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Old 06-06-2012, 05:43 AM   #1
alecjahn
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Default Insignia NS L42Q 10A

The latest mini-head scratcher for my week is the unit described in the title.


The TV turns on, blacklight kicks on, but no picture. Sound works. Typical problem.

My reservations - no blown capacitors, that I can see. And there's plenty of them. Previous owner stated the "video card" was dead. I could believe that... though I also know I've fixed LCDs with the same problem that had bad caps in the PSU, not the logic board.

Is there a good first stop for testing? Front (or side) buttons connect to the mainboard.


I'd post pictures but there isn't much to see unless one wants them for reference. No scorch marks, no popped caps, nothing out of the ordinary. I scoured over it pretty well, I thought. I will at first request.
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Old 06-06-2012, 06:29 AM   #2
vinceroger69
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Default Re: Insignia NS L42Q 10A

fuse on t con board? pictures will help us a lot with help finding your fault
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Old 06-06-2012, 07:24 AM   #3
selldoor
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Default Re: Insignia NS L42Q 10A

Hi yes we will need pictures for reference- they also help future viewers who encounter similar problems or even want to know the colour banding on a popped resistor.
When you say the back light comes on does it stay on so you have a totally white screen?
What is the power led doing during start up to stable position.

Have you tried different sources?
Does the OSD come on?

We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed
http://www.badcaps.net/forum/attachm...1&d=1290283049

http://www.badcaps.net/forum/attachm...7&d=1280167246

It will be useful if you can say a bit about yourself - skills tools etc.
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Old 06-07-2012, 01:59 PM   #4
alecjahn
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Default Re: Insignia NS L42Q 10A

Thanks for your understanding and diplomacy. It means a lot.

No OSD. I assume buttons are doing things behind the blank, -BLACK- backlit screen but I wouldn't know for sure, of course.

The power LED does nothing out of the ordinary. Red when in standby, then promptly a solid blue (where it stays) upon hitting the power button. Then a standard number of seconds later, the backlight kicks on to the black screen.


Pardon the use of a flash on the mainboard, I couldn't get a steady shot otherwise (darn this dark house!) I hope that suffices.
The third picture/board is hidden under the metal shield at the top of the fourth picture, which I supplied so you all can see the wiring/layout.
Attached Images
File Type: jpg IMG_0003.JPG (907.7 KB, 51 views)
File Type: jpg IMG_0004.JPG (711.8 KB, 49 views)
File Type: jpg IMG_0007.JPG (855.1 KB, 50 views)
File Type: jpg IMG_0008.JPG (762.7 KB, 42 views)
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Old 06-07-2012, 02:35 PM   #5
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Default Re: Insignia NS L42Q 10A

Please see the test point as shown in the picture.
Can you also get the LCD panel model number as printed on the sticker?
By the way, I wish the pictures are brighter and in focus.
Attached Images
File Type: jpg T-CON fuse.jpg (196.6 KB, 69 views)
Attached Files
File Type: pdf T-CON fuse.pdf (502.1 KB, 60 views)
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Basic LCD TV and Monitor troubleshooting guides.
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Voltage Regulator (LDO) testing:
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Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl

Tear down pictures : Hit the ">" Show Albums and stories" on the left side
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TV Factory reset codes listing:
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Old 06-07-2012, 02:42 PM   #6
mr.sky
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Default Re: Insignia NS L42Q 10A

Quote:
Originally Posted by budm View Post
Please see the test point as shown in the picture.
Can you also get the LCD panel model number as printed on the sticker?
By the way, I wish the pictures are brighter and in focus.
Budm, not a related question, but I need to know what software
do you use to make the yellow squares and arrows. Very Nice.
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Old 06-07-2012, 03:01 PM   #7
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Default Re: Insignia NS L42Q 10A

I use PDF pro (old version 6, which is really cheap to get) to convert the original jpeg to PDF format so I can put in notes, then I can save it as PDF and also save it as JPEG.
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Old 06-07-2012, 03:29 PM   #8
selldoor
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Default Re: Insignia NS L42Q 10A

I didnt think pics were too bad compared to some we see - I hope its just the fuse. If not can you do pics of the long inverter board either in 2 or 3 shots.
Also can you check the bottom hdmi connector it has reflected oddly in the picture - just check its not a crumpled pin/sheath or whatever bits inside those are called.
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Old 06-07-2012, 04:13 PM   #9
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Default Re: Insignia NS L42Q 10A

Why on earth did the manufacturer use mostly high quality Chemicons on the main board, and then use some crummy Elite and CrapXon on the PSU?! It would work far better the other way around!

Sometimes I wonder what the purchasing people are doing and who put them in charge.
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Old 06-07-2012, 10:08 PM   #10
alecjahn
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Default Re: Insignia NS L42Q 10A

The "Main fuse for T-CON" measured a minute resistance when I set my multimeter on 20k ohms. The [capacitor?] measured something when tested on the same range.
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Old 06-07-2012, 10:33 PM   #11
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Default Re: Insignia NS L42Q 10A

" measured a minute resistance" ??
Try 200 Ohm scale to see what you read, I expect to see less than one Ohm on the fuse.
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Old 06-08-2012, 11:17 AM   #12
alecjahn
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Default Re: Insignia NS L42Q 10A

It definitely did not read anything on the lower settings like the 200ohm scale.

Is it going to be easy to figure out the replacement part? Is it likely that CP5 is also toast?
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Old 06-08-2012, 11:59 AM   #13
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Default Re: Insignia NS L42Q 10A

Yeah, anything more than about 3 ohms on a general purpose DMM is probably bad. Use 200 ohms, if it does not read anything, it is bad. On the other hand, if CP5 measures more than 200 ohms, it is probably good.
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Old 06-08-2012, 12:10 PM   #14
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Default Re: Insignia NS L42Q 10A

So the fuse show no reading, it is open.
@test points 1 & 2 (Capacitor CP5, there are other 4 caps that are in parallel with CP5) should also show very high resistance, I have you check the test point just to be sure that it is not shorted circuits.
So basically, the fuse should read like shorted circuits (less than one Ohm).
The capacitor should read like open circuits or very high resistance since it can have other circuits in parallel with the caps.
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Old 06-08-2012, 12:12 PM   #15
alecjahn
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Default Re: Insignia NS L42Q 10A

Alright. Looks like a fuse, so far, then?
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Old 06-08-2012, 12:17 PM   #16
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Default Re: Insignia NS L42Q 10A

Next thing we need is to find out the value of that fuse, I usually get the spec sheet of the LCD panel and look at the current draw of the T-CON board, you need to look at the sticker on the LCD panel, it should have model number and the revision number on that sticker.
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Old 06-08-2012, 02:57 PM   #17
alecjahn
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Default Re: Insignia NS L42Q 10A

Is that sticker likely the one on the top right-center of my fourth picture?
It says E42RMZNKW3BYNN

The T-CON board has V420H1-C12 printed on the board. Seems like a common piece, and not too pricey, however a fuse replacement would be nearly free in comparison.

The fuse, of course, says nothing to me - "UD".



Upon some searching, I find this TV may, MAY, perhaps be the same as a Hitachi L42A403.

Last edited by alecjahn; 06-08-2012 at 03:09 PM..
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Old 06-08-2012, 03:09 PM   #18
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Default Re: Insignia NS L42Q 10A

Oh boy, your chassis completely cover the whole LCD panel, I will use the T-CON number to find out more info.

OK, I found out what panel is used in your TV:
http://www.shopjimmy.com/cmo-35-d033150-t-con-board.htm

Last edited by budm; 06-08-2012 at 03:11 PM..
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Old 06-08-2012, 03:14 PM   #19
alecjahn
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Default Re: Insignia NS L42Q 10A

http://www.go-gddq.com/upload/2011-0...2109492115.pdf
If it helps, I found a PDF for the Hitachi sister unit, as confirmed in your link. The exploded views look to be identical. I assume just a re-branding.
Though for some reason... they don't identify the T-CON.
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Old 06-08-2012, 03:19 PM   #20
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Default Re: Insignia NS L42Q 10A

Quote:
Originally Posted by alecjahn View Post
Though for some reason... they don't identify the T-CON.
That is because they will use whatever LCD panel they can get the cheapest on the day.
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