the correct parts...?

Best of luck!
T

[PatK]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Side note for Canadians 'Creatron Inc in Toronto sold me the entire 'kit' of caps and the one bad fuse I had for $7.20+ tax

[Toasty]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Okay... but, who's caps? What brand(s)? What series?

The pic they have of their choices is Chang, which is Huawei.

STANDARD electrolytics will not work properly. MUST be low ESR.

T

[only]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Hello, this forum has helped me a lot in debugging.

I also have a BN44-00195A PSU in my Samsung Syncmaster 245B.
For me, however, the error was another.
For me, the transformer TM802 has been destroyed by the bad glue. Thus, the FETs QM801, QM802 and resistance RM801 have been destroyed.
As a replacement for the FETs I used the type IRF840A.
And to replace the transmitter TM802 I used by Würth Elektronik the transformer 749196301. It must always be connected in series two coils. This one again has 3 coils. It has to be absolutely paid attention to the correct polarity (points in the diagram).
For the resistor RM801 I took a normal 0.22 Ohm and 0.6 watts.

The monitor is now working properly again.

Translated with Google Translator German to English.

[davethompson]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Hi team, I have no wish to hijack a thread but it seems I have no permissions to do anything but reply to a post, even after following the rules and creating an introduction post. If the mods want to move this, then so be it.

I too have a monitor with this power supply fitted. It is a Samsung Synchmaster 2493hm. This monitor exhibits the typical bad caps symptoms and was abandoned here after I supplied the owner with a new monitor. Since it is an good quality monitor, I thought I'd go the extras mile and try to repair it.

The symptoms are as follows: 50% of the time the monitor will run with no problems, and the picture is clear and crisp with plenty of brightness and contrast left in the controls. The front-panel touch functions work perfectly, as does the built-in audio. In times like this you'd never think there was anything wrong with it. However, the other 50% of the time, and this is completely random, that is, not seemingly affected by temperature, vibrations etc, it will not display an image.

The blue 'active' light comes on to show a signal has been auto-detected - and the auto-input detect system works as expected - but the display remains completely black; the monitor does not display either any of the on-board menus, nor any signal input. Often this blank display is accompanied by an electrical-sounding noise (but not always) that defies description, other than to say it sounds like a pig's squeal, quite loud and initially very startling. It is a raucous tone, quite grating but short lived (I'd estimate about half a second). The picture does not come on or go out in conjunction with the noise, and the noise happens only sometimes, (always when the monitor is switched on and the blue signal light active), but only when the picture is not present. It never happens when the image is displayed.

I cannot say with 100% certainty that the sound doesn't come from the built-in speakers, but I don't think it does; it sounds more to me like an electrically-generated squeal that emits from the area of the circuit boards, midway in the rear of the monitor as opposed to out of the speakers at the front. Like I say, I assumed the problem was caps and after having repaired dozens of monitors over the years, stripped this one down expecting it to be an obvious popped cap problem.

However, I can see no obvious issues with the boards. They all look clean as a whistle. I have a microscope and there are no cracks or otherwise damaged parts that I can see. I have followed this thread (and others featuring Synchmaster monitors) and have tried the various suggestions such as cleaning potentially-conductive old glues and things but to no avail, hence my call for help here.

Has anyone come across anything like this before, or have any further suggestions? I could just start replacing caps, then diodes and FETs but I'd rather be a bit more targeted if possible. The central large cap in the middle of the power supply board looks fine, as do all the others. The 'logic' board (for lack of a better term) has solid caps and all of those look good as well; instinct tells me this is a power problem but of course my instinct could be way off the mark.

Thanks in advance and if anyone wants some pictures (though my power supply board is no different than the ones mentioned here, not that I can view any attachments as I don't have permissions, but the part numbers are the same) then I'm happy to provide them.

Cheers, Dave.

[Agent24]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

If you did post an introduction already I don't know why you aren't able to start your own thread, that seems rather odd! In any case, I've noticed that people don't seem to mind posting in the same thread too much as long as it's about the same device.
But since this thread is just about a power supply rather than a specific monitor, it's probably best if you contact a moderator and find out why you can't start your own... you're likely to get more help with your own thread anyway.


Two things that spring to mind about the no picture fault though:

When you get no image, do you get no backlights as well?
If so, have you tried the bright light trick to check for a picture on the LCD?

Have you tried comparing voltages\control signals at the power supply and voltages of any secondary regulators on the logic board for any change between the working and non-working states?


For the noise itself... you could try to narrow down the source of the noise with the old cardboard tube trick but if it only happens for a split-second I suppose that would be rather difficult. I guess you could at least eliminate or prove if it's the speakers by disconnecting them.

As far as I know, squealing noises can come from overloaded power supplies, so it's possible something is intermittently shorted or otherwise drawing too much current, or if for some other reason the supply is not running normally. (like a faulty feedback loop).

[davethompson]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Two things that spring to mind about the no picture fault though:

When you get no image, do you get no backlights as well?
If so, have you tried the bright light trick to check for a picture on the LCD?

Have you tried comparing voltages\control signals at the power supply and voltages of any secondary regulators on the logic board for any change between the working and non-working states?


For the noise itself... you could try to narrow down the source of the noise with the old cardboard tube trick but if it only happens for a split-second I suppose that would be rather difficult. I guess you could at least eliminate or prove if it's the speakers by disconnecting them.

As far as I know, squealing noises can come from overloaded power supplies, so it's possible something is intermittently shorted or otherwise drawing too much current, or if for some other reason the supply is not running normally. (like a faulty feedback loop).

Thanks for that advice. The sound definitely comes from 'inside' the monitor, not the speakers, and it falls in pitch, almost like something discharging quickly but violently. The image is definitely not there and there is no back-lighting present. Then only way I know the monitor is 'online' is due to the indicator light changing to blue when a signal is detected. Also, the audio side works as expected when powered on and using HDMI or audio in so while that side of it is fine, the screen is dark (completely).

What surprises me is that half the time it works perfectly, with no artifacts, lines, flickering or anything else to indicate there is anything electronically wrong, until it just 'goes dark'. It is also co0mpletely random, which I hinted to in my post, but I cannot 'trigger' it to fail, nor can I ascertain any link between temperature and operation. One morning it will work, another it wont. Vibration on the boards has no affect, nor does squirting cold air or otherwise onto components. Got me beaten! I've a good mind to just forget it but it seems a crying shame as it is otherwise a very nice monitor. However, given a replacement from my suppliers costs a couple of hundred bucks it makes no economic sense to waste too much of my time on it.

Thanks again and all the best.

PS. I think I might have tried logging in too quickly after making that initial intro post to make another topic. I'll give it another shot today.

[Poca44]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Hi, where can i buy this transformer?
Thank you