CurtPalme.com Home Theater Forum

**Curt Palme** · Posted: Tue Jun 21, 2011 11:19 pm Post subject:

A bit OT, I have another strange problem, NEC PG this time that I sold about 8 years ago. DVDO line doubler, Panasonic DVD player. Customer has put 1600 hours on the set since I put it in.

The set powers up, the menus come up fine, system board locks instantly to the incoming signal, problem is- no picture. Also, no test patterns, but the menus are there. WTF?

Found that the test patterns are indeed there, but you have to look right into the lenses at full brightness to see a faint shadow of them on the tubes.

I changed the system board as that's all I took with me, and chances are I'll upgrade the customer from a plain PG to a PGXtra for about the same price that I'd charge to repair the PG, but now I want to fix it just to know what it is.

My guess is leaky caps on the video output board. I've just never had bad test patterns and video, but perfect menus. Go figure.

As Rosanne Rosanadana used to say: It's always something, if it ain't one thing, it's another.

Oh, and while I was working on the projector ( I really went over to connect the Moome box that he'd ordered), he had to run out to grab a BluRay player, as I didn't tell him that to convert to HDMI, you need an HDMI source. Smile

THat's when I found out the projector had an issue.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

I think I remember seeing something about this when looking over the schematics a while back. I'll look again in a little bit.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Yeah, as I thought the menu is injected into the video out board almost near the end. The test patterns come into the video out board on the same line as the video signal. So I would guess the video out board in the early stage or the gain control board. Since it affects all 3 colors I'd guess probably the gain board or the brightness control from the wave board. The brightness control does not appear to be tied to the menu signal.

So gain or wave board. Maybe video out but doesn't look like it for all 3 colors.

CasetheCorvetteman · Joined: 09 Nov 2008 Posts: 6326 Location: Australia

The video board is pretty much separated into 3 sections isnt it?

**Curt Palme** · Posted: Wed Jun 22, 2011 3:21 am Post subject:

I have had lots of issues lately with the video output board. Caps leak and run down the board...

Right now I'm pissed. Spent the last 4 hours putting a customer's 'mint' tubes into an Ampro 4600... only to find out that all his tubes are super low in emission. Spent 90 minutes making sure that it wasn't something I did while exchanging tubes. His phosphor was slightly better than the ones in it, so I offered to do the swap as part of the deal. sh*t.

CasetheCorvetteman · Joined: 09 Nov 2008 Posts: 6326 Location: Australia

Curt, scotch whiskey fixes that condition you have mate.

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

**Curt Palme** · Posted: Wed Jun 22, 2011 3:38 am Post subject:

Well, I have to say it was deceiving. Tubes look super clean, only the slightest hint of 4:3 wear on his green. Still, I should have powered up his 4300 before pulling the tubes out, and not taking his word that the tubes were mint. My bad, really.

stefuel · Posted: Wed Jun 22, 2011 9:01 am Post subject:

It might be interesting to do a filiment voltage check on a AmPro. All I ever get for wear on my tubes before they go low emission is a slight wear pattern on the green. I do however put a pant-load of hours on my projector on a smaller then normal screen so the contrast setting is reduced.

Tom.W · Joined: 09 Mar 2006 Posts: 6635

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

**Curt Palme** · Posted: Wed Jun 22, 2011 1:48 pm Post subject:

Yes, all that stuff. Once I dropped in an original red tube, the G2 settings went way down, as did contrast and brightness (and subs) and I almost blinded myself when I first turned it on. Smile

Here's another weird one about that 4600.

I went into the color temperature menu when the blue tube was way low in brightness at first to see if the settings there were a mile off. All of a sudden, all three tubes blanked out. After 1/2 hour, I switched to memory location 3, and everything came back. I then went back to memory location 2, and checked:

-sub contrast and brightness
-contrast and brightness
-blanking
-CRT cutoffs.

I could not get the video signal up at all, nor the test patterns. Once I copied memory location 3 to #2, all was well again. Did I miss a setting that would kill the image and test patterns, or did the memory location glitch?

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

**Curt Palme** · Posted: Wed Jun 22, 2011 3:03 pm Post subject:

I will if I inherit the set. I emailed the customer last night to see what he wants to do.

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

I have an 8 inc blue tube here, looks brand new. The HV wire is spotless and the tube bell is still sHiny Silver color from the Anode coating which slowly turns gold then brown with age= No emission. sure wish I had a sencore.
MAc I don;t suppose you would be iuntersting in zapping it for me for a few bucks would ya, old friend. Wink

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

**Curt Palme** · Posted: Wed Jun 22, 2011 11:31 pm Post subject:

OK, the DWIN is in da house! Before I took it away, I cut the fan wires. Still shaking. I took the unit out in the hallway, about 15' away from the HT and plugged it into a different circuit. Still shaking.

Stay tuned!

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Bad deflection yolk maybe, or connection.

**Curt Palme** · Posted: Wed Jun 22, 2011 11:36 pm Post subject:

I changed all the yokes on site already. Trust me on this one, anything I've seen posted here, I've already thought of.

(damn, that sounded conceited, sorry!) Smile

**Curt Palme** · Posted: Thu Jun 23, 2011 12:20 am Post subject:

Youtube clip 1. I'm on the phone with Tim. Smile

The camera is rock steady, the image is shaking.

http://www.youtube.com/watch?v=3rCF1GROK2g

# 2- here you can see twitching of the whole image:

http://www.youtube.com/watch?v=90NBykNujNc