Thanks! Agreed, just do it
FoxD
Member
Last Activity: 02-27-2016, 06:59 PM
Joined: 02-12-2016
Location: Rotterdam
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Re: Samsung 2493HM power board NO 24v to inverter
Thanks! Agreed, just do it
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Re: Samsung 2493HM power board NO 24v to inverter
Amazing! The transformer repair was a success!
I opened the transformer breaking the magnet in 5 pieces, found the burned wire, extended it with a small thin wire and connected it to the pin, firmly taped it back in place and glued the magnet into one piece using super glue. Finished it with re-taping the magnet. See pictures. Result: a working 2493HM again!
It can be done. I needed about an hour for this repair.
Thanks all for the tips and support....Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Thank you very much great people of this forum! You have given me enough confidence to try and repair the transformer. Later this week I should have some time to start this small project. I will document it with pictures and share it here. I hopefully can help others do this type of repair successfully (in case I succeed)
I would end this message with my reasoning behind the "coincidental" short by the glue in this monitor which could prevent some other failures for others when this is taken into account....Leave a comment:
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Re: Samsung 24" power supply BN44-00195A first stage voltage?
Did it work?Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
See the attached picture for the working TM801 transformer (taken from a different fully operational 2493HM PSU board), next to the heatsink, installed in the "faulty" PSU board being subject in this thread.
The board is now working properly. Hope to find another transformer or alike to get the known working other board back to life so I have both monitors running again.
So please! If you have one in a dead PSU board or just broke/damaged 2493HM or 245B you can make me a very happy man by offering...Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
QGAH00064 / DW07515
I will post a picture later.Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Before I put the working monitor back together I measured the VAC on the transformer with my DMM. I suspect the frequency of the signals to be higher than normal AC since my readings are drifting.
If I'm correct the primary winding is connected to the further separated legs. This measures 6VAC (readings from 5.7 to 6.0). The two secondary bindings are then connected to the closer separated legs. These measure 13.6-14.0 VAC and 6.8-7.0VAC.
Readings when monitor and display is on.
Any help on...Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
I searched for the part-number but they are not sold anywhere. I just find troubleshooting forums on this monitor and pictures.
I thought I could take the risk and I installed the good transformer (which I bottom-cleaned thoroughly while it was out!) in the faulty PSU and everything works as it should now.
Conclusion: Glue killed the TM801 transformer and without the TM801 no 5.3VDC and 24VDC.
Once more it is clear that cleaning the glue off is worth it, preventing damage which is very difficult...Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Just cleaned the transformer. The wire is gone, like evaporated. Trying to open the transformer to unwind one round seems like a destructive action. It's glued together and I will break the magnet when opening. I guess I run out of luck and need to find a replacement board or monitor.
Unless there is a way to replace this transformer with a different one that has similar specs. I can determine the winding count "relations" per leads in the working PSU.
Any last ideas how to overcome this problem...Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Thanks capleaker... You just gave me a handful of precision-work!
What about the chance repairing the transformer is the fix? I could try install the transformer from the working PSU, but if the fault is somewhere else I could end up with two dead transformers..
Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Thanks momaka, that looks like a good approach.
Unfortunately I found TM801 to be open on the side where the glue is. I desoldered to look at it from the bottom. Bad news: the wire from the middle pin is covered in black burned glue and no more sign of the wire. This might have happened after removing some glue to remove the cap it was glued to. Or this transformer has been overloaded due to the wrong value cap. Can some explain what the role of this transformer is and if it is related to the standby voltage of the 22uF...Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Small update: Managed to get the glue off the standing resistor without breaking it. It now measures 100KOhm (instead of 71). So they are now both matching their intended value. No power unfortunately. The glue here was definitely conductive.Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Thanks, found the ic! And three steps further:
1. More glue is removed, though not all, but visually all legs are now glueless.
2. Measured the two standing 100KOhm resistors next to the main filter cap which are covered in glue and cannot be cleaned without breaking them. One measures correct at 100KOhm. The other (next to the transformer) is around 71KOhm. Compared this with the working PSU and the values are both 100 KOhm. How big of a problem is this? I could replace these although I need to order them....Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Thanks budm. But this leaves me questioned where to go from now. Could it be a coincidence that the screen blacked while a wrong cap was installed? It's kind of strange the monitor worked based on your experience. But I also understand this does not stress any other component in the rare occasion the
I can't find the PFC ic looking for the FAN7530 , could it be the MC33067P? This ic has sixteen pins and I read this is a crucial part of the supply of 24V.
[url]https://www.badcaps.net/forum/showpost.php?p=358503&postcount=37[/url]...Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
After reading back and trying to do some logic reasoning I have a question.
1. With the wrong value capacitor installed (2.2uF instead of 22uF) the monitor had worked for about three hours. So the standby voltage should have been working. Despite it shouldn't work according to what budm said.
2. Could this wrong value cause extra stress on other components like the other new capacitors installed? Or any other component. Although I cannot see any component has died/been damaged, we now can tell for sure the PFC...Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Thanks capleaker. Makes sense. Just compared the faulty board with the working PSU.
The working PSU has 388VDC on the main filter cap when the screen is on. When I switch the screen off using the front panel button the voltage drops to 311VDC. Switching the screen (and blue led) on and off with the faulty PSU installed does not have any effect on the voltage: it stays 311VDC all the time.
Does this mean the PFC is broke or can it also be something else causing the PFC not kick in?Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Just tested the power board connected to the other parts and there is only 0.5VDC on the 5.3VDC supply to the video/control board.Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Did some measuring:
Standby voltage is 5.23V so is ok.
Voltage on main filter cap is 310V. Not close to 400V. Is this too low?
The standing resistor is not easy to measure on my (cheap) DMM. It measures a little higher than shorting the leads, about 0.3 Ohms. Is that close enough? You mention 0.22 Ohm as is correct with the code on the resistor.
The blue rectangular cap does have capacitance using my Ohm meter, although it seems polarity sensitive while in the circuit. I have no capacitance...Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
One additional comment. With the wrong elco installed the display did work for about three hours, including the front controls. After that it went to this state.Leave a comment:
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Re: Samsung 2493HM power board NO 24v to inverter
Thanks budm for the quick reply.
I have not yet measured the 5.2V standby. Will test that tomorrow when I have some time... Can I test that with the board isolated or do the Controller PCB and inverter PCB to be connected? And where to best test this voltage?
The blue led works BTW. And the buttons seem to work since my laptop responds to the source selection function. But since there is no display visible, also nothing with a bright flashlight I'm not able to confirm this.
I attached...Leave a comment:
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