Re: Samsung 245B+ - BN44-00173A - No backlight (24v)
IC801S had 0 volt output. So i checked if Vcc was present on pin 6. There wasn't any voltage. I went checking QB802 but it was fine.
I don't know what happened next (probably i bridged something that souldn't be bridged) and both fuses blew up. I took out the bridge rectifier (thinking was the problem, since i have a short between + and -) but i still have a short.
I spent too much time on this and i think it's enough.
I have a couple 220/24v transformers laying around, so i'll probably just...
IU5ICI
Member
Last Activity: 01-22-2017, 10:08 AM
Joined: 01-11-2017
Location: Arezzo
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Re: Samsung 245B+ - BN44-00173A - No backlight (24v)
Ok, here I am again.
I replaced ALL electrolytic caps but the problem didn't change.
I still had 24v only without load: turning the PS on, the voltage was slowly rising to 24v but using just a 200ma load the voltage was dropping to 0.
Something got worse, since I don't have any voltage anymore, either without load: when I plug the PS, voltage slowly rise to .4-.5 volts then slowly drops to 0.
Across the big cap (CP803) I have about 390Vdc.
I checked diodes (DM851,DM852,DM854) but they...Leave a comment:
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Re: Samsung 245B+ - BN44-00173A - No backlight (24v)
Ok, thank you. When i'll get new caps, i'll check that.
I've removed all elecrolytic caps (to order new) and i read their values.
I'm pretty sure the ESR value is completely wrong.
At least the capacitance is about the same as two other DMM (different brands), so i "trust" that.....Leave a comment:
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Re: Samsung 245B+ - BN44-00173A - No backlight (24v)
My ESR meter is just a cheap chinese component tester.
But i can tell it isn't good at all.
...
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Re: Samsung 245B+ - BN44-00173A - No backlight (24v)
Honestly i don't know where i should check for PCF Voltage.
I made a new thread cause the problem was different.
And yes, you are right, CM802 is 17nf not uf. i should learn to read.
[QUOTE =CapLeaker]Picture #3 bottom right. There are 2 large caps next to the inductor. Those look like they run hot, as the sleeve shrunk a little (high ESR). Change them out. I believe it is CM862 and CM863. It should be a 10V 2200uF and a 35V 470uF. Those 2 caps don't look good to me at all.[/QUOTE]
...Last edited by IU5ICI; 01-12-2017, 03:15 PM.Leave a comment:
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Re: Samsung 245B+ - BN44-00173A - No backlight (24v)
Here they are. The illumination isn't the best, but you should still see.
In the last pic, the bridge between S_B and PSON is there just to turn on the power supply.
The 3 68ohm resistor are soldered badly (they ruined the PCB when they replace them but the solder is solid. They just need to be connected in series. No PCB need it the middle of the joint)
If you need something else, just let me know. Thanks...Leave a comment:
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Samsung 245B+ - BN44-00173A - No backlight (24v)
Hi all,
I have this monitor (Syncmaster 245B+) that turns on but doesn't have backlight.
Reading around, I replaced the 3 68ohm resistors but without luck.
Turning on the power supply (3.3kohm resistor between 5v and PS_on) with the lamp module connected I have 0V on 24V rail.
If I disconnect the lamp module I get the 24V but even with a 200ma load, the voltage drops to about 9v.
If I brutally connect an external 24V power supply directly on the 24V rail, it all works fine (No short, nothing getting hot) and the monitor works fine.
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Re: Samsung 245BW Not Powering Up
Ok today I'm dumb. I measured cp803.
CM802 it's fine (17.16nf)Leave a comment:
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Re: Samsung 245BW Not Powering Up
I mean 78uf..sorry. Lapsus
I was checking resistors....Leave a comment:
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Re: Samsung 245BW Not Powering Up
It's 78ohm with 1.2ohm ESR...Leave a comment:
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Re: Samsung 245BW Not Powering Up
Hi all, i have a similar problem with a 245B+ with board BN44-00173A.
The monitor turns on but i don't have backlight.
+24V is missing (is present without load but with just 200ma load it drops to 9v).
If i brutally connect an external 24v power supply directly on the 24v rail, it all works fine (no short, nothing getting hot, etc)
I've already replaced the 3 resistors but i still have to replace caps.
Can it be a bad caps related problem?
Does anyone have a full cap list ?
...Leave a comment:
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Re: New Members - please post your introductions here
Hi all guys.
I'm IU5ICI and i'm here to learn..
73'sLeave a comment:
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