Samsung SyncMaster 2693hm - Dead backlight

[ensign.fodder]

Short version - person thought their video card was failing since it took the monitor about 15, then 30, then 60 minutes to come on and display an image. They replaced monitor and gave it to me. I have confirmed unit is working "fine" in that the image is displayed but only if you shine a flashlight or other secondary source of light.

I have disassembled the unit to remove inverter board, logic, and power. Visual inspection as expected did not show any visible signs of a problem else I would not need to post here.

There is no other indication of a problem, meaning the power light, switch, controls, and such all work fine.

I have a basic multi-meter, I have a macro lens, I have little time but lots of desire to save this monitor from the junk heap.

I will attach the general pictures of the boards in the next post and await some help. If you want macro pictures of the components, please ask and I will respond when I can.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

Inverter and logic boards.

Power in next post.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

Power board.

[stj]

Re: Samsung SyncMaster 2693hm - Dead backlight

the rubycon caps on the invertor are starting to dome.
ZL's dont last anyway.

the psu looks surprisingly good.!!

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

the rubycon caps on the invertor are starting to dome.
ZL's dont last anyway.

the psu looks surprisingly good.!!

OK - so happy to break out the soldering kit (iron, bulb, wick, etc) and replace those four. Can you provide a better sense of your answer, meaning how are they starting to "dome"? I checked the sticky (A guide on how to troubleshoot 2 seconds to black) and it says you cannot test the caps with a multimeter.

Thank you.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

the rubycon caps on the invertor are starting to dome.
ZL's dont last anyway.

the psu looks surprisingly good.!!

Suggestions on what to order? Amazon Prime so if I can get them there bonus!

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

Amazon Link

Presuming I get shipped what is advertised link to Mouser for product

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

Researching existing caps seem to point to following specs:

Rubycon part number: 35ZL220M8X16
Rated Voltage: 35v
Rated Capacitance: 220uF
Capacitance Tolerance: 20%
Temperature Range: -40 to 105C
Rated Ripple Current: 995
Diameter: 8mm
Height: 16mm

Nichicon replacement:

Voltage Rating DC: 35 VDC
Capacitance: 220 uF
Tolerance: 20 %
Ripple Current: 350 mA
Maximum Operating Temperature: + 85 C
Diameter: 8 mm
Length: 11.5 mm

Summary - Initial Amazon Linked product is not up to task (Temp and Ripple)

[stj]

Re: Samsung SyncMaster 2693hm - Dead backlight

i think you can get free shipping from one of the u.s. suppliers - maybe digikey or mouser.

you dont want to use amazon or ebay because of fakes.
the best caps to use would be something like panasonic FR series.

about "domed", the top of the cap should be either perfectly flat or even slightly curved inward.
any curving outward at all is a sign of pressure building up inside the can.
this will eventually lead to the liquid being pushed out around the leads or the top bursting.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

i think you can get free shipping from one of the u.s. suppliers - maybe digikey or mouser.

you dont want to use amazon or ebay because of fakes.
the best caps to use would be something like panasonic FR series.

about "domed", the top of the cap should be either perfectly flat or even slightly curved inward.
any curving outward at all is a sign of pressure building up inside the can.
this will eventually lead to the liquid being pushed out around the leads or the top bursting.

So per DigiKey the FR series don't have a 35v 220uF model (Link)

Mouser order placed --> Link to item

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

Thanks for the help.

[ensign.fodder]

Next question - How to remove old caps safely?

So the caps are not through hole or similar, but have large globs of solder so I expect some sort of pad or similar underneath. I clipped the existing cap's legs off and was thinking about next step, and thought I would ask two questions.

1) Soften solder and use wick and bulb to remove and free cap leg or just soften solder and embed new leg?
2) If the pad get damaged, how would I know and what can I do about it?

Thanks!

[stj]

Re: Samsung SyncMaster 2693hm - Dead backlight

melt the solder and remove the legs with tweezers,
then remove the solder with a sucker.
put the new caps on and apply new solder.

[ensign.fodder]

Re: Next question - How to remove old caps safely?

If the pad get damaged, how would I know and what can I do about it?

Thanks!

Any thoughts in this? I ask since I have seen some scorching (PCB) around the first one I removed and it did not come out clean. Meaning even with full solder melt it seemed "stuck" to PCB. Once I remove rest of the solder, I am afraid for what I will find. Second leg on same cap did not present same issue. Solder melted and leg came out leaving solder blob in place.

Thanks for all the help.

[stj]

Re: Samsung SyncMaster 2693hm - Dead backlight

the "scorching" is probably flux, try to scrape it a bit with a flat screwdriver.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

the "scorching" is probably flux, try to scrape it a bit with a flat screwdriver.

Did as requested but still not confident that part of the PCB did not come off.

Will post pick in a minute.

I did find the edge that showed copper color and tested conductivity to next pad so I think I have enough to work with but may always be a point of failure.

Of course I have to see if this fixes it in the first place.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

So soldering done, conductivity tests on negative leg of caps done, conductivity tests on positive leg of caps done. Board and connections restored but end result is the same. Caps are in parallel or on a common bus so lighting one of six sets of CCL should be possible but not sure if that happens or control circuitry would prevent.

Let me know what I need to check and I will go forth with multi-meter.

Again, original owner said it was taking longer to "warm" up or was showing a dim image. I can still see content with flashlight. I can play sound out of speakers, and PC detects display.

Travelling 12 out of 14 days till X-mas so may be delayed in responding.

Thanks!

[cpt.charlie]

Re: Samsung SyncMaster 2693hm - Dead backlight

You need to check signals like bl_on and have a look at the inverter controller IC.

[ensign.fodder]

Re: Samsung SyncMaster 2693hm - Dead backlight

You need to check signals like bl_on and have a look at the inverter controller IC.

Sorry for long delay - I am back on this.

Can you provide some detail as to how to, "check signalslike bl_on" and "inverter controller IC"?

Thoughts about this post in the comment by Michael | Apr 13, 2012 7:35 PM
http://blog.whitesites.com/How-to-Fi...97265_blog.htm

[budm]

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.