Samsung SyncMaster 2493HM black screen with power

[rob85635]

Re: Samsung SyncMaster 2493HM black screen with power

more pictures

[retiredcaps]

Re: Samsung SyncMaster 2493HM black screen with power

Yes, I have a multimeter but I only use it rarely and to measure AC and DC voltage and I am unfamiliar with the other features but I will learn as needed.

1) On the power board, let's get DC voltages for each connector pin circled in red. Put your black probe on the ground screw that I circled for all readings. Put your red probe on each pin and report the voltage along with its legend/label. For example,

Connector CN200
pin 1 - label 5VSB - my reading is 4.99V

2) On the logic board, there is one voltage regulator that I can spot. Put your black probe on the ground screw that I circled for all readings. Put your red probe on each pin (3 pins - ignore the top tab) and report the voltage along with the part number of the voltage regulator.

3) For bonus points, post a picture of your multimeter.

[selldoor]

Re: Samsung SyncMaster 2493HM black screen with power

Pictures although plentiful are not really clear enough for troubleshooting - they need to be really clear ,as near to 2 MB as you can get. As your blue light is on i guess the two white fuses on the powerboard are ok but you may as well test them. With power off, meter on ohms setting- note what it registers when you touch the probes together, then one probe on each end of the fuse - you should get the same/ similar result.
There is another fuse - see pic 5 in last series there is a small white block the label nearby says 7A 125V. Please measure that in the same manner and post results.

[rob85635]

Re: Samsung SyncMaster 2493HM black screen with power

Here is a picture of my multimeter for the bonus points. I will get those measurements ASAP but my 3 year old daughter swallowed a hair clip that so far has not passed naturally so we have to go back to the ER and get another X-Ray to see what the next step is. Thanks again for all the advice so far.

Rob

[retiredcaps]

Re: Samsung SyncMaster 2493HM black screen with power

Here is a picture of my multimeter for the bonus points.

Nice multimeter. One retiredcaps bonus point awarded.

I will get those measurements ASAP but my 3 year old daughter swallowed a hair clip that so far has not passed naturally so we have to go back to the ER and get another X-Ray to see what the next step is.

Your daughter is definitely your first priority.

When you have time, we will also need a picture of the panel board. This is the board that runs the entire length of the lcd. It is usually found at the top of the monitor sometimes underneath some metal shielding. This panel board may have a fuse on it which may require testing.

[rob85635]

Re: Samsung SyncMaster 2493HM black screen with power

Ok, I will get a picture of that as well.

Rob

[Jimmy Neutron]

Re: Samsung SyncMaster 2493HM black screen with power

I stumbled on this site a few days ago while I was also looking for a fix for my Samsung 2493hm monitor. I have a fix for most of you and the cost is $1.39, you you really should opt for a "complete" fix that will set you back a total of $9.64. Let me explain.

I also just bought an unworking Samsung 2493HM LCD monitor. I am a DIY'er guy and I love to frequent my local GoodWill stores as they always have vintage stereos that I love to buy and restore. My Goodwill has a computer department with a huge assortment of both working and non-working computer gear. Sometimes they have great deals on non-working, but easily fixable LCD monitors and TV's. Last month I bought a 55" Vizio LCD 1080p monitor for $20.00 because it had no picture. $10.00 later I repaired it and now is in our main bedroom working with no issues. Great deal! Most LCD monitors are all built the same, and the fix can be applied across many units. Fixes are roughly 90% power supply issues, or 10% LCD screen issues. Fixing a power supply is almost a guarantee that for under $10.00 you will have it running again. But if it's a bad screen - forget it. So, I found a beautiful mint looking Samsung 2493hm monitor for $20.00 with a blue power light but no picture. This is classic power supply issue. I bought it, took it home, found a web site that details the fix, and now my monitor is working flawlessly.

The problem is that the capacitors in the power supplies of most all LCD monitors are severly under rated and their life span is very short. Also, they are prone to electrical power surges from the owners home. In this Samsung there are a total of 12 capacitors in the power supply board. Sometimes the bad cap, or caps, are obvious and upon inspection look like they exploded from the inside out. But sometimes they just bulge. In order to fix the Samsung you really should replace all 12 capacitors. The total cost is roughly less than $10.00 and all you need is a good soldering gun, solder, solder remover, and about 30 minutes. When you remove the old capacitors you need to be carefull to not break any other things around the area you're working in. Use a good solder removeal suction tool or suction baloon to remove the old solder. A solder wick is also good so that you can remove all old solder from the board. This step is really important because if you leave old solder on the board thinking you can "reuse" it, you'd be wrong. The board must be clean of the old solder before you install the new caps. Be sure to use the correct polarity when installing the new caps. On the board you will see the round outline of where the capacitor sits, and half of the round outline is shaded. This is the negative side and is where you will place the negative wire from the capacitor. Use only the rated caps or you will run into problems on power up!! When you solder be VERY, VERY stingy in the amount of solder that you use. This is VERY important. DO N OT USE A LOT OF SOLDER!!! Doing so will not make a good connection, and you stand a very good hance of having a solder blob spill over onto another componet, thereby creating a short and damaging a lot more. Just a little dab of solder is all you need. Place the solder tip in the board/wire for about 2 seconds, then add solder for a split second, then pull away. The solder should be a small silver "hill" rather than a "pimple" or "blob". If it isin't a small hill then do it again. Remove and clean the blob, and try again. Practice on an old VCR you have in the garbage can in advance. If you don't have a good solder joint then it won't work. After you've soldered all the new caps in place, and cut off the excess leads, and made all connections, you are ready to fire her up.

If you did the job as described then you should have a working monitor. If you don't have a picture then you need to start all over and look for bad solder joints, etc. Here is a page that details the process in detail, along with the capacitor parts list. http://www.ccl-la.com/blog/index.php...4-lcd-monitor/

Good luck.

Jimmy

[budm]

Re: Samsung SyncMaster 2493HM black screen with power

So what kind/type of capacitors did you use for the repair?
http://en.wikipedia.org/wiki/Capacitor_plague
Higher voltage will not take care of the problem. Type of caps and poor quality caps are the main problem.

[Jimmy Neutron]

Re: Samsung SyncMaster 2493HM black screen with power

I used just standard caps that my local electronics shop had - nothing like Nichon or the like. While I'm sure that those would extend the life of the monitor, I don't thing that spending for the difference will do anything to make or break the fix any different. If Samsung used standard caps, then you can buy standard caps for the fix. With that said, replacing with better caps will undoubtedly extend the life of the monitor. IHO, if you can swing it, go for the better caps. If not, don't worry about it. It's up to you, but not a neccessity.

Jimmy

[selldoor]

Re: Samsung SyncMaster 2493HM black screen with power

Well Jimmy, all I can say is you have been very lucky with your purchases. If you actually spend a bit of time reading the posts on here you will see that most of them do not relate to simple replacement of capacitors. If only they were!
Some of them even relate to machines where the owner has "fixed" it with local store general purpose caps, causing a more complex and expensive failure a few weeks later.
You dont even mention fuses, diodes, resistors ,transformers, inverters
thermistors, voltage regulators, transistors, bridge rectifiers, eeproms, software, mosfets or anything else that goes wrong, or is that covered by
"etc"?

Even in this thread "MadOne_NL" replaced only his bridge rectifier yet you say if he had followed your advice he would have a working monitor.

Also, as you refer us to http://www.ccl-la.com/blog/index.php...4-lcd-monitor/
perhaps you should read it again.
Read comment 1 and the reply, then click on the link to capacitors and read the part that says

"When repairing LCD monitors....very important to use the right parts or you will have to do the repair again soon or even worse it may damage the unit even more........The general purpose capacitors like you would find at Radio Shack will not work for LCD monitor repair."

[budm]

Re: Samsung SyncMaster 2493HM black screen with power

Well, selldoor, people will learn by making mistake, we have been here long enough to learn from real life experience people here that fix thousand of broken monitors, TV, power supply, or anything that is plugged into the outlet, there is no better convincing until the 'fixed' equipment is broken again after a few months with more damages. Live and learn.

[Jimmy Neutron]

Re: Samsung SyncMaster 2493HM black screen with power

Well Selldoor, I didn't mention fuses, regulators, etc because they are not related - for the most part - to fixing this Samsung monitor when it has an issue as described here - blue power led is on but no picture on the screen. A quick google search w will pull up many sites where the majoriity off the problem with this Samsung monitor, and most LCD monitors in general, is that the capacitors in the power supply go bad.

I didn't search out the entire internet to find this one particular website just to register and give false or misleading information. I took the time to post my problem with my Samsung monitor (which is very similar, if not identical, to some other members problems) and I posted what I did to fix my monitor. It was cheap, it was easy, and it works. I just thought I'd share my experience in order to help out others who have the same issue and can't afford to pay a technician their price and replace all sorts of componets and spend too much money for their fix. It's easier to spend $10.00 and 30 minutes and try this capacitor swap. Instead the response I got was not a "Hey thanks. I'll try that", but instead a "F you dude. You didn't read anything. You used Radio Shack parts. THe link says they won't work. Blah, blah, blah".

Whatever. My Samsung was repaired as i described it and I've been using it daily ever since with no issues. I'm typing on it right now. Yours isin't. So good luck on your search to repair it. And BTW, I NEVER said I used Radio Shack parts. I said to make sure you use the CORRECT CAPACITORS. It seems YOU were the one not reading the posts.

Again, good luck on your quest to repair your monitors. I posted, and now I'm off this forum.

Jimmy

[budm]

Re: Samsung SyncMaster 2493HM black screen with power

Low ESR? or general purpose caps?

[Groucho]

Re: Samsung SyncMaster 2493HM black screen with power

Re: Samsung SyncMaster 2493HM black screen with power

[Groucho]

Re: Samsung SyncMaster 2493HM black screen with power

Re: Samsung SyncMaster 2493HM black screen with power

Sorry about cryptic start. A bit new at this. Been following info with interest as have the same problem with the same monitor. Black screen, clicking sound & then nothing.
Had electronics friend look at it. Checked all caps with an ESR meter and found them all good. He said it was the worst soldering on any commercial boards he's ever seen. Found a lot of dry joints. Resoldered most components, especially a bad transistor connection. Been going well since. Said many boards give a short term fix when removed as connections improve but fail shortly later again when heat generated causes another circuit breakdown. Based on my experience, cost nothing but time and solder. Hope this is helpful. All the best to anyone who has this problem.

[backergr]

Re: Samsung SyncMaster 2493HM black screen with power

Started out snapping, then went dard with BLUE power light remaining lit. On/Off would leave the screen dark but power light on solid.

After a prolonged power down sequence and turning it back on the power light would come on and screen remained black. I left the monitor on (permanently) at that point and used the computer to blank out the monitor after 15 mintues.

Ran that way for weeks, then one day while using it the SNAP occured, screen went black and power light began flashing.

Have had the 2493 apart several times, replaced the 12 caps via CCL-LA but the flashing LED power light problem continues.

Will check fuses then follow the measuring voltages on points/pics that were previously posted.

Can't be just a fuse, can it????

[Rtech]

Re: Samsung SyncMaster 2493HM black screen with power

Some questions and answers then....have no idea what 'SNAP' means with reference to monitors ???/you have replaced caps, with what make etc ??/Flashing Powerlights normally caused by bad caps OR short circuit output transistors in the Inverter.You need to attach photos of boards using the 'Go advanced ' below ,and then 'manage attachments'

[johnwartjr]

Re: Samsung SyncMaster 2493HM black screen with power

I am working on a Syncmaster 2493 as well.

The screen is black. The power LED never illuminates.

I have tried another power cord.

If I connect the monitor to a computer using a VGA cable and power it on, the computer detects the monitor.

It belongs to a friend of mine who said it made a loud quacking noise before it failed.

I have a DMM, an ESR meter, and good rework equipment. I tested all the caps on the power supply with the ESR meter and all are within 10% of their rated values.

Any suggestions where I might start?

Thanks!

[newbie1]

Re: Samsung SyncMaster 2493HM black screen with power

You can start by chechking the 2 main fuse near the power cord. Also the 'Green' resistor beside the main capaitor and the 0.22ohms infront of the 2 mosfets in the middle of the board.

P/s: i gave up troubleshooting 3-4 boards of this model and replace them with another compatible power board set because mine all had transformer busted due to that darn yellow glue.

[McEugene]

Re: Samsung SyncMaster 2493HM black screen with power

solved case that worked for me after all procedures above failed in my case:
my psu is a BN44-00195A model 245B2 (slightly different part numberingfrom schematics above)
symptom was:
a black screen with blue power light steady on.
5,2V standby power was ok, primary PFC voltage was ok (380V for my european 220V input monitor). but the backlight 24V was not there ...(5.3V was not their either since it is a byproduct of the main 24V output...).

what I did:
A) replaced most polarized cap though all my caps looked ok (no bulging top)---> still black screen
B) checked for the yellow glue becoming conductive, clean up a couple of components ---> still black screen (no 24V out)
C) checked the operation of the MC33067P ICM801
pin 14 was always high and pin 12 alway low...check the oscillator (pin 2 ) and their was no oscillations there, so I started looking at reasons for not startup of the IC in the datasheet...
pin15 12V was ok (power supply)
pin 8 non inverting output of error was 5.1V =(ref voltage of the IC) --> force max oscillator frequency in principle...

pin 10 fault input was low when I mesured it...so in principle all was ok , no fault detected ...
By reading the datasheet of the IC , I noticed that if there was a pulse greater than 1v on the fault pin the IC would lock itself to prevent serious damage and remain in that state until power is removed...
It was a long shot but I decided to connect my DSO (! use double 12V-220V AC 3A transformers back to back on the 220V ac input to allow the whole supply to float and prevent to blast my scope inputs!!!! Ov of the scope is connected to earth in principle...)
So, i measured (captured) the Pin 10 level as I flipped on the power switch of the PSU and I noticed a tiny 10ms 1.1V pulse on the fault line after 200ms then the line was perfectly below the 1V threshold of the fault input pin (pin10)...I was nearing the solution.
There are two separate circuits tha can trigger a fault condition on pin 10:
1)- the overvoltage monitoring circuit via opto PC802S on the schematics(PC804S on my PSU model)
2) the "feedback/monitoring circuit" from the primary of the TM801S transformer (DM805-CM809-RM815 on the scematics)

on the overvoltage monitoring circuit, I disconnected the 0 ohm resistor (it not on the schematics, but on the PCB is is easy to find by following the tracks)
between the PC802S opto led cathode and the LMBT2222 transistor to desactivate that circuit and measured again the power up sequence on pin 10 ---> the 10ms pulse high was still there....
Then,
I checked carefully feedback components from the the primary of TM801S transformer and noticed nothing abnormal at first, then I notice some of that yellow hardened glue on the 47pF 1KV capacitor (CM809 on the schematics) in the feedback circuit. That glue was covering both legs of the capa!!! It was a long shot but I decided to desolder the capa and clean it up as nice as possible without breaking it...soldered it back...and it WORKED! The MC3306P was oscillating nicely and the 24V was back, I reconnected the 0 ohm resistor of the other monitoring circuit and all was OK.
My 2493HM monitor is back to life and so far it as been working perfectly again...

So my advice is CHECK the Yellow glue on all critical components and remove it if you can!!!

Now I know that PSU quite well since I have been working on it for a complete day or so....Since I have two of those monitors I am ready for the second one when it fails (hope not but...)