CurtPalme.com Home Theater Forum

mp20748 · Posted: Wed Nov 18, 2009 12:21 am Post subject:

The VIM was swapped (I loaned him one). His boards was put in my Marquee, and almost every possible noise (RF) producing board was tested here.

The set was also ran without any connections other than the AC cord.

I've had these noise problems before. We had one on one of Williams that was chassis related.

dturco · Posted: Wed Nov 18, 2009 12:32 am Post subject:

Mike is correct. We swapped the VIM awhile ago to a un-modded one and back. And it has been run without the HDMI connected also, the problem persists.

I would also like to thank Mike for all of his help on this, loaning of parts and his time.

Thank you Mike Thumbs Up

Dave

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Are all your Ground straps from your Tube bell housings tot he VNB's connected properly? and all the other Ground straps?

I have seen some Chassis with an extra ground strap going from the HDM heat sink to the Blue tubes Ground straps on the VNB cage or any other metal part of the Blue tube.

The last thing id check is the chips on the clm especially the DPB's U7 chip, for now press down on the chips on a flat even surface, be careful not to press to hard as to bend the board. so the surface and the board must be level. But if you have a IC chip puller pull U7 and clean the contacts and then put it back in , paying attention to orientation.

Nashou

dturco · Posted: Wed Nov 18, 2009 1:20 am Post subject:

All ground straps are on and I have also added a ground strap to the HDM cage like HK-Steve did. I will have to get a chip puller,before I attempt the U7 cleaning.

Are you suggesting another ground from the HDM to chassis, or just the tube metal at the back of the funnel the tube sits in? To install this would mean drilling a hole into the HDM's heatsink and tapping a screw into it, and adding another strap/wire, correct? Or am I misunderstanding?

mhalsan · Joined: 09 Nov 2007 Posts: 146 Location: Astoria, Oregon

I would hear a loud SNAP! and all three tubes would shut off, then come back on in a few seconds. This got to be more and more frequent. I also tried changing this and that, checking HV leads, etc. My problem went away when I replaced a bad Mikron VNB with a factory VNB.

This doesn't sound logical- but it works! I haven't had the problem since. We were never able to repair the VNB, so I left the factory one installed on the blue tube.

Thanks, Mark

dturco · Posted: Wed Nov 18, 2009 2:30 am Post subject:

Thanks for sharing your experience.

With the HV leads completely off, disconnected, would the Neckboards still be able to throw off this level of interference?

mhalsan · Joined: 09 Nov 2007 Posts: 146 Location: Astoria, Oregon

If the interference is due to the high-bandwidth, high-gain action of the video amplifiers on the VNB, disconnecting the high voltage probably wouldn't change anything.

Another suggestion: do you have the factory (metal) case, or an aftermarket fiberglass case? I have noticed static on my cordless phone in the vicinity of the unit now that I have the fiberglass case. The metal one probably provided better shielding.

Thanks, Mark

dturco · Posted: Wed Nov 18, 2009 2:44 am Post subject:

I have the metal case. High bandwidth Neckboards did increase the problem, but the phone thing has been there since I brought it home, just not as bad as now.

Thanks you again Mark.

Dave

dturco · Posted: Wed Nov 18, 2009 2:55 am Post subject:

Can I pull a Neckboard and run the P/J without it installed..... SAFELY? If so how?

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

you should be able to run it for a short time before the HV shut down circuit comes into play, One of the Tech bulletins that adds the 3 or 5? diodes tot he VIM was done to be able to do that. Disconnect a VNB to diagnose problems. So I guess you could start with the Blue and move on down the line. just disconnect the Umbilical cord from the mother board or VNB, which ever is easier to get to.

Scott (TSE) told me this trick when i was trying to figure out a video blanking issue. it was a bad VNB, and right when i figured it out i shorted out my vim while probing it ! Sad

Nashou

mhalsan · Joined: 09 Nov 2007 Posts: 146 Location: Astoria, Oregon

I doubt the projector will start up without all of the boards plugged in. The control module does a self-test on power-up.

It sounds like there's some sort of oscillation / feedback in the video chain. That could cause the wavy lines you mentioned. But, that would've been found by swapping boards, which you've done.

You might try running the projector at a different or very low scan rate- 480i - and see if the interference gets better. If it does, the RF emissions could be coming from the horizontal section. There used to be a phenomenon called Barkhausen oscillation- Perhaps a problem with one of the yokes? I see you already replaced the HDM. This is a far-out guess, but I can't think of anything else you haven't already tried!

Thanks, Mark

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

dturco · Posted: Wed Nov 18, 2009 4:10 am Post subject:

O.K. it does run without the Neckboard installed. 1 At a time. It has no effect on the phone cutting out.

But I think the Video Deflection Board is the culprit. It is humming like mad and when I took the wires off of it they were green with corrosion. I can't figure out why since I used deoxit on them when I did the Bellows. I have cleaned them with isopropyl alcohol and now the phone seems to be staying on. However, now the test grids are whacked out, and the full white field is shaking and rolling.

Mike Parker has suggested the Yokes also... maybe, I sure hope not, thats just not wort the effort unless I do Frankenyokes and I am out of money Crying or Very sad

I mean really out of money . Times is tuff in the land of plenty. Crying or Very sad

I'm tired, I sleepy now, zzzzzz. Thanks for the input guys. Smile

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

ok, clean them really good and also the ribbon cable to the the motherboard. Corrosion sucks, Buy some stabilant22 and give that a try.

Also check the CVA cables too on the back plane. and never take the VDM cables off while the PJ is running.

Athanasios

dturco · Posted: Wed Nov 18, 2009 12:33 pm Post subject:

mp20748 · Posted: Wed Nov 18, 2009 12:54 pm Post subject:

dturco · Posted: Wed Nov 18, 2009 1:04 pm Post subject:

I agree Mike. When you made mention of how the Yoke test would have to be done I immediately said I was not comfortable with that as I knew I could, and probably would, screw something up on the P/J or on me with a serious shock.

I draw the line on those kinds of high risk tests.

I'll call you later today.

dturco · Posted: Fri Nov 20, 2009 3:23 am Post subject:

Herringbone pic.[img][/img] I had to photo shop it to show up here, it's very obvious in person on screen.

**AnalogRocks** · Posted: Fri Nov 20, 2009 4:28 am Post subject:

Do you have a ham radio operator near by?

dturco · Posted: Fri Nov 20, 2009 4:32 am Post subject:

Not that I know of.