CurtPalme.com Home Theater Forum

MrGogo · Joined: 07 Sep 2006 Posts: 21 Location: MTL, QC

Hey Guys,

I'm having a problem with my NEC XG 110LC. I think the problem Curt described here https://www.curtpalme.com/forum_archived/viewtopic.php@t=23067.html may be it.

So yesterday I was using my projector and all was working fine. Had a movie up from my HTPC running at 1280x1024x60hz I switched the input to 800x600x60hz and turned away for a couple minutes. When I looked up the picture was washed out yellowy with blue leaking beyond the image area and it became clear to me that I wasn't getting blue to project properly.

On closer inspection I discovered that the blue tube was indeed the problem. The whole front of the tube face was glowing, I could not make out any raster at all. The whole face of the tube was glowing right up to the edge and it appeared like the glow was coming from the bottom of the tube. (Technically the top of the tube, the units ceiling mounted) I switched inputs a couple of times and eventually it locked on and started to work properly. An hour later I switched inputs again and the problem presented again. At that point I decided to turn it off and go to bed and do some forum investigating.

After reading Curt's post about the possible tube destruction I'm not sure if I should turn it on and take some pictures and post them or not. Given that I did have the projector on for a while without the tube exploding I'm inclined to think that maybe the beam wasn't off the face of the tube hitting the neck in my case. But I figured I'd ask you guys what the best course of action would be. Also does any one know what the tube face or the projected image looks like when the beam goes off the side like Curt's post describes but before the tube explodes?

On a side note. About a year ago my green focus started going, not horribly I just couldn't get the center and edges focused at the same time. Curt indicated it was probably a problem with the focus board and it would probably get worse over time. Someone else suggested I swap the focus leads to the blue with the green to see if it temporarily fixed it. Which it did, I left it that way and used the blue controls to focus the green, since blue focus doesn't affect the image too badly. This may be related I'm not sure.

Thanks for the help!

Brian

**Curt Palme** · Posted: Mon Nov 08, 2010 4:52 pm Post subject:

I believe this is your V board gone bad. DO NOT turn the set on again. Send me the V board and the blue neck board, those are the only two things that can go bad to cause this problem. I can repair either one and test both. The V board should be repaired regardless...

BTW, I may need to change my XG V board repair pricing. The local place that I was buying chips from ran out (thanks to me) and is not getting more in. I therefore need to buy from the only other source I've been able to find that has stock, and my cost has quadrupled on the chips. Sad

Figure on $150 to repair the V board if I can't get more locally.

MrGogo · Joined: 07 Sep 2006 Posts: 21 Location: MTL, QC

Hi Curt,

As always thanks for the prompt response, much appreciated!

So I started to take the projector apart to get the V board out. While I did this I discovered two soldered together diodes melted into the underside of the main cover. (The units ceiling mounted) I searched the visible boards for missing parts and it looks like the diode burned out, melted its solder points and fell onto the lid.

The spot that I think the diodes fell from is on the H-DEF PWD board and marked SG5102, I think thats the source because the solder pads look a bit melted and there is also another set of diodes that look very similar at SG5101 which seem to be cracked.

You can see the diodes that died in the photos. Also the previous owner added a resistor in line with the fan that blows through the big heat sink on the H-DEF PWD board. Maybe this reduced air circulation is what lead to the diodes dying an early death.

So do we still think its the V board or the neck board?

Thanks again!

Brian

**AnalogRocks** · Posted: Tue Nov 09, 2010 3:55 am Post subject:

Have a look at the circuit board in the second picture. It looks cracked under the blue LED(?)

MrGogo · Joined: 07 Sep 2006 Posts: 21 Location: MTL, QC

Good eye AnalogRocks and thanks for the help, but upon closer inspection, the blue LED is actually a blue trimpot and thankfully the board isn't cracked, although it does look a bit like that in the picture, its just a blob of clear silicon or epoxy on the pot so that you can't turn it.

Brian

**AnalogRocks** · Posted: Tue Nov 09, 2010 5:40 am Post subject:

I thought that was a weird place for an LED hence the question mark.

jarseneau · Joined: 06 Nov 2007 Posts: 323 Location: WI

The first 'diode' picture looks to me like one of the spark arrestors that sit at the edge of the HD board just outside the big heatsink. They are very easy to damage if you are 'ham handed' like me when you are swinging up the hinged board assy. They are more likely damaged by the inadvertent hand contact than anything related to other electronic failure. I forget what happens when they are broken. I forget if there's a pair like that for each color but I remember there was more than one so I would be sure to check the edge of the board for others missing/damaged. It wasn't hard to find a replacement at Mouser.com or one of the other parts suppliers.

**Curt Palme** · Posted: Tue Nov 09, 2010 3:34 pm Post subject:

Those are indeed spark gaps and have no relation to the current issue. A few arcs, and those gaps usually blow apart. Solder them back in or leave them out, the set will work fine.

MrGogo · Joined: 07 Sep 2006 Posts: 21 Location: MTL, QC

So theres really no need to replace them? I can't very well put the old ones back they disintegrated when I pulled them out of the lid. I'm encouraged to know its not related to my current issue. So if I choose to replace them does anyone know what the part is called off hand, I looked through the parts manual I have for the projector but never found SG5102. I probably need to look closer its a big list!

So more of a general question then specifically to my set: What causes the spark gaps to arc and break and why didn't those clever NEC engineers know about it and put in some heavier duty parts?

Guess I'm back to pulling the V-board and Neck board.

Thanks again guys

**Curt Palme** · Posted: Tue Nov 09, 2010 4:27 pm Post subject:

I can rob a couple off a parts board here and can throw them into the box once I'm done with the repairs. Put a note in the box to remind me to do so, I don't think you'll find originals at a parts place, I never have.