Old git need help Goodmans LCD TV dead ..

[ceedy]

Trying to maintain my aura of cleverness, in the eyes of my 9 yrs old grandson.

Having repaired a 15in monitor a while back for him by just doing the Caps.
Later doing my own monitor with help from the forum here (caps & a Transformer).

I now have been given his LCD TV, which had just stopped. (Bit of a family heirloom).
So I’m after a clue to maintain my Street Cred LOL.

Tried to buy another board but so far no luck. So looks like its mendy time.

I’ve scratched about on the net and found that this TV a Goodman’s, has the same PSU as a Grundig, ( Grundig Chassis LA2000 ( LCD 51-7401 or LCD 51-7402)).
And downloaded a German/UK PDF of the Circuitry.


LINKY

Found Mains power socket was wobbly with cracked solder. Reflowed but no change its still totally dead.

With my limited kit, there power going around parts of the board but nothing lights up.

Any kind soul got any clues as where to start!

[PlainBill]

Re: Old git need help Goodmans LCD TV dead ..

Trying to maintain my aura of cleverness, in the eyes of my 9 yrs old grandson.

Having repaired a 15in monitor a while back for him by just doing the Caps.
Later doing my own monitor with help from the forum here (caps & a Transformer).

I now have been given his LCD TV, which had just stopped. (Bit of a family heirloom).
So I’m after a clue to maintain my Street Cred

Tried to buy another board but so far no luck. So looks like its mendy time.

I’ve scratched about on the net and found that this TV a Goodman’s, has the same PSU as a Grundig, ( Grundig Chassis LA2000 ( LCD 51-7401 or LCD 51-7402)).
And downloaded a German/UK PDF of the Circuitry.

LINKY

Found Mains power socket was wobbly with cracked solder. Reflowed but no change its still totally dead.

With my limited kit, there power going around parts of the board but nothing lights up.

Any kind soul got any clues as where to start!

Start by using a standard font. Readability counts, cute doesn't.

Next, take a picture of the power supply - from directly overhead, well lit, no flash. Attach it to your next post using 'Manage Attachments' - below the text entry area.

Third, what are the voltages on pins of CN1 on the main board (or the equivalent on the power supply)?

Last, what are the voltages on the pins of U801, U802, U803, U805, U806, and U807?

PlainBill

[ceedy]

Re: Old git need help Goodmans LCD TV dead ..

Hi Thanks for the help ..
PIC... of the samsung board..



AS for voltages there are none on any of the connecting cables ( cn102)
and none on any of the U801 etc .
There is power up to and into the transformer T101.
and also to one side of the 4 pin IC (ic102) below the tranny.

even found a Circuit diag !



Chris

[ceedy]

Re: Old git need help Goodmans LCD TV dead ..

?--?

[cmj21973]

Re: Old git need help Goodmans LCD TV dead ..

It appears as if all the solder leads on this IC chip has been melted.

What is exact Make and Model of monitor?

[retiredcaps]

Re: Old git need help Goodmans LCD TV dead ..

What is the DC voltage across electrolytic cap C109? Is it steady or fluctuating?

[ceedy]

Re: Old git need help Goodmans LCD TV dead ..

It appears as if all the solder leads on this IC chip has been melted.

Nope it just the lighting in the photo ..
The TV just stopped working no drama just went off .

Pic . excuse to get mu USB microscope out again!!

[ceedy]

Re: Old git need help Goodmans LCD TV dead ..

What is the DC voltage across electrolytic cap C109? Is it steady or fluctuating?

its Steady @ 22.30volts

Chris

[cmj21973]

Re: Old git need help Goodmans LCD TV dead ..

Nope it just the lighting in the photo ..
The TV just stopped working no drama just went off .

Pic . excuse to get mu USB microscope out again!!

Ok, good know. How about a photo of the solder/trace side.

[ceedy]

Re: Old git need help Goodmans LCD TV dead ..

Ok, good know. How about a photo of the solder/trace side.

Glad to oblige!! , had to dash out in the rain to get some decent light

Chris

[PlainBill]

Re: Old git need help Goodmans LCD TV dead ..

First, you are one old git who is taking some seriously good pictures. And it doesn't hurt that the designer has a very clean layout.

What is the part number of IC101? That is the SMPS controller and the first suspect.

Also, with AC power disconnected, what is the resistance across C125 (measure it on the bottom of the board)?

PlainBill

[ceedy]

Re: Old git need help Goodmans LCD TV dead ..

First, you are one old git who is taking some seriously good pictures. And it doesn't hurt that the designer has a very clean layout.

What is the part number of IC101? That is the SMPS controller and the first suspect.

Also, with AC power disconnected, what is the resistance across C125 (measure it on the bottom of the board)?

PlainBill

IC101 ... 1200P60 Veho M-scope strikes again .. about the best it can do !!

Resistance across C125 is approx 1.7 meg.


Chris

[retiredcaps]

Re: Old git need help Goodmans LCD TV dead ..

its Steady @ 22.30volts

Hmm, according to the NCP1200 datasheet, Vcc should be less than 16V (max) and typical startup is 11.4V (min 10.3V and max 12.5V).

http://pdf1.alldatasheet.com/datashe...P1200P60G.html

Is C109 and all the other electrolytic caps made by Capxon?

PS. Excellent photos.

[retiredcaps]

Re: Old git need help Goodmans LCD TV dead ..

I forgot to ask what is the DC voltage on pin 6 of NCP1200.

[selldoor]

Re: Old git need help Goodmans LCD TV dead ..

Hi - just an observation & probably irrelevant but is d103 fried or just dusty?.

[ceedy]

Re: Old git need help Goodmans LCD TV dead ..

Hmm, according to the NCP1200 datasheet, Vcc should be less than 16V (max) and typical startup is 11.4V (min 10.3V and max 12.5V).

http://pdf1.alldatasheet.com/datashe...P1200P60G.html

Is C109 and all the other electrolytic caps made by Capxon?

PS. Excellent photos.

Fraid so .. all Are Capxon

C.

[ceedy]

Re: Old git need help Goodmans LCD TV dead ..

Hi - just an observation & probably irrelevant but is d103 fried or just dusty?.

D103 seems Ok clean and seems to test ok .

C.

[ceedy]

Re: Old git need help Goodmans LCD TV dead ..

I forgot to ask what is the DC voltage on pin 6 of NCP1200.

errmm!!! OOps!!!

I think it was 14.5 ish ? well just before I slipped with the probe

Slipped between pin 5 & 6 Crack-- flash... Now its almost zero .. wot a numpty .. probably made it worse !!

[retiredcaps]

Re: Old git need help Goodmans LCD TV dead ..

Now its almost zero

No worries. Let's start over from the beginning.

1) With power off and lcd unplugged, measure the fuse by the AC plug? A good fuse should read less than 1.0 ohms.

2) Test the bridge rectifier (D101) for shorts. With power off and lcd unplugged, measure the resistance between pins 1-2, 1-3, 1-4, 2-3, 2-4, and 3-4. Any reading less than 30 ohms suggests a short and you will have to desolder D101 and retest out of circuit.

3) What is the DC voltage across the big main filter capacitor?

4) What is the DC voltage across C109 (the Capxon)?

5) Capxon has a very poor reputation for quality and reliability here. You will be directed to replace all the Capxon capacitors on your TV with something like Panasonic FR/FM "low ESR" series from digikey/mouser.

6) If you did short out the IC, mouser/digikey has replacements for $1.17 USD. See

http://www.findchips.com/avail?part=+ncp1200p60

[ceedy]

Re: Old git need help Goodmans LCD TV dead ..

Been side lined today by family mini panic , daughters SKY TV box died
they cannot live without TV
Another Caps ( taicon) problem , all replaced for £4 and Its done ..

Now Back on a proper job ....

Main Fuse by power socket . blown.. will have to find another or fit a standard fuse holder as I have stacks of 3.12 amp fuses here.

D101 is ok ..

As for the IC that link seems mainly for the US, I can get similar
NCP1200P40 or NCP1200P100 'S ?? any good ?? ( on fleabay)..
All the same spec except for the frequency 100hz instead of 60hz , maybe not as it seems from the data sheet these are fixed frequency ?

Chris