CurtPalme.com Home Theater Forum

amigaman

Hello all.

So here's a strange one. My XG-751 refuses to sync up to both 480i and 480p, but only on the RGBHV and Moome card (component input). The composite input works just fine (with 480i of course). 720p, 1080i, and 1080p work fine on both the internal RGBHV and the Moome card.

Last week I was able to add presets for 480i via RGBHV and it worked great. Got a clean, stable image. But today, neither my old presets nor new signal entries work in SD/ED resolutions. The problem seems to come and go, since I recall issues with it a month or so ago too.

I tried 5 times to make a new input preset for a 480i signal into the component jacks of my Moome card, and each time the horizontal and vertical frequencies (as indicated by the source info screen in the XG) were different, reading 14.93 to 22.19KHz horizontal, and 48.49 to 65.05Hz vertical. Clearly not right.

Anyone had this issue before? Know which board(s) might be at fault? I'm thinking the vertical and horizontal drive boards are fine, since composite always works great.

Thanks!
-Tom

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

So it wont take a 15.75kHz signal?

amigaman · Posted: Sun Jul 17, 2011 8:55 am Post subject:

Correct. Feeding it 15.75kHz at 59.94Hz (480i), both RGBHV and component, and it won't lock to either. No horizontal or vertical lock, however it's not like it's free-running, as the OSD disappears as well. Like it's trying to sync, but it can't.

My HD signals all run positive sync, and 480i/p run negative sync. The projector should handle both. The source info screen reflects the correct polarity. Not sure if the issue is related to that or not.

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

How does this device connect to the projector?

I get a simular issue if my combined sync is not right, and also if i have the H and V swaped with each other. Combined sync, as in RGB-S should be plugged into the H.

Have you played with the settings inside this projector?

**Curt Palme** · Posted: Sun Jul 17, 2011 1:13 pm Post subject:

Well it has good taste, we don't like SD either:)

See if the video or Svideo input will work with the set. If so, I'd suspect a source issue. If not, then I'd suspect the system board. Strange, because when they have sync issues, it's usually the higher resolutions that don't work right, the lower ones are still solid.

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

This is with the Moome Component/DVI card? if so that explains the issues you're having. The Component/DVI card is a fussy POS. However as Curt has pointed out, usually it wont lock onto the higher resolutions, the lower ones it will without a problem.

My advice is if you can use the built in RGBHV then I would, or you can get a HDMI card for yout XG

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

One more thing. It should lock to a signal even if there is no entry for it. it must lock first and then you can make an entry. If it's not locking, even occasionally then it's not an entry problem.

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

amigaman

amigaman · Posted: Sun Jul 17, 2011 5:13 pm Post subject:

Oh, and I'm very sure it's not a source issue. I tested the component inputs with both my PS2 and HDTV tuner, and I tested the RGBHV with my HDTV tuner via my HDFury 3 (which works fine on 1080i and 720p, just not 480i/p).

Also, the Moome Component/DVI card has mislabeled component inputs. While lettering on the card is in the order Pr, Pb, Y, the colored RCA connectors are in the order green (Y), blue (Pb), red (Pr). I determined it is the colors that are correct, as I was able to get a clean image via 1080i component that way. Just a strange thing.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

amigaman · Posted: Mon Jul 18, 2011 5:36 am Post subject:

Reseated all the boards with no luck. Same problem. Just to verify my signal is good, I connected the Y channel of my component source to the composite input, and it synced up fine there.

Should I keep looking into the system board? I don't see any leaky/bulging electrolytic capacitors, but I know both those and the tantalum caps can go bad.

A service manual would help a lot, if anyone's got one in PDF form...

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

amigaman · Posted: Thu Jul 21, 2011 7:16 am Post subject:

Well it turns out the problem was in the Moome DVI/component card all along. It was leaking sync from one source into the main H/V sync buss, screwing up everything else (well, only stuff with negative sync (SD/ED)).

The actual cause of the problem turned out to be the IC the Moome card uses to switch the sync output on and off. While real NEC input cards use relays for this purpose, the Moome card runs both the horizontal and vertical sync twice through a hex inverting Schmitt trigger, and uses the control signal (normally used to activate the relays) to power the chip on and off. No offense to the Moome products, but that is a major design flaw. There are literally dozens of IC's (at least) that are designed to do this correctly, and relays, that would have worked perfectly. Simply cutting the VCC to an IC is unpredictable. My IC had gone bad (it was screwing up the sync throughput as well), but it's still not a great design. Hopefully it's something different in the new Moome cards.

So as a simple fix, I bypassed the IC. Just jumped the sync input pins to the output pins. Of course, I can't have an active input on the Moome card while another RGBHV input is active in the projector, but that's not an issue in my system.

If it was the system or osc board, I would have definitely sent them to Curt for troubleshooting. Just glad I caught this simple and annoying problem before it came to sending parts of my XG away. And at least it was a third party device at fault. I like to have some faith in the reliability of my projector hardware.

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

**Curt Palme** · Posted: Thu Jul 21, 2011 3:19 pm Post subject:

Good call Amigaman, I learned something off this thread..

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

**Curt Palme** · Posted: Thu Jul 21, 2011 4:36 pm Post subject:

Word.

I don't play a lot with Moome cards, so that was news to me, esp. the accurate diagnosis of the exact issue with the Moome card. Good to know.