CurtPalme.com Home Theater Forum

Drew Packard · Joined: 12 Mar 2006 Posts: 43 Location: Monroe, Washington

Ok G90 wizards Very Happy

Picked up a G90 the other day....was told the blue tube had an issue...Get it home and start checking it out.
Here's what I find:

1) it was set for ceiling proj so I set it for desktop and discover that the H and V switch positions disagree with the service manual! ie I have to set V and H switches to "down" "right" for floor/front?????
Is there an error in the service man?

2) image is dancing all over the place, very unstable. First thing I'm thinking is IC421 Sad

I have FULL control over every aspect of adjustments, convergence, focussing, brt/contrast, etc....

3) after trying a bunch of things, I find that if I disconnect all 3 convergence connectors(RGB) the image and test patterns stop dancing/shaking. everything is stable. This has me thinking there is something going on with deflection, like there is a phase problem or something?? makes no sense Or somehow tied in with # 1 above?

4) last issue is all 3 tubes are intermittantly pulsating in output. Going into the bias adjust, it is completely unstable, like G2 is going up and down on all 3?

This set has 7300 hrs and was recently pulled for a large digital upgrade.......

No 1 has me really wondering???

What do you think??

Regards, Drew

**Curt Palme** · Posted: Sun Feb 13, 2011 8:35 pm Post subject:

Where the hell have you been? One of your former customers was looking for you, said your number was disconnected.

Anyways, welcome back! Smile

This MAY indeed be the IC 421 issue, although the one that I had ended up shutting down with random error codes.

Deflection is different than convergence. Did you disconnect the convergence output connectors to the yoke, or the input connectors to the output board? Ultimately everything comes from IC421, but if all other functions work fine aside from convergence, it may well not be the CPU board.

I do have a working G90 here (I think), so worst case, you can always come up with the board and we'll play with it here.

Drew Packard · Joined: 12 Mar 2006 Posts: 43 Location: Monroe, Washington

Hi Curt,

Wonder who the customer was? I got rid of my land line....tired of getting raped by the ph company.

I've read through your "call to arms" IC421 thread a million times.......I don't think it's that??

What the Hell with the defl switches though!!?? I really don't get that. Can you confirm that it's up and left for front/floor projection? I think there's something really crazy going on here......

I disconnected the conv plugs right at the yokes......This is strange as Hell too.......

I'd like to narrow this down a little farther if I can......I looked at all the defl wiring/connectors but most/all of them are keyed so it would be hard to misconnect them?

This was supposedly a working unit for 7000+ hours until recently

Drew

P.S. I check in here and at AVS usually every day for anyone that needs to PM me.....

Drew Packard · Joined: 12 Mar 2006 Posts: 43 Location: Monroe, Washington

Curt,

Just reread your post.....Convergence works fine, it's just that if I disconnect the conv connectors, the image and test patterns are stable......

CIR Engineering · Posted: Sun Feb 13, 2011 10:41 pm Post subject:

Drew Packard · Joined: 12 Mar 2006 Posts: 43 Location: Monroe, Washington

Hi Craig, Thanks for chiming in Very Happy

I thought that if you had all control, it probably wasn't IC421?? Crap!

Can you please confirm that the polarity switches.....up/left is for front/floor? Because I have it at down/right for this
Or could this be related to IC421? This is really bugging me

Is there more to the "call to arms" post for IC421 replacement part? Could you elaborate?

This was the one from Or...I'm pretty close by

Thanks Craig!

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

The polarity switches sound like they are malfunctioning. They are tied directly to the YA board and it is controlled digitally.

Based on your problems you may want to check switch S201 on the YA board and make sure it's not in factory mode. Switch 1 should be on.

Drew Packard · Joined: 12 Mar 2006 Posts: 43 Location: Monroe, Washington

Thanks mac, I'll give it a look. This is driving me crazy??
Drew

**Curt Palme** · Posted: Sun Feb 13, 2011 11:31 pm Post subject:

If it is a bad IC421, that's double bad news, as these were usually failing at 1500-2000 hours for the bad batch, not at 6000 hours +. That means every G90 owner could be effed.

Drew Packard · Joined: 12 Mar 2006 Posts: 43 Location: Monroe, Washington

All 4 switches on S201 are in "on" setting

Is there a master reset I could try here? I don't know how the polarity switc could be screwed like this.

Thanks, Drew

Drew Packard · Joined: 12 Mar 2006 Posts: 43 Location: Monroe, Washington

Curt...I hear ya!

I'm not totally convinced it's IC421 yet?? I have control over everything, and pulling the conv plugs makes it stable! Then the pulsating(which might be the PA Board)?

Drew

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

You can try a reset to factory data. Its in the regular menu.

**Curt Palme** · Posted: Sun Feb 13, 2011 11:39 pm Post subject:

Well, like I said, if you're stuck, feel free to bring it up.

Drew Packard · Joined: 12 Mar 2006 Posts: 43 Location: Monroe, Washington

Mac, Yeah I already tried that last night Sad

I was wondering about something on the YA board?

Drew

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Drew Packard · Joined: 12 Mar 2006 Posts: 43 Location: Monroe, Washington

Thanks Curt.....I'll let you know...finding the time will be tough.
Drew

Drew Packard · Joined: 12 Mar 2006 Posts: 43 Location: Monroe, Washington

I'm thinking about my G70 Rolling Eyes

Had a G2 problem and chased it through the PA board.......

Drew

CIR Engineering · Posted: Mon Feb 14, 2011 1:26 pm Post subject:

I have seen IC421 fail so many times now and there are three ways it fails. Yours is showing the most common type; all controls work, but the image pulsates and jumps all over the screen. The IC421 is sending rogue commands to the geometry, gain, bias, and probably other controls. This is why both the image is jumping and the image is pulsating.

If I were you I would want to trace everything down and verify for sure as well, sure doesn't hurt. However, I have seen this so many times I think I know what you will find. If Curt thinks it prudent, you could send me your YA and I could give it a quick look. Or as he says, just bring it by his place and try it in another G90.

I will check the switches for you later today if I have time.

Looks like I dodged a bullet on this one, but I am very sorry for you Sad

There is a fellow who stops by the forum from time to time who is reverse engineering the IC421. He is a retired Xerox engineer who's job was to reverse engineer competing companies technologies. He has already made good strides on replacing this chip and I am confidently hopeful that he will get a solution. He believes he will solve the problem and the solution will be made available when he gets to the bottom of it. He said he would be starting work on it again this February so I will shoot off an email and see what he thinks right now.

I'll write back,
craigr

CIR Engineering · Posted: Mon Feb 14, 2011 2:56 pm Post subject:

Drew Packard · Joined: 12 Mar 2006 Posts: 43 Location: Monroe, Washington

Craig,

Yeah....that's the first thing I did when I got it home, it IS the bad serial # 421 in here.
Sorry Craig, I don't doubt you at all.....I guess I'm in denial Sad

I was hoping it was not the chip. It must be screwing with the polarity switches somehow also.....??

That is great news about the guy trying to come up with a fix!! Best of luck to him!

Well, after hearing this, I'll be putting this guy off to the side.....I was starting to look at taking my G70 guts and transplanting them into the G90...make a G80 of sorts. Don't think it would be too hard to do.

Thanks guys!

Drew