Westinghouse SK-32H240S - blue light, wont turn on

[b0b0]

I snagged this TV off of CL for a decent price. Figured I'd throw new caps on the board and call it good to go. But, as with all things in life, it wasn't that simple.

Pulled the panels off, checked the power board and control board, all the caps look good. I checked the solder joints on the L1 and L2 transformers and both check out. No cold joints there.

Symptoms:

Blue LED lights up
Pressing the power button does nothing.
Slightly humming from a cluster of caps on the 'top' of the power board.
No audio nor picture when power button pressed.

Things Checked:

Caps
Soldier joints
the blue fuses by the main power in check out.


Has anyone repaired this particular TV before? I can get some pretty high def pictures of the board if it will help you seasoned members help me .

[crtfool]

Re: Westinghouse SK-32H240S - blue light, wont turn on

Are the caps in this TV made by Capxon? Did you test the caps? If so, how? If not, then buy good quality Panasonic caps - FM or FC Series and replace them all.

[b0b0]

Re: Westinghouse SK-32H240S - blue light, wont turn on

I have not removed every cap. I'm not sure who makes the caps.

I was testing them with the multimeter - resistance method. Place the tester in a higher 'ohm' setting and it will gradually begin to read resistance. I read that without an ohm reader this is the only way to test the caps.

PS: thanks for the quick reply =)

[crtfool]

Re: Westinghouse SK-32H240S - blue light, wont turn on

You need an ESR meter to measure caps for resistance.

[b0b0]

Re: Westinghouse SK-32H240S - blue light, wont turn on

I was under the impression that you could use the resistance setting of a multimeter to test the capacitor.

By seeing if the resistance stayed at OL or gradually started to climb.

[b0b0]

Re: Westinghouse SK-32H240S - blue light, wont turn on

This is where the hum is coming from.








Caps look good. Guess I should pull all of them and test?

[crtfool]

Re: Westinghouse SK-32H240S - blue light, wont turn on

Replace the 9 capacitors on the power supply, you do not have to replace the very large capacitor - total cost should be about $10 with tax and shipping.

[b0b0]

Re: Westinghouse SK-32H240S - blue light, wont turn on

Alright, I'll replace all the caps.
Thank you for your advice! Beats the heck outa buying a new power supply.

[momaka]

Re: Westinghouse SK-32H240S - blue light, wont turn on

I would say don't replace those caps yet. The caps in your picture are made by Chemicon, likely KY or KZE series. Those are very very reliable.

Post some high-resolution, high-quality, pictures of the top side (covering the whole top side) and the bottom side (again covering the whole bottom side).

I think your power supply may just have an issue, but I'll need some good pictures to tell you what to check.

[b0b0]

Re: Westinghouse SK-32H240S - blue light, wont turn on

Thank you, I haven't ordered the caps yet.
I'll snap a few pictures tonight and post them up.

[ecking767]

Re: Westinghouse SK-32H240S - blue light, wont turn on

I would say don't replace those caps yet. The caps in your picture are made by Chemicon, likely KY or KZE series. Those are very very reliable.

Post some high-resolution, high-quality, pictures of the top side (covering the whole top side) and the bottom side (again covering the whole bottom side).

I think your power supply may just have an issue, but I'll need some good pictures to tell you what to check.

I agree with momka, those caps are very reliable and I see you haven't made any voltage measurement. You need to confirm if your power supply have +24volts (mostly likely) going to the inverter. You will need to find a +24 volt connection on the top side of the power supply and monitor the +24 voltage going to the inverter circuit (if any) while turning on the TV. You can make the measurement off one of the inductor near the caps to confirm if you have +24 volts.


This will tell you if your power supply is bad or the inverter is no working.

[b0b0]

Re: Westinghouse SK-32H240S - blue light, wont turn on

I agree with momka, those caps are very reliable and I see you haven't made any voltage measurement. You need to confirm if your power supply have +24volts (mostly likely) going to the inverter. You will need to find a +24 volt connection on the top side of the power supply and monitor the +24 voltage going to the inverter circuit (if any) while turning on the TV. You can make the measurement off one of the inductor near the caps to confirm if you have +24 volts.


This will tell you if your power supply is bad or the inverter is no working.

Would you be able to edit one of those photos I posted so I know where the inverter is? I searched for a power supply diagram for a while, but I haven't found it for this TV.

Thank you both for the info, got home late but I'll get pics up tomorrow.

[momaka]

Re: Westinghouse SK-32H240S - blue light, wont turn on

Would you be able to edit one of those photos I posted so I know where the inverter is?

2nd and 3rd picture show the inverter transformers. Those supply high voltage to the back lights of the TV (700V to 1000V at sufficiently high currents, so be careful NOT to touch things there when the TV is running!!!).

Leave that circuit aside for now as first we need to check if the power supply is running...
Which brings us to the following: only actual high resolution pictures from top and bottom of the power supply will allow us to see the configuration of this power supply (whether it has a separate stand-by power supply or not, which is the main power supply, etc.). After that is determined, then we can check if appropriate voltages are present. That connector with the multi-color wires is of particular interest. Any labels next to it listing the voltages by any chance?

[b0b0]

Re: Westinghouse SK-32H240S - blue light, wont turn on

2nd and 3rd picture show the inverter transformers. Those supply high voltage to the back lights of the TV (700V to 1000V at sufficiently high currents, so be careful NOT to touch things there when the TV is running!!!).

Leave that circuit aside for now as first we need to check if the power supply is running...
Which brings us to the following: only actual high resolution pictures from top and bottom of the power supply will allow us to see the configuration of this power supply (whether it has a separate stand-by power supply or not, which is the main power supply, etc.). After that is determined, then we can check if appropriate voltages are present. That connector with the multi-color wires is of particular interest. Any labels next to it listing the voltages by any chance?

Here's the only labeling/voltage readings near that connector.


Top half of the top


Bottom half of the top of the board.

[b0b0]

Re: Westinghouse SK-32H240S - blue light, wont turn on

http://i1132.photobucket.com/albums/...7-29123451.jpg

http://i1132.photobucket.com/albums/...7-29123439.jpg

^raw links, higher resolution.

[momaka]

Re: Westinghouse SK-32H240S - blue light, wont turn on

Here's the only labeling/voltage readings near that connector.

Perfect! That's really useful bit of info there.

The first thing to do on TVs like these is to check the stand-by voltage when the TV is plugged in but not turned on. It is usually labeled as "x"STB, "x"SB, "x"VS, "x"VSB, etc. (where "x" is a number - most of the time it's 5V, but occasionally it can also be 12V). In this case, the stand-by voltage should be present on pin 5VS. Measure the voltage between 5VS and ground (the metal case of the TV and any screw holding the power board down is a good ground to use). It should be 5V as the connector suggests. The fact that you get a blue LED on the front of the TV means that it's very likely present.

If it is, try turning ON the TV and measuring the voltage on PWR-ON. This is the power ON signal for the TV. On most TV sets, this voltage will go from 0V from when the TV is OFF to 5V or close when the TV is ON.

If you do get 5V on PWR-ON, check if you have a voltage on the pins labeled "5V" and "12V". Again, all measurements should be taken with respect to ground.

Also, post a picture of the under side of the power supply with all of the traces. It's needed to tell exactly how this power supply works.

[b0b0]

Re: Westinghouse SK-32H240S - blue light, wont turn on

Wow you've been really helpful thank you!
I'll check those pin voltages this evening, and get those pictures of the underside of the board.

Thank you much!

[b0b0]

Re: Westinghouse SK-32H240S - blue light, wont turn on

wow and I'm back.

Those printed power specs all correlate to what my multimeter says.

Closed my browser without bookmarking the site, took FOREVER to go back through my history and find it, sorry about that.

Next troubleshooting step?

[momaka]

Re: Westinghouse SK-32H240S - blue light, wont turn on

Those printed power specs all correlate to what my multimeter says.

So you're getting 5V on the wires for "5VS" and "5VDC" and 12V on the wires for "12V"? If yes, the the power supply is likely working normally.

Try this... try turning on the TV in a dark room. Even though there may not be a picture on the screen, does the screen backlight appear to be on (i.e. is there a slight glow from the dark screen)?

Can you post some pictures of the video/logic board? Maybe also of the under side of the power supply as well?

[budm]

Re: Westinghouse SK-32H240S - blue light, wont turn on

What do you get at the BL_ON pin (Backlight On)? Pin 22 of CN200 as shown on post 14.
Also, what DC voltage do you get at the primary side large DC filter cap (measure at the two pins of the cap), it should be around 165VDC when TV is plugged in, and around 400V when TV is turn on.