Samsung 2493 HM issue

[alexanna]

Re: Samsung 2493 HM issue

Is it a question for me ?? if yes, my DMM doesn't have a capacitor range .....sorry !

Not exactly, I got the threads mixed up.
I am not really sure where you are on you monitor, I guess the point I was trying to make was there have been several failures of that capacitor. It sure wouldn't hurt to check the capacitance of it, and if the equipment on hand is unable to test it, I tried to give several suggestions on how to get it tested without spending a lot of money.

[zulururu]

Re: Samsung 2493 HM issue

Ah ok Thanks Alexanna !
I ordered an SMPS controller on August 19th apparently, it's coming from Australia and I still did not receive it, so as soon as I install it, I will let you know if that worked, if not, I will try to check that capacitor !
Thanks for the heads up though !
Cheers,

[zulururu]

Re: Samsung 2493 HM issue

After more than a month, I've finally received my SMPS controller ... but after installation, unfortunately, my monitor is still not working .... I still don't have 5.3v or 24v ....
Do you have anymore suggestion ?

[PlainBill]

Re: Samsung 2493 HM issue

After more than a month, I've finally received my SMPS controller ... but after installation, unfortunately, my monitor is still not working .... I still don't have 5.3v or 24v ....
Do you have anymore suggestion ?

Darn!!! I had temporary access to another BN44-00195A and made some measurements with the supply operating. Here is the comparison. As you can see, they are very similar. Unfortunately, I did not make measurements on other points on the board, and no longer have access to that supply.

Pin Yours Other one
1: 5.05v / 5.08V
2: 5.05v / 5.08V
3: 2.54v / 2.55V
4: 0.00v / 0.00V
5: 5.08v / 5.11V
6: 0.07v / 0.07V
7: 0.07v / 0.07V
8: 5.04v / 5.08V
9: 14.60v / 11.90V
10: 0.00v / 0.00V
11: 0.19v / 0.19V
12: 14.06v / 11.30V
13: 0.00v / 0.00V
14: 0.27v / 0.25V
15: 15.06v /12.2V
16: 5.04v / 5.07V

The next thing to test is CM812. I know your DMM does not have a capacitance function, so pull CM812, set your DMM to the 20 Megohm range, and touch the probes to the cap. You should get a reading that increases, eventually going open.

PlainBill

[zulururu]

Re: Samsung 2493 HM issue

Thank you Plainbill, I will measure that, also my DMM doesn't have capacitance function, I discovered I have one at work I can use which has capacitance function, should I use that one instead ? If yes, to measure capacitance, should I desolder CM812 or there is no need for it ??

[zulururu]

Re: Samsung 2493 HM issue

Hello again, I did the measurements with pin 4 as the ground and I have the same results +/-0.02v.... I will be waiting for your answer about CM812 and check it tomorrow .
Have a good day,

Zulururu

[PlainBill]

Re: Samsung 2493 HM issue

Hello again, I did the measurements with pin 4 as the ground and I have the same results +/-0.02v.... I will be waiting for your answer about CM812 and check it tomorrow .
Have a good day,

Zulururu

How about this - try checking it in circuit. If it reads 12nF +- 5%, it's good. If it reads anything else, pull it and check it out of circuit.

PlainBill

[zulururu]

Re: Samsung 2493 HM issue

I had to desolder to have a correct reading and I have 11nF so I guess it's good....

[PlainBill]

Re: Samsung 2493 HM issue

I had to desolder to have a correct reading and I have 11nF so I guess it's good....

Darn!!! Well, I'm going to go out on a limb and say that everything up to the driver transformer is good. As is my habit, I've marked up a picture.

Six areas of interest are circled, and lettered A-F. Standard precautions apply - don't electrocute yourself. Make sure any resistance measurements are made with the power off, any voltage measurements are made with the power on. You can use either the signal card or a 3.3K resistor to turn the main supply on.

F is a resistor, it is the resistor standing on end; it provides power to the transformer primary drivers. With power OFF measure the resistance.

E is a capacitor. With power on, measure the voltage across it.

A is the small transformer which isolates SMPS controller from the main FETS. Each yellow circle encloses the ends of one winding. Check for continuity of each winding.

D is the primary of the main SMPS transformer. Check continuity.

C are the main drive FETs. Check for shorts.

B Is a number of transistors and diodes that handle level shifting. Check for shorts.

PlainBill

[alexanna]

Re: Samsung 2493 HM issue

Here is another long shot! But it won't take long to check.
If my memory serves me correctly, on the other style Power supply the 24volt rail had to come up before the 5.3 volt would start.
I don't know if this has been tried, but I wonder if there is a problem with the 24V within the inverter causing the second half of the power supply to shut down.
Have you tried this with the inverter unplugged? See if the 24 and 5.3 Volts comes up.

[zulururu]

Re: Samsung 2493 HM issue

Thanks for you help !
Just to make sure, when you say "check for shorts" do I have to check for a resistance which mean with power off and in between 2 poles or between a pole and the ground ....or does it mean check for voltage between 2 poles or again between the pole and the ground ?? Excuse my ignorance !

[retiredcaps]

Re: Samsung 2493 HM issue

Just to make sure, when you say "check for shorts" do I have to check for a resistance which mean with power off and in between 2 poles or between a pole and the ground

Checking for shorts (i.e. resistance) is always done with power off. Any resistance reading under 30 ohms suggests the component is shorted. If it is a 3 pin component, measure pins 1-2, 1-3, 2-3 (all possible combinations).

[PlainBill]

Re: Samsung 2493 HM issue

Retiredcaps description is correct. When I say 'continuity', it means two points (in this case, the ends of a transformer winding) should be connected.

PlainBill

[zulururu]

Re: Samsung 2493 HM issue

Thanks again for the explanation !
I did the measurements, Here are the results:

A/ all around 0.7 ohm

B/ As per the picture below:

For the 2 upper ones
Between pin 1-2: 23,4 ohms
Between pin 1-3: 23,4 ohms
Between pin 2-3: 0.5 ohm

For the 4 lower ones:
Between pin 1-3: no continuity (infinite)
Between 1-2: no continuity (infinite)
Between 2-3: 0.5 ohm
R1: 22.5 ohms
R2: 22,6 ohms
R3:22.6 ohms
R4: 22.5 ohms

C/ As per the picture below
Between 1-6: 23 ohms
Between 2-5: 0.7 ohm
Between 5-4: 23 ohms

D/0.7 ohm

E/ O volt

F/ 6590 ohms


Alexanna, I tried to unplug the inverter board, with the signal card plugged in though and I don't have +24 v but around 0.05V, same results with the inverter plugged in...
Even if my monitor doen't work, I'm still learning a lot of stuff ;-)

[retiredcaps]

Re: Samsung 2493 HM issue

C/ As per the picture below
Between 1-6: 23 ohms
Between 2-5: 0.7 ohm
Between 5-4: 23 ohms

There are 2 FETs in area C. If my weak spatial mapping skills are correct, 1, 2 and 6 is one, 3, 4, and 5 is the other (as per PlainBill's numbering).

So you want to measure resistance (power off) between

1-2, 2-6, and 1-6.

3-4, 3-5, and 4-5.

You should have 6 readings.

[PlainBill]

Re: Samsung 2493 HM issue

Thanks again for the explanation !
I did the measurements, Here are the results:

A/ all around 0.7 ohm

That is reasonable.

B/ As per the picture below:

For the 2 upper ones
Between pin 1-2: 23,4 ohms
Between pin 1-3: 23,4 ohms
Between pin 2-3: 0.5 ohm

For the 4 lower ones:
Between pin 1-3: no continuity (infinite)
Between 1-2: no continuity (infinite)
Between 2-3: 0.5 ohm
R1: 22.5 ohms
R2: 22,6 ohms
R3:22.6 ohms
R4: 22.5 ohms

All of these are reasonable. The three legged components are actually dual diodes and zener diodes, I believe.

C/ As per the picture below
Between 1-6: 23 ohms
Between 2-5: 0.7 ohm
Between 5-4: 23 ohms

Please remeasure per retiredcaps suggestion.

D/0.7 ohm

This is reasonable; it's a transformer winding.

E/ O volt

F/ 6590 ohms

These are mistakes on my part. Of course, the resistor is E, and I would like you to measure the resistance (power off); the capacitor is F, and I would like you to measure the voltage across it (power on).

Alexanna, I tried to unplug the inverter board, with the signal card plugged in though and I don't have +24 v but around 0.05V, same results with the inverter plugged in...
Even if my monitor doen't work, I'm still learning a lot of stuff ;-)

PlainBill

[zulururu]

Re: Samsung 2493 HM issue

Oups, Sorry about the measurement of area "C":

1-2, 2-6, 5-3 and 3-4 gives me all no continuity (infinite resistance)

- "E" gives me 0.6 ohm

- "I" gives between 3V and 9V DC constantly changing .....

[zulururu]

Re: Samsung 2493 HM issue

Oops, here comes something else, I juste checked for voltage on the big 450V 82 uF capacitor for voltage and, power On as well as power Off I have the same voltage 163V ( I used to have 378V with power ON, 163V with power Off)..... did I do anything wrong ?

[PlainBill]

Re: Samsung 2493 HM issue

Oops, here comes something else, I juste checked for voltage on the big 450V 82 uF capacitor for voltage and, power On as well as power Off I have the same voltage 163V ( I used to have 378V with power ON, 163V with power Off)..... did I do anything wrong ?

Possibly. I have been unable to locate a schematic for this power supply, however the design is identical to the BN44-00214A in this thread.

I've being called away to fix dinner; I may not be able to get back to this tonight.

PlainBill

[zulururu]

Re: Samsung 2493 HM issue

Don't worry PlainBill, take your time and Bon appetit ;-)