CurtPalme.com Home Theater Forum

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

Id really like to find out what board is causing this issue so I can fix this thing.

Firstly the buzzing and squealing. I don't care what anyone says, ITS NOT NORMAL.

The sounds come and go depending partly on what is on the screen. Certain brightness levels of images will cause it, and it is usually accompanied by some noisy lines top and bottom of the screen. Its not exactly quiet, and resolution or scanrate has nothing to do with it. Its like as if there is some serious ripple current going around in there somewhere.

Jittering sections of the image. Seems to follow zones, the centre is generally fine and stable, top and bottom usually are also. I noticed today while adjusting digital focus that it has an effect on the distorted lines and to a minor degree the amount of jittering in that zone. I have been made aware that there were revised focus boards, I will post pics below of what is in mine.

None of these issues follow temperature. Doesn't make any difference if the machine is stone cold at 18*C or been running all day and sitting on 32-33*C, nothing changes.

There is no way known they could've possibly come out of the box new like this, no one in their right mind would have accepted that "they just do that".

barclay66 · Posted: Sat Oct 26, 2013 2:50 pm Post subject:

Hi,

Maybe one of the old tricks may help You with this one:

When I had to repair a TV set which produced buzzing and crackling noises I used a small rubber hose (about 1cm in diameter and about 30cm long). I would put one end to my ear and use the other one in order to find out the exact location of the noise's source. By this I found quickly that there was a small transformer and a weak solder Joint that needed some care...

Regards,
barclay66

**AnalogRocks** · Posted: Sat Oct 26, 2013 7:41 pm Post subject:

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

Piezoelectric effect.

Have fun Wink

Nashou

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

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

Well I opened the back cover, the twitching is almost gone...

Buzzing is still there, but seems a lot less with the cover open. A couple pics shortly

km987654 · Posted: Sun Oct 27, 2013 3:17 am Post subject:

I can't see any squeal or buzzing as normal. If it changes with Image changes I am wondering if its a cap. Barclays idea sounds like a way to narrow it down. I think I mentioned before now that Curt and others do replace a bunch of caps on those sets before they sell them.

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

Buzzing and squealing seems to be coming from that big brown block there under the little black cover. It has a small red wire that comes out ( as well as the larger one that goes to the splitter ) and that small red wire seems to go nowhere....

All the green lights are on:

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

km987654 · Posted: Sun Oct 27, 2013 3:20 am Post subject:

That's the EHT.

km987654 · Posted: Sun Oct 27, 2013 3:21 am Post subject:

Sorry the quadrupler the black cover is the EHT.

**Curt Palme** · Posted: Sun Oct 27, 2013 3:25 am Post subject:

Hv issue, SMPS or g2 board is my guess.

km987654 · Posted: Sun Oct 27, 2013 3:26 am Post subject:

As you know that's where your 35kv comes from and the insulation on those does break down. That would certainly cause the sound you are hearing and it would vary with the image.

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

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

What does seem REALLY strange is that the jittering has almost gone completely just by opening the back cover. It is there right from stone cold start up, so I very much doubt it would be heat soak...

There are just 2 or 3 very little jitters there.

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

Will pulling the LIMOPRO board out improve anything? I don't use it and am led to believe it was optional....

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

Here are the voltages at cold start:

ElTopo · Joined: 07 Nov 2006 Posts: 1640

I cannot remember but i haven't seen a small red on mine.

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

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

What is this all about?