LG42PC1D power board swap

[flocko]

I picked up a LG42PC1D with a broken screen about four weeks ago and have sold the x+y sus on ebay, yesterday on ebay there was a 42PC1D that clicks on then off, One email and a trip to collect and it is now on the table with its back off, This is were my luck runs out the power supply board looks nothing like the one i have spare from the broken set although the connections all match?What would you do stick it in and hope it works, Take a look at the photos and tell me what you think. Thanks for now Flocko

[flocko]

Re: LG42PC1D power board swap

Sorry board number in the set is 6709900019A my spare is 6709900023A i have looked on ebay and the boards from the US show both types with the 6709900023A number?

[tom66]

Re: LG42PC1D power board swap

I have seen both boards used in LG plasma TVs. The one you see there is much nicer -- and an earlier revision -- made by Sanken I believe. They then swapped to the other design, which was made by LG and uses crappy Samwha caps etc.

You can swap them across if all the output voltages and connections match.

[flocko]

Re: LG42PC1D power board swap

Thanks Tom thats just what i was about to do, All the voltage are the same with the new board the amps are higher Flocko

[flocko]

Re: LG42PC1D power board swap

Set powers on but will not let me retune it keep asking for pass code, if i go to the factory reset option on the menu to turn off or reset pass code it just stops me and asks for the pass code? have done the menu on set menu on remote but i dont know how to reset it there anyone?

[flocko]

Re: LG42PC1D power board swap

Just for reference a code of 7777 will default the code lock,Ok now have all tuned in with bit of screen flashing, Screen sticker gives Va 60v / Vs 186v +- 5.2v actual setting Va 56v vs 175v if i adjust the Vs up the flashing gets worst and washed out if i bring down the voltage to its lowest 164v the picture gets better but still flashes a little.

[tom66]

Re: LG42PC1D power board swap

Check -Vy and Vsc on the Y-sustain board, and Vzbias on the Z-sustain board.

You need to set Vs & Va to the panel sticker rating then tackle the other three voltages.

[flocko]

Re: LG42PC1D power board swap

Thanks Tom i think i have found -Vy on Y sus on a resistor on the bottom of the board what voltage should i see here and is it adjusted on the small stand off board, have found Vz bias will take some photos and put up.

[tom66]

Re: LG42PC1D power board swap

Does this set have a PDP42X3 panel? I think it does as I worked on this one before.

Alignment guide (many panels including 42X2, 42X3, and 42X4):
http://www.tgohome.com/ServiceManual...&Search=Submit

Test points are indicated there.

[flocko]

Re: LG42PC1D power board swap

Y sus and Z sus photos showing Vsc and -Vy on Y Sus board and Vz Bias on Z Sus you will have to run me though how to reset the voltages i have not had to do this before ( i have reset the Va and Vs voltages to the spec on the sticker) thanks for all your help. Flocko

[flocko]

Re: LG42PC1D power board swap

Hi Tom do i need to set these in any order ie will one effect the other or not

[tom66]

Re: LG42PC1D power board swap

They are all independent, first check them against panel ratings.

[flocko]

Re: LG42PC1D power board swap

Hi Tom having trouble hitting these voltage Vy wont go under 235v dont no why but i did a low voltage test and they are all reading low 3.3v =2.8 12v =11.8 might be a good time for a new meter battery, I will go over the old power board and pull the caps and test them later will let you know what i find Thanks again for your help Flocko

[flocko]

Re: LG42PC1D power board swap

Hi Tom I have been looking over the two power boards again and have just seen the old one 6709900019A has a 3.3v output the other 6709900023A the output is 3.4v would you think this would give a problem

[tom66]

Re: LG42PC1D power board swap

I don't think so. It's just a nominal voltage, it's usually got a tolerance of around ±0.15V anyway.

[flocko]

Re: LG42PC1D power board swap

Well i think i have the answer can a 6709900023A be used as a replacement for a 6709900019A Yes and No. Yes it will work but not very well, all the voltages are right the plugs all match and the set will run,you can adjust the Va+ Vs but the picture is bad.
Why the No then, the set the 6709900023A came from was a LG42PC1Dv and the set it was going in is a LG42PC1D and is a higher definition so need more power(amps) to drive it, not on the Va/Vs as you would think but on the 19v supply. The boards would be a good swap the other way round though, but dont tell anyone as mine is going back on ebay and is the only one on there.So will now set about changing all the caps and checking the faulty board. Thank again to Tom for his help with this Flocko

[flocko]

Re: LG42PC1D power board swap

well after fiting all new caps the power board is back in the set, when you power up we go from red to blue the relay clicks in and after 3sec drop out and back to red light. with the relay in i have the following
12v=11.9
3.4v=3.42
6v=5.9
19v=19.2
Vs on is .04v in standby and with the relay on, as the relay clicks off it jumps up to 4.75v before dropping back to.04v
Sb 5v=4.9v in standby 4.9v with relay click on
RL on=0.04v " " 4,72v " "
Ac det 4.85v " " 4.82v " "
Vs rises to about 160v before falling back
Va . " " 56v " "
The only caps not yet changed are the 68uF 450v and the two large 270uF 450v on the primary side, the two 280uF 250v, 1 know it has to be some thing on the power supply as it all worked with the other board will order 68uF 450 cap today what do you think

[tom66]

Re: LG42PC1D power board swap

You may have the same issue as the 50PC1D I am working on.

[flocko]

Re: LG42PC1D power board swap

Hi Tom The Vs (on) is not right the voltage does not come up till the relay drops out, as if it is not building fast enough, as i say have almost changed all the caps on the board, but as you do just put them in and did not test any, what is the board number your working on?

[flocko]

Re: LG42PC1D power board swap

Just put the other board back to check Vs on voltage and with this in you get two clicks one relay comes in then the second so my well be the 68uF 450v cap that failed will pull it and test it with my cap tester.