Curtis lcd3215a Standby power only

[allsmith]

Symptoms=
Red led when plugged into wall
Steady green flashing led when power button is pushed
Steady green flashing led stays after pushing power button to turn off

Visual inspection=
found 2 slightly puffed caps on power supply & heat signs around transformer.

Replaced the 2 caps,symptoms did not change.
I tested for shorts on all large mosfets and bridge rectifier(none found)
Tested for shorts on 4 large diodes (none found)
Tested the 4 rectifiers and all 4 test for a short,But looking at how there in circuit, that could be the way they would test in circuit, but im not sure on that.
I also hunted for a fuse but cannot find one.

I tested for voltages on pins going to main board and to inverter
found 5v on two pins going to main board
(actual voltages on my pics)

Do you guys think the two pins going to the main board that i found 5v on are standby for the main board and a signal voltage coming back from the main board to tell power supply to turn on??

Should i replace the rest of the caps on the power supply??

Should i pull the 4 rectifiers out of circuit to test??(I can post pic of how there in circuit if needed)

I dont know how to test the transformer.

Any help on what i should test next would greatly be apprecieted!!!

[selldoor]

Re: Curtis lcd3215a Standby power only

There looks to be 2 black fuses on the main board top left under the wires

[allsmith]

Re: Curtis lcd3215a Standby power only

There looks to be 2 black fuses on the main board top left under the wires

Good eye!!! Thanks! I never thought to look for fuses on main board.

Both test at 0.08 ohms,meter set on 200 ohm scale

[selldoor]

Re: Curtis lcd3215a Standby power only

Pity - they look ok Is there anything to see on the back of the singed area. Did you check that diode - use diode setting on meter and post results.

[tom66]

Re: Curtis lcd3215a Standby power only

Does ON/OFF (blue wire) change when you press the power button?

[allsmith]

Re: Curtis lcd3215a Standby power only

Pity - they look ok Is there anything to see on the back of the singed area. Did you check that diode - use diode setting on meter and post results.

Diode test=
1/OL one direction
543 in other direction
DMM set to diode test

[allsmith]

Re: Curtis lcd3215a Standby power only

Does ON/OFF (blue wire) change when you press the power button?

Blue wire goes to 0.10v when tv is plugged in. DMM set on 20v

When power button is pushed voltage on blue wire goes to 5.0v

Stays at 5.0 even after hitting power button to turn off

Just seen a post of a you tube video that there is a thermal fuse in some transformers,could that be a possibility?

Not sure how to test transformers

Thanks!

[allsmith]

Re: Curtis lcd3215a Standby power only

Here are pics of the back of the power supply board

[tom66]

Re: Curtis lcd3215a Standby power only

OK, so main board is probably okay, but voltages aren't coming up.

Can you try without the inverters and other 24V cables disconnected?

[tom66]

Re: Curtis lcd3215a Standby power only

Another test - voltage across 450V cap should increase when you press the power button - should be around 400V when running, 165V when "off".

[allsmith]

Re: Curtis lcd3215a Standby power only

OK, so main board is probably okay, but voltages aren't coming up.

Can you try without the inverters and other 24V cables disconnected?

I left the inverter wires and green wires unpluged from power supply

Same test results as before
0.10v when pluged into wall
5.0v after hitting power button

Green led stayed solid on this time

[allsmith]

Re: Curtis lcd3215a Standby power only

Another test - voltage across 450V cap should increase when you press the power button - should be around 400V when running, 165V when "off".

450v cap has 169v with tv off and just plugged in to wall.

379v when power button is pushed to on.

[selldoor]

Re: Curtis lcd3215a Standby power only

Perhaps check the soldering on the transformer the pin just to the left of the third row down of 6 wide ventilation holes looks a bit off and this is in the hot (singed)area.

[allsmith]

Re: Curtis lcd3215a Standby power only

Perhaps check the soldering on the transformer the pin just to the left of the third row down of 6 wide ventilation holes looks a bit off and this is in the hot (singed)area.

It seems to look ok to me.
Here is a close up pic
Thanks!!

[tom66]

Re: Curtis lcd3215a Standby power only

I left the inverter wires and green wires unpluged from power supply

Same test results as before
0.10v when pluged into wall
5.0v after hitting power button

Green led stayed solid on this time

Please can you check if the 24V comes up without the inverter connected.

[allsmith]

Re: Curtis lcd3215a Standby power only

Please can you check if the 24V comes up without the inverter connected.

tested 1.5v at the pins where i disconnected the inverter wires

sorry gotta go to work,be back on here in about 8 hrs

Thanks i really appreciate it!!

[selldoor]

Re: Curtis lcd3215a Standby power only

can you check what voltage you get at each end of the 2 main board fuses
can you post pics of the back of the main board

[allsmith]

Re: Curtis lcd3215a Standby power only

can you check what voltage you get at each end of the 2 main board fuses
can you post pics of the back of the main board

0.00v on all ends when first plugged into wall.

0.40v on all ends when power button hit, but steadily drops to 0.05v on all pins within about 30 seconds.

Meter set to 20v scale

[allsmith]

Re: Curtis lcd3215a Standby power only

Here is a pic of the back of main board

[retiredcaps]

Re: Curtis lcd3215a Standby power only

Steady green flashing led when power button is pushed
I tested for shorts on all large mosfets and bridge rectifier(none found)

Just some general hints for future troubleshooting.

When you get any sort of power LED light (red, green, flashing), that automatically tells you that the 5V standby is working. Since 5V standby is working, there is no need to test the bridge rectifier. If the bridge rectifier were bad, you wouldn't any DC voltage.

Should i pull the 4 rectifiers out of circuit to test??(I can post pic of how there in circuit if needed)

The main board uses the PS_ON pin to tell the rest of the power supply to start. If PS_ON is low, then the power supply will not start.

I dont know how to test the transformer.

The main transformer on the power rarely fails. In order to "properly" test it, you need a special tool called a ring tester. For example,

http://www.anatekcorp.com/bluert.htm