Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

[techLTE]

Hello all, I wish I had found this community about a year ago!


Model: Samsung SyncMaster 2493HM
Power board: BN44-00195A
Main board: BN41-00962A


Description: Power button blue LED flashing non-stop when power plug connected. There is no change when the button is pressed and to clarify the screen does not power on at all. Visually I do not see anything other then the browning glue. I did notice a metallic burning smell but it seems to be coming from a heat sink more then anything.

Background: I swapped out the original power board with an eBay seller about a year or so ago. That being said, I decided to pull the controller board to visually inspect it as it may be the cause of power board failures or the failure itself this time. The controller board has a rattle sound, if I had to explain it a bb in a small can.

Additional Notes: I have a multimeter if need be and am willing to take any additional photographs if necessary.

While I'm technically inclined I am not an engineer and/or have no repaired surface mount components like many of you. I am willing to try though so thank you in advance for any time you contribute!

[selldoor]

Re: Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

OK - there are many threads setting out the problems with this board.
First major task is to remove ALL the brown glue. It is corrosive and conductive.
Check all the components it touches for rot.
Glue might be softened with IPA but needs scraped away with a dental pick, sharp blade - being careful not to damage the board.

[techLTE]

Re: Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

OK - there are many threads setting out the problems with this board.
First major task is to remove ALL the brown glue. It is corrosive and conductive.
Check all the components it touches for rot.
Glue might be softened with IPA but needs scraped away with a dental pick, sharp blade - being careful not to damage the board.

Thanks, yeah I did some research on the power boards last failure and have been searching here all morning. Thank for mentioning IPA, I keep reading to remove it but no one said with what! I'll start on that shortly and post pictures of my results/findings.

I'll keep searching for an explanation for the main board rattle, it just can't be normal.

[selldoor]

Re: Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

I'll keep searching for an explanation for the main board rattle, it just can't be normal.

I can probably answer that - will give you more time for clearing the glue

I think it is normal - it is a physical rattle yes? like when you shake/turn the board.
It is a rotatable screen and has a switch S301 which has a ball bearing in to
switch the display to match the screen.

[Davi.p]

Re: Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

connect all boards and plug the mains, then test all psu outputs and report here toghether with the tags written near each pin.

[Yaaman]

Re: Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

I am trying to fix a monitor with exactly same fault. In may case I had to replace to fets QM802/803 and power resistor RM801, zeners DZM802/3/4/5. Then DZT851/2, RT852 and QT851 as well as all electrolytic capacitors and the board still generates a fault.
Good luck.

[techLTE]

Re: Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

I can probably answer that - will give you more time for clearing the glue

I think it is normal - it is a physical rattle yes? like when you shake/turn the board.
It is a rotatable screen and has a switch S301 which has a ball bearing in to
switch the display to match the screen.

Thanks, I think that's it. As for this glue, it's killing me. I'm having a tough time getting this stuff off.

connect all boards and plug the mains, then test all psu outputs and report here toghether with the tags written near each pin.

Can you please elaborate on "the tags written near each pin"? tia.

I am trying to fix a monitor with exactly same fault. In may case I had to replace to fets QM802/803 and power resistor RM801, zeners DZM802/3/4/5. Then DZT851/2, RT852 and QT851 as well as all electrolytic capacitors and the board still generates a fault.
Good luck.

Ugh, sorry about your luck. Thanks for the insight and the well wishes.

[Davi.p]

Re: Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

Quote:
Originally Posted by Davi.p View Post
connect all boards and plug the mains, then test all psu outputs and report here toghether with the tags written near each pin.

Can you please elaborate on "the tags written near each pin"? tia.

Yes, write here the output measurements and near the label/markings you see near the connector.

[elektro.rs]

Re: Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

Hi, I have the same problem, the blue LED power button blinks. Checking supply plates, glue removed, measured capacitors - ejection / measured / soldered back, besides a large 82 micro F / 450V (I failed him vypájet). QM802 / QM803 OK. (Different markings of some components to the power board and schematic posted here).
When connecting only 230V AC supply plate only DC + 5,25V (S-B), the large capacitor 325V DC. When you connect the DC + 5,25V (S_B) with 1K resistor (PSOne), something starts beeping at regular intervals and voltage on (S_B) varies from 4,80V to 5,11V.
What else do I have zkontolovat?

Excuse my English.

Thank you

[elektro.rs]

Re: Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

Hi, could someone write these types of components:
ZDTM851, ZDTB851, ZDTM801

Thank you

[eaarnoudse]

Re: Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

Tonight, I repaired this power supply. I replaced two faulty FET's (FQPF9N50C) and the 0.22Ohm resistor. Besides, I desoldered the transformer between the FET's and IC MC33067P and removed all the brown glue. I soldered the transformer back and removed some brown glue on other parts. I preventively replaced the two 1000uF capacitors next to the white connector and one capacitor on the other side of the board next to the leaning diode. Fortunately all other smd diodes, zener diodes and resistors were OK. The monitor came back to life again!

[eaarnoudse]

Re: Samsung 2493HM - Power button blinking: BN44-00195A & BN41-00962A

@elektro.rs: You can download the schematics via this link:

https://cdn.badcaps-static.com/pdfs/...f8a620fd8c.pdf