Insignia NS-32LCD voltage reading 12vdc

[CLAPTON54]

I need to verify correct output voltage for 12v. 5v and 24v outputs correct. 12v reads 16.7v. Symptom is no pic. I can see white noise on screen with a flashlight. No back light. I don't Want to tear down any further until I confirm power supply is correct. There is a good thread on this,but the voltage question was not answered. Also any other thoughts or tests on correcting this are Appreciated. Thanks for any assistance. - Kevin

[Elysarian]

Re: Insignia NS-32LCD voltage reading 12vdc

is it reading 16.7 with no load? (i.e. just your DMM connected)

If so it may just be poorly regulated (which may also be a fault in itself) and/or reliant on the load to pull the volts down to 12.

[budm]

Re: Insignia NS-32LCD voltage reading 12vdc

Do you have the pictures of the inverter board? Most power supply has the 12v and the 24V to be generated by the same transformer, so I would expect the 24v to be high also since the inverter is not on, so basisally, no load on the 24v either. The battery for the meter is good, it tends to give higher reading when battery is low. 24V reads OK?
We need to find out if the inverter board is receiving the bl_on and the Dimming signals from the main board or not and if all the fuses checked out OK on the inverter board.

[tom66]

Re: Insignia NS-32LCD voltage reading 12vdc

Don't exclude the possibility it has been mislabelled, as I have encountered this before.

[CLAPTON54]

Re: Insignia NS-32LCD voltage reading 12vdc

No load. 24 Volts Volts good. The 12v is in ribbon cable with 5v and on pin to main board. 12v is marked on main board, not power supply. attached a couple of pictures.

[budm]

Re: Insignia NS-32LCD voltage reading 12vdc

12V is for the audio amplifers, so I will need to see good clear pictures of the inverter board next, report any labeling next to the connectors, I need to see which pin is the BL_ON (or ON/OFF, or I/O, or Inv_ON), and pin for the Dim.

[CLAPTON54]

Re: Insignia NS-32LCD voltage reading 12vdc

Is this what you need to see? When you refer to inverter board is it the Power supply or another board?

[budm]

Re: Insignia NS-32LCD voltage reading 12vdc

It is the big long board under the metal cover, there will be a bundle of the wires between this inverter board and the power supply 24Vdc connector. Looking at the back of the TV, it will on the left side I believe.

[CLAPTON54]

Re: Insignia NS-32LCD voltage reading 12vdc

I was afraid that was the one......I'll have to do some more disassembly. Thanks!

[budm]

Re: Insignia NS-32LCD voltage reading 12vdc

If the board is made by CMO, we will be looking for small black fuse with either '15' or '20' printed on top of the body.
There are many version of inverter board for this model:
http://www.shopjimmy.com/catalogsear...ignia+ns-32lcd

[tom66]

Re: Insignia NS-32LCD voltage reading 12vdc

I worked on a similar model before, "12V" is used by the audio amplifiers and should measure around 16 to 18V.

[CLAPTON54]

Re: Insignia NS-32LCD voltage reading 12vdc

Here are the pictures. It was not as bad as I thought. It is CMO. I will look for fuse. Also included picture of main board and cable to inverter connector ribbon cable. on/off is top pin on board and right pin on main board.

[CLAPTON54]

Re: Insignia NS-32LCD voltage reading 12vdc

Found F5 (labeled 15) just to right of 2nd cap from top. see 3rd picture. No continuity.

[tom66]

Re: Insignia NS-32LCD voltage reading 12vdc

That could easily cause this problem. Replace it and it should work.

[CLAPTON54]

Re: Insignia NS-32LCD voltage reading 12vdc

Again, referring to 3rd picture, the third from top component labeled CMO appears to have discolored. You can see the rings on the input side. Is this a replaceable component? Is this the inverter? Would this cause fuse to blow? Also, where is a source to get a on-board fuse? Or can I use a different style. Board reads .75A/76V.
Thanks-Kevin

[tom66]

Re: Insignia NS-32LCD voltage reading 12vdc

That's probably dried glue or marks from a tool. Usually that fuse is the only fault. However, the devices (transformers) can be replaced if necessary.

These may be easiest to solder, depending on your skills
http://www.ebay.com/itm/10pcs-Littel...item5d35fbb91e

[CLAPTON54]

Re: Insignia NS-32LCD voltage reading 12vdc

All,
Thanks. I shorted out the fuse and the back-light came on and TV works! I'll get a Pico fuse on Monday and all should be good.
Kevin

[techietech2]

Re: Insignia NS-32LCD voltage reading 12vdc

All,
Thanks. I shorted out the fuse and the back-light came on and TV works! I'll get a Pico fuse on Monday and all should be good.
Kevin

HEY, KEVIN,.. I was just reading your post here, and noticed you "shorted out" the fuse, now I am not trying to be a know it all, but what I normally do in a case where I don't have the correct fuse is to take the fuse out of the board and wrap a single piece of my smallest solder (tiny stuff) around the end, then across the fuse in a small loop, then wrap around the other end and plug it back in. I only do this in extremely rare cases, and only after checking the circuitry around and associated with the fuse circuit to be fairly sure it is not shorted.... just my 2 cents worth..

[tom66]

Re: Insignia NS-32LCD voltage reading 12vdc

A small piece of wire is not going to act as an adequate fuse, there will be little difference to blobbing it all with solder. However it's not ideal to short it out like you said, more can go bad.

[techietech2]

Re: Insignia NS-32LCD voltage reading 12vdc

yea, you are absolutely correct, and I normally won't even do that. I should have read the entire post and looked at the pics a little closer. (pico fuse)... not a plug in :-) I still dont like the results that shorting it out can deliver. WOW, tv's sure are different now, I haven't worked on them since the late 80's. I am having to learn a lot about the circuitry, and how everything interfaces together. They are just about a computer with a large screen now.