LG42PC1D power board swap

[tom66]

Re: LG42PC1D power board swap

It is normal for two relays to click in after each other. There should be two rapid clicks when it turns on, then one or two when it turns off.

[flocko]

Re: LG42PC1D power board swap

That is not what happening with other board i am just getting one click not two is the 68uF 450v cap the problem do you think.

[rayrod81]

Re: LG42PC1D power board swap

It could well be the problem. Most common caps that go bad in my experience are low capacitance-high voltage (like your 68uF 450V) or high capacitance-low voltage (1000uF-3300uF 10V-25V). The low value caps usually dry out and do not bulge. I have seen this many times on Y-sus boards and power supplies.

[flocko]

Re: LG42PC1D power board swap

well i pulled the cap and tested 64.2uF so not bad, maybe i have put a bad one in when i replaced them? still am thinking that the Vs on is were the problem is as it does not come up till the relay drops out

[flocko]

Re: LG42PC1D power board swap

Hi all need a little help from some of you plasma boys, Tom kindly put the alignment guide for my panel 42x3 on post 9, so the phrase full white raster what is that and how do i achieve it?

[tom66]

Re: LG42PC1D power board swap

Menu, ISM Method under one of the submenus, select "WHITE".

[flocko]

Re: LG42PC1D power board swap

Thanks Tom with the white screen have reset all voltages to panel sticker. i have a fair bit of panel flicker what can i do to clear this up or do i have some other problem.

[tom66]

Re: LG42PC1D power board swap

It's normal on full white at a close distance. On ordinary TV the flicker will be mostly unnoticeable. Just a limitation of older plasma displays. Even the Panny 46" I have flickers on full white.

[flocko]

Re: LG42PC1D power board swap

when on full white it seems a little pink and when back on video thats when it flickers and the colours flash.

[tom66]

Re: LG42PC1D power board swap

If it's pink tinged then Vs is probably a little low.

[flocko]

Re: LG42PC1D power board swap

all voltages as panel sticker and new battery in meter -Vy taken across resistor and Vsc across cap i think thats the right way to do it, and the Z-bais test point to chassis same as the Vs and Va,

[tom66]

Re: LG42PC1D power board swap

Vs may need to be tweaked up then beyond panel rating. Max 195V.

[flocko]

Re: LG42PC1D power board swap

the flicker gets better the lower the Vs goes is that a clue as to what could be wrong ,

[tom66]

Re: LG42PC1D power board swap

Sounds like it is power limiting -- can we have a picture of the problem?

[flocko]

Re: LG42PC1D power board swap

Hi Tom Sorry for late reply, Just recalled when i first opened the set to remove the power supply board,i had it on the stand and one of the screws fell out the board into the set, so i took out the main board to find the screw still could not see it,had the control board screws out and lifted that in the end after taking the heat sinks off the bottom i found the screw and replaced everything, i am now thinking that if this set were an LCD i would say it had a T-con or ribbon fault,so am going to check all the plugs and ribbons

[flocko]

Re: LG42PC1D power board swap

photos of white screen with Vs 186v video Vs 186v and with video Vs 172v lowering the Vs cleans up the video. cleaning the ribbons and reseating did not help

[tom66]

Re: LG42PC1D power board swap

Underdiffused. Tweak the RAMP UP and RAMP DOWN controls. If that has no effect, try tweaking -Vy, Vsc and Vzbias. Can't really suggest much else.

[flocko]

Re: LG42PC1D power board swap

with the Vs set to 172v and the low power option on its not to bad, do you think if i were to lower the other voltages by 10% or so would that help ,sorry for all the questions but working on plasmas is all new to me and dont want to damage anything.

[tom66]

Re: LG42PC1D power board swap

170V is very low for an LG. I think there may be an issue with the PFC circuit or otherwise.

[flocko]

Re: LG42PC1D power board swap

Tom what is the PFC circuit and where is it to be found ? how can i check it