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G90 image shaking/moving

 
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mp20748




Joined: 12 Sep 2006
Posts: 5681
Location: Maryland

TV/Projector: 9500LC Ultra / Super 02 and 03 VIM


PostLink    Posted: Fri Nov 03, 2017 10:54 am    Post subject: G90 image shaking/moving Reply with quote


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I've pulled out the G90 and after firing it up, the menu pattern shakes or is moving around on the screen. Sent Craig a picture taking with my phone. He said it's a bad IC421 chip.

This is a first time seen problem by me, and a first time ever seeing it on this projector. It's really hard for me to wrap my mind around a digital chip being able to create that moving image or motion, where it appears the two colors displayed are moving separately from each other.


I'm trying to load the video, that seems to not work taking from my cell phone... I'll try the camera...
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Curt Palme
CRT Tech



Joined: 08 Mar 2006
Posts: 24296
Location: Langley, BC

TV/Projector: All of them!


PostLink    Posted: Fri Nov 03, 2017 2:15 pm    Post subject: Reply with quote

Craig is right, the 421 chip is bad. It goes into internal oscillation, sending random data down the serial line, changing the convergence and geometry settings from 0-254, the extremes of the Sony settings, thus the pulsing pix.
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HaydnG90




Joined: 22 May 2006
Posts: 1335



PostLink    Posted: Fri Nov 03, 2017 3:29 pm    Post subject: Re: G90 image shaking/moving Reply with quote

mp20748 wrote:
I've pulled out the G90 and after firing it up, the menu pattern shakes or is moving around on the screen. Sent Craig a picture taking with my phone. He said it's a bad IC421 chip.

This is a first time seen problem by me, and a first time ever seeing it on this projector. It's really hard for me to wrap my mind around a digital chip being able to create that moving image or motion, where it appears the two colors displayed are moving separately from each other.


I'm trying to load the video, that seems to not work taking from my cell phone... I'll try the camera...


Just be thankful there seem to be plenty of spare replacement YA boards around. When my IC421 blew up I had to wait over a year for a reasonable priced parts donor G90 to come up for sale. The pj has been solid ever since though.
As a matter of interest how many hours on that G90? Chip serial number?
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cmjohnson




Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s


PostLink    Posted: Fri Nov 03, 2017 3:47 pm    Post subject: Reply with quote

IC421 is a DAC controller chip. If it's got some bug in it that's affecting the address range that covers raster centering on, for example, the blue channel, then whatever scrambled/noisy data that's the problem is going to be changing the raster centering via bad data to the appropriate DAC channel.

Anything you can do via the remote goes thru the IC421 chip and thus any function that can be remotely controlled (and maybe some that aren't) can be affected by a whacky IC421.

Sadly there was never quite enough interest in brewing up a CPLD or FPGA device to serve as a repair substitute for a bad IC421. I looked into it, but even data I was told that had already been collected was never sent to me as had been suggested could be done. Not exactly promised, but it could have happened and certain people decided not to for their own reasons.

Too bad, because I've got friends with the full skillset necessary to brew up a replacement if we just had the complete input-output data map to work with. And that map is what I was not able to obtain, though it reportedly exists.
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mp20748




Joined: 12 Sep 2006
Posts: 5681
Location: Maryland

TV/Projector: 9500LC Ultra / Super 02 and 03 VIM


PostLink    Posted: Fri Nov 03, 2017 4:39 pm    Post subject: Re: G90 image shaking/moving Reply with quote

HaydnG90 wrote:

As a matter of interest how many hours on that G90? Chip serial number?


I just tried turning it on for this, and it's not turning back on. Very unlike yesterday, when I turned it off/on several times. Would the chip also cause it to not power back up?
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HaydnG90




Joined: 22 May 2006
Posts: 1335



PostLink    Posted: Fri Nov 03, 2017 5:13 pm    Post subject: Re: G90 image shaking/moving Reply with quote

mp20748 wrote:
HaydnG90 wrote:

As a matter of interest how many hours on that G90? Chip serial number?


I just tried turning it on for this, and it's not turning back on. Very unlike yesterday, when I turned it off/on several times. Would the chip also cause it to not power back up?


IC421 failure on the YA won't cause that problem. Have you checked the fuse. Maybe cycling through on/off has caused it to fail? If fuse is intact and you don't see any error codes the PS is probably bad as a guess.
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Curt Palme
CRT Tech



Joined: 08 Mar 2006
Posts: 24296
Location: Langley, BC

TV/Projector: All of them!


PostLink    Posted: Fri Nov 03, 2017 5:25 pm    Post subject: Reply with quote

Have you changed the Dallas chip to a recent one? If the lithium battery dies in it, you cna spot burn the tubes, or the set will not turn on.
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mp20748




Joined: 12 Sep 2006
Posts: 5681
Location: Maryland

TV/Projector: 9500LC Ultra / Super 02 and 03 VIM


PostLink    Posted: Fri Nov 03, 2017 6:29 pm    Post subject: Reply with quote

Curt Palme wrote:
Have you changed the Dallas chip to a recent one? If the lithium battery dies in it, you cna spot burn the tubes, or the set will not turn on.


Oh great, so I should maybe start with a Dallas Chip. Where can I get one?
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mp20748




Joined: 12 Sep 2006
Posts: 5681
Location: Maryland

TV/Projector: 9500LC Ultra / Super 02 and 03 VIM


PostLink    Posted: Fri Nov 03, 2017 6:31 pm    Post subject: Re: G90 image shaking/moving Reply with quote

HaydnG90 wrote:
If fuse is intact and you don't see any error codes the PS is probably bad as a guess.


No error codes, but think it would be a good idea to change the Dallas chip. If that's not the problem, then I'll need a YA Board based on what I've read so far.
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cmjohnson




Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s


PostLink    Posted: Fri Nov 03, 2017 6:46 pm    Post subject: Reply with quote

https://www.digikey.com/product-detail/en/maxim-integrated/DS1245Y-120/DS1245Y-120-ND/1087327

There's the chip.

Although you COULD just put this new chip in and go, it'd be better to copy the old chip to the new one so you keep all your settings including your serial number. I don't know if you have that programmer capacity but Craig does.
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HaydnG90




Joined: 22 May 2006
Posts: 1335



PostLink    Posted: Fri Nov 03, 2017 6:57 pm    Post subject: Reply with quote

cmjohnson wrote:
https://www.digikey.com/product-detail/en/maxim-integrated/DS1245Y-120/DS1245Y-120-ND/1087327

There's the chip.

Although you COULD just put this new chip in and go, it'd be better to copy the old chip to the new one so you keep all your settings including your serial number. I don't know if you have that programmer capacity but Craig does.


Are you sure the stored data on a failed Dallas chip is recoverable. I thought once the battery dies all info disappears or is corrupted. Worth a try I guess but in Mike's situation I don't see any real benefits making the effort especially if he doesn't have a chip reader.
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cmjohnson




Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s


PostLink    Posted: Fri Nov 03, 2017 7:30 pm    Post subject: Reply with quote

If the shaking is occurring, that's IC421. That's not caused by a failing Dallas memory chip.

Copying over the Dallas chip now can't do any harm. Nor can putting in a new one even without copying.

But the shaking image is probably NOT caused by a failed Dallas chip.

Dallas chips are one thing, IC421 is something different.
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HaydnG90




Joined: 22 May 2006
Posts: 1335



PostLink    Posted: Fri Nov 03, 2017 7:51 pm    Post subject: Reply with quote

Yeah, I know that. The reason why Curt mentioned the failed Dallas chip was for a different problem Mike is experiencing ie his set won't turn on. He may dealing with 2 separate unrelated issues at the moment.
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cmjohnson




Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s


PostLink    Posted: Sat Nov 04, 2017 2:24 pm    Post subject: Reply with quote

That may be the case. I view the Dallas chip replacement as simply eliminating a possible interacting issue.

But I think that more likely there is another issue on the YA board and the symptom does sound like IC421 has decided to take a vacation.
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