Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

[BigJon119]

This TV was given to me by a friend a few months ago. After spending countless hours pulled in many directed reading different things and trying to figure this beast out I figured I would ask for help here. I know this is not the best starting point, but I do not know which direction to go in next. If someone could point me in the right direction I would greatly appreciate it.

The TV is a Insignia NS-LCD42HD and is a 2007 model. I cannot find anything for it manual wise as everything I find as well as talk is the -09 Model and I read on here that the -09 is the year. The -09 model power supply appears to be different (to me) so I have had issues trying to figure it out.

Problem - Will not turn on, No lights of any kind, No sounds, nothing. (friend told me that during a storm lights flickered and did not have it hook up to power strip) been dead since.

I attached some pictures showing the voltages I was getting. The PS appears to be getting good power from the main line, but I am getting nothing on the Cold Side? Correct me if I am wrong but I think that is what that side is called. I enclosed a picture showing what I am seeing on my voltmeter. The right side has power and the left does not, however I was able to see a very small amount of voltage in some of the capacitors on the left side.

Since I am getting no lights I have read that it needs 5v in standby. I saw that Bad capacitors could be a cause and have checked with a magnifying glass and everything looks fine. I also read that it could be shorted diodes or transistors on the DC output side, the side that I think is the cold side and I am getting very little if any power to. I could check the voltage regulators on the main board, but if there is no power at all going to the MB (all voltage reading from the supply board connectors 5v,PSON,24V,12V, etc were 0v) how would it know to turn the rest of the power on? Obviously I am new and know very little but would really appreciate any advice on what to test / try next. I attached picture of the PSU as well and if you need better closeups please let me know.

[tom66]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

When testing voltages on a power supply, your ground is always the chassis - like the back metal plate.

[BigJon119]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

I remembered doing both a while back when I was looking at it but I went ahead and re-tested with my ground on the chassis to make 100% sure. Sure enough, everything was the same. Thanks for clarifying that for me tom66. That does make sense that you should use the chassis when working on a power supply. Thanks for the tip! I'll be sure to do that from now on

[ben7]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

The mains side will be isolated from the chassis. Try measuring the voltage on the big filter capacitor on the power supply. It will probably be a 200-400V cap.

[BigJon119]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

Thanks for the response ben7, I appreciate it.

Ok I checked the big 450V cap and it measured 380V pretty steady.

*on a side note I waited several seconds between each check and each time the voltage read 700-1000V, but instantly dropped to 379-380V. I don't know if this is because I am using a cheap voltmeter or they are supposed to behave that way. Just thought I would throw that out there in a rare case it means anything.

[tom66]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

If you have 380V, you have PFC and thus usually 5V standby, so please double and triple check your readings as it is very rare for no standby to be output with working PFC because most PFC circuits are powered off the standby circuit.

The spikes are normal on a low cost unshielded multimeter like that. Nothing to worry about.

[BigJon119]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

This is the big filter cap you were taking about right?? It was the biggest one on the board and says its rated 450V MAX on the side. That one measured 380V

*Note* When I measured it all the chords were disconnected besides the main power to the PSU and it was on paper (not grounded by the chassis/screws) if that means anything. I had to measure it this way because I used the leads on the bottom side of the board because it was too hard to get in there and measure it from the top.

If you have 380V, you have PFC and thus usually 5V standby, so please double and triple check your readings as it is very rare for no standby to be output with working PFC because most PFC circuits are powered off the standby circuit.

I double & tripple checked the the readings and there was still no standby voltage. It read 0v each time and to be safe I tested the top of the wire, sides of the connector where the testing points were, removed the connector and tested the pin, and even tested the 5v standby and that entire group on the bottom of the board when I rechecked the cap. (no plugs but main power and not grounded to chassis)

I don't know if this applies but the very common NS-LCD42HD-09 PSU looks considerably different than this one. I don't know if that has to do anything with the 5V standby and PFC or not but thought I would through that out there.

[budm]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

I see you are using the chassis ground as the ground ref point when you are trying to check the voltages on the Primary side, that will not work. The Ground ref point for the primary side is the negative leg of that 450VDC main filter cap. Also do not rely on the heat sink as the ground point, the heat sink on the primary side may be HOT (deadly), do not touch it. Safety Ground which is tied to the chassis inot the ground ref for the Primary side. The Secondary (COLD) side of the power supply is tied to the chassis.
The 5VSTBY is working, otherwise you will not have PFC working. You need to use the pin of the same connector of that 5VSTB pin is on, the GND pin will be the Ground ref point for the Secondary side.
So measure between GND and 5VSB, GND and +5V, GND and +12V, Gnd and ON/OFF.
http://assets.shopjimmy.com/media/ca...461h-top_2.jpg

[senz_90]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

akh.. nevermind. i just thought you are using fault GND reference. budm have explain it all

find information about HOT ground and COLD ground. it has a different way to measure voltage between primary and secondary. be careful on the primary HOT ground !

[BigJon119]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

@budm I tested using the GND pins you mentioned and still nothing on any of the power pins (+5VSB, +5V, +12V, & +24V).

If you have 380V, you have PFC and thus usually 5V standby, so please double and triple check your readings as it is very rare for no standby to be output with working PFC because most PFC circuits are powered off the standby circuit.

Everything I've read for the most part goes along with that, thats why I'm frustrated that I am getting PFC, but nothing on the 5VSB. Only thing I can image is

1. It is not a common issue with the board and one small component went out
   
2. This board is slightly different than other PS (noticed that the NS-LCD42HD-09 information is widely available, but almost impossible to find any on mine older gen LCD42HD. The PS look completely different so idk.
   
3. The problem is there is a short between the keyboard and the chair. (Me)

I made a video of the tests so if any of you see anything wrong I'm doing please let me know. The video confirms the setup I am using, the methods (new ones thanks to this board), and the results of my testing.

http://www.youtube.com/watch?v=hWmhYYun8WY

I figured that taking a little time on my end making a video showing me testing the PS would cut out some of the variables and maybe shine some insight on the matter.

Thanks for the help you guys have already given me, hopefully I can get this TV up and running before Thanksgiving!

[budm]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

"So measure between GND and 5VSB, GND and +5V, GND and +12V, Gnd and ON/OFF" None of those have any voltage then?

[BigJon119]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

"So measure between GND and 5VSB, GND and +5V, GND and +12V, Gnd and ON/OFF" None of those have any voltage then?

sure don't boss. Everyone and everything was saying that I should have power to the 5VSB if I was showing 380V on that big filter cap so I took a video just in case I wasn't doing something just right and even flipped it over and measured the cap and the backside GND to 5VSB, etc just like you described. Nothing on either side.

I've repaired many things but never this depth of a TV circuit board. I found a copy of the service manual for the LS-LCD42HD-09 model and figured I might be able to look at it to help figure it out.

In there it shows the following diagram (attached) and I looked a few up to see what they are.

on box 2 (Check F901, BD901, & C908) (Fuse, Bridge Rectifier Diode, Big Filter Cap)

I know that F901 is good and that the C908 is good. Should I test the Bridge Rectifier Diode and then move down the chart??

I wanted to ask before I tested these because if you look at the 2 boards (attached) they look nothing alike (although that doesn't mean that they don't use most of the same parts and the board is just rearranged)

Am I barking up the wrong tree / wasting my time following that -09 guide?

[budm]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

Boy, I do not know know what else to tell you, when the logic is telling me that something does not make sense, unless I have the board in front of me then I will believe it.You got me on this one.

[BigJon119]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

Do you think I should follow the -09 service manual and test those parts that I listed??

[James Mandapati]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

Hello Moderators,

I have a similar issue (Sanyo LCD 42CA9S) and iam not able to create a new thread.
Would like to create a new thread and post the details

Thanks

[James Mandapati]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

Is this issue resolved?

In your video i see that you measured the voltage across the capacitor in AC range. Should it not be in DC range?

[BigJon119]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

I have put it aside and have been working on doing a full rebuild of a 110cc engine and rewire for my sons go kart. I am almost finished and will be returning to work on this TV in the next 2-3 days.

Was I supposed to check the voltage across the capacitor in DC? I will be sure to remeasure it and post the results.

I will be also testing most of the main components at update those results as well. I bought one of these little component testers and hopefully it will help. Has anyone had any experience using these??




I figure worse case scenario and I will just buy a new power supply....unfortunately my model's PS are ~$60 on eBay, in comparison to the 42LCDHD-09 PS units.

Does anyone know if that model will work for my TV (even if I have to somewhat manually rewire it)???? The -09 models I've seen as cheap at $25 and being a single dad with full custody it would be nice if it did because Im trying to start saving money for my sons college and every penny I can pinch I am. Thanks in advance to any replies.

[James Mandapati]

Re: Insignia NS-LCD42HD No Lights(R,B,G) & No Standby Power

Was I supposed to check the voltage across the capacitor in DC? I will be sure to remeasure it and post the results.

Yes and also check the DC voltage across the bridge rectifier