Getting started with troubleshooting [Samsung 245BW]

[clarioncapacitor]

Re: Getting started with troubleshooting [Samsung 245BW]

Wow you guys really cover everything on here! This thread really helped me figure out what was wrong with my monitor and hopefully when I get the parts it will be fixed!

[nerdbot]

Re: Getting started with troubleshooting [Samsung 245BW]

If those pins were broken in any way the problem would have been no backlight, not backlight and white screen. This is definitely a LCD, cable or logic board issue.

Well, I think it's the actual LCD panel. I got a different logic board and a new LVDS cable, as well as new cables between the logic board and power board, and I get the same behavior: solid white screen.

Out of curiosity, I connected my wife's 24" monitor (a Dell) to the current limiter, and when I turn on the monitor the light bulb flashes while the LCD is dark, then the LCD tries to turn on while the light bulb dims, and it alternates back and forth like this. I also have the same result when I connect it to my 20" monitors, so I assume this behavior is the "correct" behavior for a working monitor.

I then connected the LVDS cable on the 245BW while still using the current limiter, and this time the light bulb stays lit constantly. The LCD screen flashes momentarily then goes black, while the light bulb lights up and stays lit. Does that confirm that the LCD panel is what's drawing too much current? (As I mentioned previously, without the LVDS cable connected, the current limiter behaves "normally")

[nerdbot]

Re: Getting started with troubleshooting [Samsung 245BW]

Ok, thanks for the info. I guess I'll look into RMA'ing the logic board or getting a new LVDS cable.

[Th3_uN1Qu3]

Re: Getting started with troubleshooting [Samsung 245BW]

If those pins were broken in any way the problem would have been no backlight, not backlight and white screen. This is definitely a LCD, cable or logic board issue.

[nerdbot]

Re: Getting started with troubleshooting [Samsung 245BW]

Another observation I made was that on the replacement power board I received, the smaller connector between the power board and the logic board was bent (but does not seem broken) - I attached a picture and boxed it in blue.

This connector has the BL_EN and SOS pins, and I believe a DWM or DIM pin (I can check again when I get home). If this connector is actually damaged/broken on the power board, would that explain the constant white screen on my monitor?

If so, I'll probably try removing the 5 pin transistor on this new power board and put it on my old power board.

If not, I may try to RMA this logic board instead.

[nerdbot]

Re: Getting started with troubleshooting [Samsung 245BW]

I double-checked the signal cable from the logic board to the LCD panel, and it appears to be properly seated, yet I still have a constant white screen. Could the cable be bad? Is there any way to test it (short of buying a new one)?

[Rtech]

Re: Getting started with troubleshooting [Samsung 245BW]

Check that you have plugged in the connector between logic and LCD panel correctly.A lot of members have forgot to do this,myself included, when putting the Monitor back together.

[nerdbot]

Re: Getting started with troubleshooting [Samsung 245BW]

I got the replacement logic board in, wired it up, plugged it in to the current limiter, and left the inverter board unplugged. I tested a bunch of voltages to make sure things looked ok (S_B, 5.3V pins, 24V pins, voltage across the main capacitor, resistance on the various transistors with the power off, etc). Things looked ok, so I wired the rest of it up and connected the inverter board and a VGA cable.

The monitor turns on, and nothing popped, but the screen was bright white with no picture (but no longer flickering/flashing). If I moved a window onto the screen, I can see some movement (mainly very faint blue/pink streaks) that matches relatively where the window should be, but still no picture. Is this a D.O.A logic board?

One thing I did notice was that on the BL_EN pin between the logic board and power board, the voltage was reading 5.2V. The troubleshooting guide says to check that pin for "high voltage (3.3V)". Does 5.2V on that pin indicate a problem?

[nerdbot]

Re: Getting started with troubleshooting [Samsung 245BW]

I dunno if this is worth 40 bucks but you might as well try if you really want to fix it. Do check all voltages on the power supply before connecting it to the new logic board, just in case something IS actually wrong with the PSU.

Yeah, I hear you, but I figure I've already spent this much, may as well try one last time. I think the grand total I've spent so far on the 245BW, including the logic board I just ordered, is a little over $60, which is still a bit less than buying one brand new power board, and a lot less than buying a new 1920x1200 24"+ monitor. If this new logic board doesn't work, then I'll give up.

It's kind of crazy how much more expensive 1920x1200 monitors are over 1920x1080s. Must be a supply/demand thing.

[Th3_uN1Qu3]

Re: Getting started with troubleshooting [Samsung 245BW]

I dunno if this is worth 40 bucks but you might as well try if you really want to fix it. Do check all voltages on the power supply before connecting it to the new logic board, just in case something IS actually wrong with the PSU.

[nerdbot]

Re: Getting started with troubleshooting [Samsung 245BW]

I don't think so. I think that unfortunately the main processor (the Genesis chip) is bad, and its excess current draw blew the diode.

Ah, ok. Let's hope so Luckily, I was able to get a (supposedly) working logic board off of ebay for $20.

[Th3_uN1Qu3]

Re: Getting started with troubleshooting [Samsung 245BW]

I'm guessing something else is bad on this different power board that caused D701 on the logic board to blow?

I don't think so. I think that unfortunately the main processor (the Genesis chip) is bad, and its excess current draw blew the diode.

[nerdbot]

Re: Getting started with troubleshooting [Samsung 245BW]

Well, I'm back. I ended up getting that used power board off of eBay for $20, and I replaced all the caps on it. I plugged it in to the logic board, connected the front bezel, and plugged everything into the current limiter power strip. I turned on the power switch on the power board, and the light bulb flashed momentarily then went dark. I then turned on the monitor and again, the light bulb flashed momentarily, then went dark, while the blue power LED stayed lit. From what I understand, this is correct behavior.

I then unplugged the monitor, connected the power board to the inverter board, and plugged the monitor into a regular outlet and turned it on. The power LED came on, the backlight came on, but it is solid white. Also, as soon as the backlight came on, something on the logic board popped. I attached a picture. It's labeled D701. Even after D701 popped, the backlight remained on.

When I connect a VGA cable to my laptop and set it to use the 245BW, the backlight comes on, the screen is white like before, but it flickers often, but with a random pattern.

I'm guessing something else is bad on this different power board that caused D701 on the logic board to blow?

[Rtech]

Re: Getting started with troubleshooting [Samsung 245BW]

Farnell,UK 509 in stock:-
http://uk.farnell.com/allegro-sanken...Ntt=SI-8008HFE

[nerdbot]

Re: Getting started with troubleshooting [Samsung 245BW]

The ebay one for $20, if you look closely at the picture, has at least one bloated cap (near top right hand corner). The auction does state "The monitor was starting up after a long wait." so it could be a simple recap to fix this power board?

Yeah, I did notice that, though it still is a gamble. Maybe I'll wait until closer to the end of the auction. If I can get get it for closer to $20 (instead of the buy it now of $34), I might be inclined to try it (I did buy twice as many caps as I needed when I originally ordered the replacements caps for the 245BW...)

Are there are any dead monitors in the bin that you can get?

The monitors that are in there are often either dead KVM LCD panels or CRTs.

[retiredcaps]

Re: Getting started with troubleshooting [Samsung 245BW]

1.) Currently, I can either get the BN44-00195A board from eBay

The ebay one for $20, if you look closely at the picture, has at least one bloated cap (near top right hand corner). The auction does state "The monitor was starting up after a long wait." so it could be a simple recap to fix this power board?

My company has an electronics recycling bin, but that's usually filled with larger electronics (computers, monitors, motherboards, etc)

Are there are any dead monitors in the bin that you can get?

[nerdbot]

Re: Getting started with troubleshooting [Samsung 245BW]

I attached pictures of the red, green (both marked "EN210A 8222EN", and light blue ("FCQ1A04") transistor .

When I pulled out the red transistor and measured it again, I got the following readings (counting pins from left to right using the attached pictures):

Black Pin 1, Red Pin 2 - Out of range
Black Pin 1, Red Pin 3 - Out of range
Black Pin 2, Red Pin 3 - 140.8 Ohms

Since the little icons on the transistor looked like diode symbols, I also tried:

Black Pin 2, Red Pin 1 - 140.7 Ohms

And just for kicks:

Black Pin 3, Red Pin 1 - Out of range
Black Pin 3, Red Pin 2 - Out of range

Because these readings looked better than when in-circuit, I pulled all the transistors and tested them. Out of circuit, the green transistor tested similarly as the red above:

Black Pin 1, Red Pin 2 - Out of range
Black Pin 1, Red Pin 3 - Out of range
Black Pin 2, Red Pin 1 - 141.5 Ohms
Black Pin 2, Red Pin 3 - 141.3 Ohms
Black Pin 3, Red Pin 1 - Out of range
Black Pin 3, Red Pin 2 - Out of range

Light blue transistor:
Black Pin 1, Red Pin 2 - Out of range
Black Pin 1, Red Pin 3 - Out of range
Black Pin 2, Red Pin 1 - 116.5 Ohms
Black Pin 2, Red Pin 3 - 116.4 Ohms
Black Pin 3, Red Pin 1 - Out of range
Black Pin 3, Red Pin 2 - Out of range

Magenta transistor:
Again, I tested using the black on pin 3, since the datasheet indicates that is the ground pin. Sadly, after pulling this one out, I could see what looked like a blister on the front (picture attached), and it tested similarly to when it was in-circuit

Black Pin 3, Red Pin 1 - 20.1 ohms
Black Pin 3, Red Pin 2 - 21.4 ohms
Black Pin 3, Red Pin 4 - Out of range
Black Pin 3, Red Pin 5 - 604 ohms

So I'm thinking, of course, the one that is broken is the one that's hardest to find?

If the 5 pin IC is bad, I use findchips.com

http://www.findchips.com/avail?part=8008HFE

However, the cost of replacing all the shorted ICs may only be the beginning. Other components may be shorted after replacing these.

If you want the satisfaction of potentially fixing your board, then you may want to replace whatever ICs are shorted.

Well, in the course of troubleshooting my 245BW, I have fixed 3 other monitors - my smaller and older Samsung 204B, and 2 for friends, so I have felt the deeply satisfying feeling of bringing back monitors from the dead with my own 2 hands I won't lie though, it would've been nice to get the 245BW working w/ just a few replaced parts - but I see that one of the suppliers RetiredCaps' provided that can ship to the US has a $20 handling fee for a $4 part. Similarly, I can get a "non-working" (as in they don't know exactly what's wrong with it) BN44-00195A from eBay for $20 + shipping, but who knows if the transistor I'd need is working on that one either.

While I'd like to go 4 for 4 with revived monitors, $24 is about 30% of the way towards a brand new power board. So, sadly, I think I'll cut my losses here

Regardless, it's been a great learning experience for me, and I had a lot of fun learning how to solder and fix these monitors. Prior to this, I knew enough to just buy the replacement boards for dead monitors, which was still a better deal than replacing them completely. Now I know I can often fix them for far less than that! I really appreciate everyone's help with educating me along the way.

A few remaining questions:

1.) Currently, I can either get the BN44-00195A board from eBay (as a board pulled from a previously working monitor, supposedly working and not the same as the "non-working" one I mentioned above) or from partstore.com brand new. Has anyone had any experience with partstore.com?

2.) I tried searching the forums but I didn't have much luck - what's the proper way to dispose of the capacitors I've removed? My company has an electronics recycling bin, but that's usually filled with larger electronics (computers, monitors, motherboards, etc), and I hear those just get sent off to China to be scrapped for parts.

[retiredcaps]

Re: Getting started with troubleshooting [Samsung 245BW]

If the 5 pin IC is bad, I use findchips.com

http://www.findchips.com/avail?part=8008HFE

However, the cost of replacing all the shorted ICs may only be the beginning. Other components may be shorted after replacing these.

If you want the satisfaction of potentially fixing your board, then you may want to replace whatever ICs are shorted.

[Th3_uN1Qu3]

Re: Getting started with troubleshooting [Samsung 245BW]

If it's the 5 pin ones, yes, you're going to have a hard time locating them. They are custom parts that go out of production soon after they're released. A new power board would be a good idea.

[nerdbot]

Re: Getting started with troubleshooting [Samsung 245BW]

Hmm, all the above readings would suggest that all those 4 components are possibly shorted.

Given how QM802 andQM803 were bad, it is possible that this board got some severe damage?

I would desolder just one transistor (say the red circled one) and retest it for a short. There could be something "in circuit" that gives these 4 transistors a "false" reading?

If you want to minimize the work involved in desoldering the red circled transistor, try to just "lift one leg" of the transistor and retest.

I guess anything's possible... I recall saying earlier how I was surprised I didn't screw up something bigger sooner Could it be that when I tried those first two resistors (before fixing the QM802/803 mosfets) that it caused damage to the other 4 transistors? When the resistors blew, I didn't turn off the power immediately, but maybe 15-20 seconds later.

I'll desolder one of them in the morning. If it does turn out that they are shorted, I believe Th3_uN1Qu3 said they were kinda hard to find. I guess at that point I'd be looking at just buying a new power board?