Samsung 2493 HM issue

[zulururu]

Re: Samsung 2493 HM issue

Unfortunately no !

[Toasty]

Re: Samsung 2493 HM issue

Was this ever resolved?

[PlainBill]

Re: Samsung 2493 HM issue

With all the hard work you are doing, you deserve a good meal ;-)
I just had homemade veal paupiette (stuffed escalope of veal) with mushrooms onions and cram sauce ! It was good too !
Here is what I find for the opto isolators:

Power OFF:

A/ 1.13V
B/0.66V
C/19.4V

Power ON:

A/ Fluctuating between 2.2 V and 9.5 V probably going even higher if I leave the probes o it for a longer period of time.
B/1.7V
C/0.15V

By the way, you remember when I told you the main capacitor voltage was stucked at 164V power On AND power Off, well today, it's changing again from 164V Power OFF to 380V power ON .... strange !

Not that strange. We've had one successful repair of the BN44-00214A power supply (same controllers) that turned out to be a bad solder joint. I've had two power supplies that started working after having been shipped across the country. Your experience could be due to bad solder joints also.

By the way, based on your results, C is the opto-isolator turning on the PFC controller and main SMPS controller.

PlainBill

[zulururu]

Re: Samsung 2493 HM issue

With all the hard work you are doing, you deserve a good meal ;-)
I just had homemade veal paupiette (stuffed escalope of veal) with mushrooms onions and cram sauce ! It was good too !
Here is what I find for the opto isolators:

Power OFF:

A/ 1.13V
B/0.66V
C/19.4V

Power ON:

A/ Fluctuating between 2.2 V and 9.5 V probably going even higher if I leave the probes o it for a longer period of time.
B/1.7V
C/0.15V

By the way, you remember when I told you the main capacitor voltage was stucked at 164V power On AND power Off, well today, it's changing again from 164V Power OFF to 380V power ON .... strange !

[PlainBill]

Re: Samsung 2493 HM issue

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

Wasn't much 'Bon' last night; dinner was left over meat loaf.

On the other hand, tonight our house guest made boneless bottom round roast au jus, mashed potatoes with gravy, baked butternut squash with brown sugar, and broccoli with a light cheese sauce. Superb!! The only problem was she refused to let me wash the dishes.

I've marked up another picture. The output side of three opto-isolators have been circled, and labeled A, B, and C. Measure the voltage across each opto-isolator with power off and power on. One of them should show a major change in voltage, but report the results on all three.

PlainBill

[zulururu]

Re: Samsung 2493 HM issue

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

[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

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 ?

[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 .....

[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

[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.

[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 ;-)

[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

[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).

[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 !

[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.

[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

[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

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

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