Samsung SyncMaster 2693hm - Dead backlight

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

https://www.badcaps.net/forum/attach...0&d=1480973043
https://www.badcaps.net/forum/attach...2&d=1480973043

See those connectors? They have labels for each pin to tell us what they are for, so we need you to take DCV reading of each pin when the unit is plugged in but the power switch is not activated, then take the reading again after the power switch is activated.
You MUST report the readings in the format that we can easily read by putting down the PIN NAME, and follow by the DCV readings, very simple request. Black probe of the meter is on GND pin.

Easy to do and thanks for the information. On the way to get the multi-meter.

To confirm power is connected to power unit but no other connections. Testing on CNM802, CNM803, and CNM801 with power on and with power off but main still connected.

[budm]

Re: Samsung SyncMaster 2693hm - Dead backlight

We need the readings with everything all connected.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

We need the readings with everything all connected.

So pull values off the backside of the connector pins while up and running and also plugged in but off?

OK - thanks

[budm]

Re: Samsung SyncMaster 2693hm - Dead backlight

Correct.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

Correct.

OK - problem is getting everything connected and powered without shorting.

Since power and control board mount to inside of a back cover piece, I will need to have a non-conductive material insulator to place under the boards.

Will try to get measurements on Monday.

Thanks

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

Results as promised, just not when promised.
Meter @ 200 VDC

	On PSU - To E-PASS Board 		On PSU - To Inverter Board 	
PWR ON/OFF	3.2	BL/ON		4.8	24 V		15.2			
ST_BY		5.2	SOS		0.2	24 V		15.2			
GND		0	DIMMING		0.3	24 V		15.2			
GND		0	STATUS		5.1	24 V		15.2			
GND		0	24 V DET	3.1	24 V		15.2			
18 V		11.2				GND		0			
18 V		11.2				GND		0			
18 V		11.2				GND		0			
GND		0				GND		0			
GND		0				GND		0			
GND		0				SOS		0.2			
5.3 V		5.2				BL/ON		4.8			
5.3 V		5.2				DIMMING		0.3			
5.3 V		5.2				STATUS		5.1			
NC		0									
NC		0

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

Did confirm that power light on front is still working and that no backlight is being provided. My guess is that the low 18 V and 24 V are the problem so the PSU while looking good is not outputting the needed voltage. Open to being wrong.
Thoughts?

[budm]

Re: Samsung SyncMaster 2693hm - Dead backlight

You do have 18V/24V power supply problem.
You need to check the CAPACITANCE of CM824.
BTW, so C202 i ripped off the board?
https://www.badcaps.net/forum/attach...2&d=1481341030

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

BTW, so C202 i ripped off the board?
https://www.badcaps.net/forum/attach...2&d=1481341030

Not sure what you are asking or stating regarding this but let me know if there is another issue looming or I need to be aware of after the CAPACITANCE of CM824.

Thanks for all the help.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

You do have 18V/24V power supply problem.
You need to check the CAPACITANCE of CM824.

From the Sticky on troubleshooting:

1) Bad Capacitors
--------------------

Capacitors die from age, heat, and shoddy build quality. Capacitors DO NOT have to be visibly bad in order to bad. They can be out
of tolerance uF (a 1000uF outputs 400uF) and high ESR (ohm). A multimeter will be insufficient to test for ESR. You need an ESR tester for test for ESR.

Not having an ESR is replacing it really the only way to go or should I toss in the towel and call it quits? If replacing is no worse then other Caps then let me know what I should be looking to buy?

Thanks again.

[budm]

Re: Samsung SyncMaster 2693hm - Dead backlight

That cap only needs to be tested for capacitance.
You can buy an new board if you do not want to buy more tool or just replace cap and see if it will fix the problem or not.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

That cap only needs to be tested for capacitance.
You can buy an new board if you do not want to buy more tool or just replace cap and see if it will fix the problem or not.

I am happy to replace the cap presuming it is not a problem to find and remove. I just did not know how to test and the limited use of buying tester going forward was my hesitation.

Anyway, if cap is replaced and still not working would I need to test more caps? I ask since the ESR is not crazy expensive so if I need it I can get one.

Thanks again.

[budm]

Re: Samsung SyncMaster 2693hm - Dead backlight

One think I forget to ask you to check is the DCV between the two legs of the main filter cap (the 450vdc large cap laying on its side), it should have about 380~400vdc.
Be real careful since it is in the hot side of the circuit.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

One think I forget to ask you to check is the DCV between the two legs of the main filter cap (the 450vdc large cap laying on its side), it should have about 380~400vdc.
Be real careful since it is in the hot side of the circuit.

It registered ~312vdc and CM824 ~157vdc.

Let me know next steps and thanks again.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

@budm - If you have given up on this thread (understandable) let me know.

Thanks