Pioneer Elit 1120HD Power Supply issue?

[freakaftr8]

Re: Pioneer Elit 1120HD Power Supply issue?

interesting.. I can only assume there is a short on that lower board then. But 4 blinks points to an X drive DC/DC converter circuit failure.. At least from the manual i'm looking at..

129 seems a bit low still to me. Maybe i'm wrong..

Can you look at the other side of that board where it attaches to the panel. Is there clamp in connections to those ribbons or are they fused to the scan board?

[Boyd1966]

Re: Pioneer Elit 1120HD Power Supply issue?

On each L and U board there is a ribbon in the back that is fused to the boards and covered by a aluminum panel (Xs in picture). There are connectors to each board. The U connector rated 129 (as I said before). The L connector (circled) rated 130 to 150. See pictures.

[freakaftr8]

Re: Pioneer Elit 1120HD Power Supply issue?

Ok so your'e saying the lower board disconnected, showed 129 oh VH testing this point from the upper of course.

And Upper showed 130 to 150 testing VH from the lower board testpoints?

[tom66]

Re: Pioneer Elit 1120HD Power Supply issue?

So whichever board causes the drop in VH when it is connected has a short.

[tom66]

Re: Pioneer Elit 1120HD Power Supply issue?

If the connectors are fused to the panel it will be very hard to repair indeed.
We can hope that it is possible to remove them? Can you get a picture?

[Boyd1966]

Re: Pioneer Elit 1120HD Power Supply issue?

No.... I tested the upper board VH and was 129. I then tested the actual connector that would go to the lower board (circled in picture) and that was 130 to 150. I didn't test VH on the lower board because it is not connected.

[Boyd1966]

Re: Pioneer Elit 1120HD Power Supply issue?

I will see if I can remove the aluminum panel and see where the ribbon goes and if it is fused to the panel.

[Boyd1966]

Re: Pioneer Elit 1120HD Power Supply issue?

The pictures show the ribbons to the L and Y boards and it looks like they are fused to the panel as well.

What about replacing the black square IC scans?

[freakaftr8]

Re: Pioneer Elit 1120HD Power Supply issue?

So the lower board connected in circuit is the one causing the dropout in VH? Sorry got a bit confused a few posts back.

The Scan ICs are replacable, however it is a very tedious and patent process. We need to find out if one or more of those are indeed shorted out

[Boyd1966]

Re: Pioneer Elit 1120HD Power Supply issue?

Yes that is correct. I can test the scan ICs but I don't see how I can in the time before it shuts down.

[freakaftr8]

Re: Pioneer Elit 1120HD Power Supply issue?

I'm not sure about Pioneer because I have never messed with scan boards on this brand before, But on other brands when you disconnect one scan board off of circuit you should still have a power up with only half the panel being driven I'm surprised that it will not drive the panel with 1 board disconnected out of circuit

[freakaftr8]

Re: Pioneer Elit 1120HD Power Supply issue?

What happens if you leave both boards disconnected from the Y sustain? Try powering up with both pulled. Does is stay on?

Maybe it will stay on, maybe it won't if it has some kind of VSUS or VH feedback overcurrent without a path of travel...

[Boyd1966]

Re: Pioneer Elit 1120HD Power Supply issue?

It still shut down

[freakaftr8]

Re: Pioneer Elit 1120HD Power Supply issue?

Maybe try this in OHMS setting on volt meter. This is a setting that looks like a horseshoe. Red probe to where I have the red dot, black probe to where I have the black dot. Read each one of those up-and-down the lines of each scan board

[Boyd1966]

Re: Pioneer Elit 1120HD Power Supply issue?

Should I have everything connected before I do that? Please be specific in ur instructions. I really appreciate everything u guys are doing but I have no idea what I'm doing other than trying to narrow down the cause.

[Boyd1966]

Re: Pioneer Elit 1120HD Power Supply issue?

I wont be able to do it till tomorrow

[freakaftr8]

Re: Pioneer Elit 1120HD Power Supply issue?

You can leave both of the boards disconnected.

[tom66]

Re: Pioneer Elit 1120HD Power Supply issue?

I'm not sure about Pioneer because I have never messed with scan boards on this brand before, But on other brands when you disconnect one scan board off of circuit you should still have a power up with only half the panel being driven I'm surprised that it will not drive the panel with 1 board disconnected out of circuit

It won't because it has a scan protection circuit, it will detect when a scan board is not present.
Also it depends on the panel some scan from upper to lower, others from lower to upper, so if the first board in the chain fails the whole set fails.
It's pretty much identical to LCD gate drivers, when one gate driver dies all subsequent ones die as well. They're just shift registers, but fairly high voltage, rated to around 150V per channel and having about 60-90 channels each.

[tom66]

Re: Pioneer Elit 1120HD Power Supply issue?

You should be able to check from red to black here on ohms.

Check on each of the vias (micro-drill holes) that are exposed, if your meter has continuity it will make it easier because there are at least 300 on one board. You can run it along each contact and listen for a beep. Check all the ones near the plasma panel not just the ones I've highlighted.

A short from the output channel to the floating ground (black) is bad, it means one of the ICs on the scan driver board is bad.

You asked before about floating ground. Well plasma TVs are a bit odd in how they work. The X-electrode driven by the X-main/Z-sustain board is common to all rows. But the Y-electrodes are separate because they contain a row selection signal that needs to be applied to the pixels appropriately.

The plasma Y-main output is swinging all over the place from -200V to +200V, the waveform is kinda complex, but in the middle of this, there's a row selection signal, that is VH, which is applied to one line at a time. So you need to be able to "superimpose" VH (~150V) onto the plasma panel but only one line at a time. That is what the scan / "buffer" ICs do. They do not buffer anything. They are only used to switch between the floating ground and the floating ground + VH signals.

The problem is if VH is shorted by one of these scan ICs then other power supplies on the Y-main will shut down so you will get a distorted image then the TV will turn off due to protection. On some TVs you see no lines selected, on others you see every line selected (vertical lines down screen). Or in the case of this Pioneer it's a kind of partial full discharge of the panel... It depends on the technology.

The long and short of it is sadly if we cannot replace or repair that board then the TV is dead.

[Boyd1966]

Re: Pioneer Elit 1120HD Power Supply issue?

Shawn - What ohm value should I look for and look at the pic of my meter and tell me what ohm setting I should use (2M, 200k, 20k, 2k, or 200).

Tom - Can you clarify "Check on each of the vias (micro-drill holes) that are exposed, if your meter has continuity it will make it easier because there are at least 300 on one board. You can run it along each contact and listen for a beep. Check all the ones near the plasma panel not just the ones I've highlighted."? I see the micro holes but how do I know if my meeter has continuity and which hold for the black probe and which one for red probe? Also is this different than what Freak told me to do?