Riddled TV Repair Forum

kuhurdler · Joined: 28 Dec 2006 Posts: 2571 Location: Overland Park, KS

5 V is the standby power. The rest of the supply will not be active unless the TV triggers the triggers it to power on (One of the wires is a feedback wire)

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TonyC1 · Joined: 17 Mar 2009 Posts: 71

With the powersupply in tv & power on & start button pushed (also tried remote) following readings from PS.

CNS1 - o.651 mv DC - supposed to be 5V

CNS2 - 4.2mv DC - supposed to be 18V

CNS3 & 4 - 0 DC - supposed to be 24V

How can I be sure the on/off switch & IR board is sending signal to start? The on/off button is a bit beat up & the "click" of pushing it seems weak compared to the other buttons of the same type on tv - maybe its damaged - any ideas on how to test it?

Thanks,
Tony

JTS1957 · Joined: 21 Jan 2009 Posts: 1331 Location: Far, Far Away

Short momentarily across the switch to test.

Which five volts?

5Vs should be 5 volts Stand-by (there all the time the set is plugged in)
5V should be 5 volts (there with Set Running)

TonyC1 · Joined: 17 Mar 2009 Posts: 71

The standby 5v is ok - but the main 5V of CNS1 that seem to connect to main upper board.

JTS1957 · Joined: 21 Jan 2009 Posts: 1331 Location: Far, Far Away

Your power switch (Keyboard) signal will arrive at the control board. You should be able to observe a change in voltage each time you press "power" (or other key). This same board will have a connector that goes to/from the power supply. One pin of this connector should "turn on" the power supply (allowing the 5V; the 18 volt; and the 24 volt to appear). I couldn't make out the lettering clearly, but it is on CNS1. Monitor these one at a time - one should change with each power button press. If not you could monitor the 5 or 18 or 24 while you try to turn it on with your own voltage. You probably can use the 5 volt standby, but I'd start with a lower voltage external supply if you have one.

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TonyC1 · Joined: 17 Mar 2009 Posts: 71

Sorry for the first pict here is a better one
labels
+5vs

O/F

+5V GND

B-ON GND

BR1 GND

JTS1957 · Joined: 21 Jan 2009 Posts: 1331 Location: Far, Far Away

If BRI is backlight (brightness)...
& B-ON is backlight ON ...
Then I'd hazard to guess that O/F is power supply on/off.

Which one is 5v standby? Probably the +5Vs (unless is 5 volts switched?)

TonyC1 · Joined: 17 Mar 2009 Posts: 71

5VS is only 5Volts I get.

Will try testing other with someone pushing on off buttton.

TonyC1 · Joined: 17 Mar 2009 Posts: 71

The on off switch seems like it doesn't "click" like the other button but if I meter continuity on the two posts on the back its open & then does close temporarily when pushed. Not sure how to check IR. Any ideas on what to check to see if power is flowing to or from this board? Where to place leads to check? Here are picts I hope will help.
Power button is on the left side of botom pict (right in upper)- I flipped it so labels could still be read.

BTW - no reading changes with person pushing button or remote at the PS.

JTS1957 · Joined: 21 Jan 2009 Posts: 1331 Location: Far, Far Away

Clean up the solder side of board and retake pix.
1) "J1" I presume, goes on to rest of keypad and then to Control board?
2) CNS1 goes to same control board?
3) External supply to power on the power supply - 5V/18V/12V work or no (or you didn't try this test)?