Never seen this part before. What is it ?

Thread Starter

Externet

Joined Nov 29, 2005
2,240
Hi. Labeled SP803 on the board, translucent plasticky yellowish look, surface mount, full continuity.

It is in series with backlight LEDs driven supply in a TV at around 100V. The + path marked red.

P1010667.JPG
 

Thread Starter

Externet

Joined Nov 29, 2005
2,240
This is weird. There is another on the same board, labeled SP801. Connected to nowhere. Just soldered on its pads with no vias nor anything on the top side.

Picture is horrible:oops:, same part 3mm x 3mm x 2mm at center. They are not tall enough to be "Standoff, Plastic" The board uses an insulating sheet under.

P1010669.JPG
 

jayanthd

Joined Jul 4, 2015
945

Thread Starter

Externet

Joined Nov 29, 2005
2,240
:confused: Pads/traces going nowhere, not much inrush to limit there. An almost decent picture, holding a loupe in front of the camera :

P1010682.JPG
 

wayneh

Joined Sep 9, 2010
17,499
... full continuity...
By that you mean low ohms in both directions?

How about Shutdown Protection? Something that melts at a certain temperature. The unconnected one would indicate overheat to the PCB from off-board heat source.

Grabbing at straws, I admit.
 

SLK001

Joined Nov 29, 2011
1,549
I believe that they are indeed Standoffs, Plastic. The one with full continuity is because the trace underneath is connected to both pads (the part is placed on a trace). They may be there for compliance standards, to insure that the traces are kept at a minimum distance from other objects.
 

Thread Starter

Externet

Joined Nov 29, 2005
2,240
Giving up. Single sided board. This is the top side. Both mystery parts are bidirectional full continuity. The unconnected one is under "eyelet size" marking left of the third '100uF' brown large electrolytic.

Thank you for your patience, fellows.
 

jayanthd

Joined Jul 4, 2015
945
Giving up. Single sided board. This is the top side. Both mystery parts are bidirectional full continuity. The unconnected one is under "eyelet size" marking left of the third '100uF' brown large electrolytic.

Thank you for your patience, fellows.
I see large Capacitor in SMPS circuit. Fuse, MOV, line chokes, Bridge rectifier diodes, SMPS transformer,. Is this only power supply board ?

I guess the Green component like MOV is NTC.
 

Thread Starter

Externet

Joined Nov 29, 2005
2,240
...Is this only power supply board ?...
Yes. It is a Samsung TV. White connector by bottom right supplies to LED backlights. Black connector by top right supplies 13V to main board and gets PWM (brightness?) and turn-on signals and whoknows what else.
Did not find a service manual to see the parts description/bill of materials.
 

AnalogKid

Joined Aug 1, 2013
11,194
Looks like a power factor corrected switcher, although with only 100 uF of bulk capacitance it isn't a very big one. But the layout is weird for that, and there is only one power device. Hmmm ...

ak
 

jayanthd

Joined Jul 4, 2015
945
Looks like a power factor corrected switcher, although with only 100 uF of bulk capacitance it isn't a very big one. But the layout is weird for that, and there is only one power device. Hmmm ...

ak
Yes, the single mosfet must be for power factor correction circuit. It will be in series with the +ve rail.
 
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