| Author |
Message |
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Posted: Fri Apr 28, 2017 7:33 pm Post subject: |
|
|
That is IC421 which is a custom programmed CPLD which functions as a DAC controller.
Definitely not a part that can be bought new anywhere.
They seem to fail before 3000 hours of use or they last forever.
All but one of my YA boards has passed the 3000 hour mark so I am inclined to trust them.
|
|
| Back to top |
|
 |
kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
|
|
| Back to top |
|
|
Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
|
| Posted: Fri Apr 28, 2017 9:05 pm Post subject: |
|
|
|
I've had 'that' series of YA chips fail at 55000 hours as well, so there's no rhyme or reason to it. Seems there were a slew that failed between 2007-2010 or so, and everyone had 1500 hours on them, so that's where that theory came into play. I've heard of the last YA IC421 failure maybe 2 years ago? Mind you, I've had maybe 10 G90 issues in the last 2 years only. I know Craig Rounds still has about 50 customers with those sets AFAIK.
|
|
| Back to top |
|
|
km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
|
| Posted: Fri Apr 28, 2017 11:13 pm Post subject: |
|
|
| kal wrote: | Unless you get them for free, I wouldn't stockpile too much however as some of the components degrade over time when not even in use. Electrolytic caps are a great example. Unless someone is handy with a soldering iron and knows how to test them or is willing to shotgun recap an entire board, no point in having too many projectors as 20-30 years from now (possibly less) many of those caps are all going to be long dead.
The good news is that many models were over engineered/built like tanks so they knew the caps would degrade over time such that the units were built for a long MTBF. Ie: overdo the the farads by a factor of 2-3 (assumption is the cap's only used for filtering of course). There's a limit how far you can go however. Some of the higher end CRT projectors that people covet may be over 20 years old. Examples:
Model (year introduced)
Electrohome Marquee (1993)
Sony G70/G90 (1997)
Barco 1209 (1995)
All that to say that you can't expect to put in an nearly unused (or even new) board into a projector 10-20 years from now and expect it to still work. That's even true today to some degree with some models.
Some models have parts that are no longer available too. The Sony G90 Dallas Chip is a good example. Always good to try and have spares of those.
Kal |
Having to support the hobby with some hands on repairs is part of the journey. Its also one driver that will reduce numbers of owners. I am currently starting from the bottom up replacing caps but the upside is a better image quality so you get something for the effort.
|
|
| Back to top |
|
|
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Posted: Sat Apr 29, 2017 12:44 am Post subject: |
|
|
Yeah, actually reverse engineering it would be possible. But it would be rather time consuming as it would require probing out the entire stimulus/response map of the chip whle exercising EVERY control in the projector across its full range, and that includes in ever convergence, focus, and contrast modulation zone as well as 4 pole and 6 pole adjustments and I can barely even start to write the list of what all else is involved.
With a complete stimulus/response map and the data it correlates to, then a flowchart could be developed, and designing the programming for a new CPLD or FPGA could begin.
It's possible but it'd be a LOT of work. I'd need help to do it.
|
|
| Back to top |
|
|
kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
|
| Posted: Sat Apr 29, 2017 12:36 pm Post subject: |
|
|
| km987654 wrote: | | Having to support the hobby with some hands on repairs is part of the journey. Its also one driver that will reduce numbers of owners. I am currently starting from the bottom up replacing caps but the upside is a better image quality so you get something for the effort. |
Yup! I suppose one of the good things about hoarding units is that they stay out of landfills. Even if there's only a remote to slim chance that the projector (or part of it) gets used, it's better than it ending up in a dumpster.
| cmjohnson wrote: | | Yeah, actually reverse engineering it would be possible ... It's possible but it'd be a LOT of work. I'd need help to do it. |
Who do you have signed up so far? How big's the team? (You mentioned 4 months ago in the link above that you 'had formed a small team'). How's the mapping going so far? You're right that it would seem like a massive undertaking.
Kal
_________________
Support our site by using our affiliate links. We thank you!
My basement/HT/bar/brewery build 2.0
|
|
| Back to top |
|
|
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Posted: Sat Apr 29, 2017 1:30 pm Post subject: |
|
|
Four people are on board, at least by verbal agreement, to provide help in one way or another.
Actually getting things moving is a bit of a chore, though.
|
|
| Back to top |
|
|
garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
|
| Posted: Sat Apr 29, 2017 2:02 pm Post subject: |
|
|
| kal wrote: | | I suppose one of the good things about hoarding units is that they stay out of landfills. Even if there's only a remote to slim chance that the projector (or part of it) gets used, it's better than it ending up in a dumpster. |
Yeah, but it's just delaying the inevitable. They'll end up there sooner or later. It kind of reminds me of elementary-school art teachers "recycling" trash for their kids to make art.  The soda bottles or whatever are diverted from the landfill for a little while, but just until mom & dad get tired of all the masterpieces and pitch 'em.
On the other hand, if you buy & use old CRTs instead of going through a couple of digitals in the same time, you actually have reduced waste by reducing the market demand for those products, and that's a good thing. My 15-yr-old Saab only gets about 23 city / 29 hwy mileage. A new Prius would save gas. But by continuing to drive my faithful old Saab, I *didn't* buy a new car, and that's a vastly bigger ecological savings than reducing my gas consumption.
Of course that reduces market demand which has ripple effects on the economy, so no answer is perfect.
|
|
| Back to top |
|
|
Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
|
| Posted: Sat Apr 29, 2017 2:14 pm Post subject: |
|
|
Feel free to try, Chris, but if you look at that massive IC421 thread back when this forum had a pile more members on it, a couple of engineers tried to reverse engineer it, and failed after giving it a good shot. Most of it is detailed in that thread. It's just too complex of a chip to be worth doing.
Heck, even if you made up a board or chip successfully, how many people would buy it? 10? 20?
|
|
| Back to top |
|
|
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Posted: Sat Apr 29, 2017 2:52 pm Post subject: |
|
|
There are things I'm not going to say on an open forum. I will say that more work has been done on this project
than is public knowledge. There's just no reason to get into any details here.
It may never happen. Do all involved want to put the effort into it before it's really and truly too late? Is it already too late?
How much is it worth today to fix a G90 with a sick IC421 chip and no other problems?
|
|
| Back to top |
|
|
Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
|
| Posted: Sat Apr 29, 2017 3:41 pm Post subject: |
|
|
|
$600-$1000, depending on the client. I'd say of the 50 or so G90s I have out in the field though, I'd guess 50% would switch to digital at this point if they had to get this repair done.
|
|
| Back to top |
|
|
kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
|
| Posted: Sat Apr 29, 2017 6:17 pm Post subject: |
|
|
| cmjohnson wrote: | | How much is it worth today to fix a G90 with a sick IC421 chip and no other problems? |
To most people, probably close to $0 given that people are hoarding the units / able to find them for probably close to free. That's this crowd, the people that would be reading this message. Curt has a good point that if you're someone who's got one installed and simply has a guy they call for all things CRT (like Curt), these customers would actually be willing to spend the money. I think if a solution was offered, the only customers would be installers like Curt and Craig Rounds. That said, I'm sure Craig would get his for free given that he's probably one of the four. 
Kal
_________________
Support our site by using our affiliate links. We thank you!
My basement/HT/bar/brewery build 2.0
Last edited by kal on Sat Apr 29, 2017 8:20 pm; edited 1 time in total
|
|
| Back to top |
|
|
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Posted: Sat Apr 29, 2017 7:18 pm Post subject: |
|
|
As long as it doesn't end up costing me more than "play money" I'd be happy just to be part of a team that came up with a fix for the problem. Finding solutions to problems is kind of a hobby of mine.
I'll reveal more when there's more to be revealed. Since I doubt that there's any significant finanical upside to this project,
I don't really have any reason to hold back but I can't be giving out misinformation, either. So since there's really nothing to
declare about it yet, I choose to make no declarations.
You are of course free to speculate on whom may be involved in this project, such as it is. I will neither confirm nor deny it.
|
|
| Back to top |
|
|
kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
|
|
| Back to top |
|
|
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Posted: Sat Apr 29, 2017 8:25 pm Post subject: |
|
|
|
Some of them don't want to be identified. So I'll respect their wishes.
|
|
| Back to top |
|
|
jbltecnicspro
Joined: 23 Apr 2016
Posts: 512
|
| Posted: Sat Apr 29, 2017 8:39 pm Post subject: |
|
|
| cmjohnson wrote: | As long as it doesn't end up costing me more than "play money" I'd be happy just to be part of a team that came up with a fix for the problem. Finding solutions to problems is kind of a hobby of mine.
I'll reveal more when there's more to be revealed. Since I doubt that there's any significant finanical upside to this project,
I don't really have any reason to hold back but I can't be giving out misinformation, either. So since there's really nothing to
declare about it yet, I choose to make no declarations.
You are of course free to speculate on whom may be involved in this project, such as it is. I will neither confirm nor deny it. |
So in other words, you ain't saying nothing until it's over and done with.  I can totally respect that. God forbid the problem doesn't get solved and you drum up a lot of fanfare for nothing (I'm guilty for doing that myself). I hope that you guys are successful though. At the very least the geek in me is very intrigued.
|
|
| Back to top |
|
|
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Posted: Sat Apr 29, 2017 11:30 pm Post subject: |
|
|
|
Yeah, I don't want to raise hopes TOO MUCH and end up failing to deliver anything.
|
|
| Back to top |
|
|
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Posted: Sun Apr 30, 2017 12:47 am Post subject: |
|
|
So this afternoon I watched Rogue One on both my JVC RS45 and my Marquee which is still the one that's been hanging in my HT room for some time. This particular one is running LUG tubes but all STOCK boards, as I decided to use my MP modded boards set
in a newer chassis with fewer hours on it, and having gone through a full refurbishment.
So it's a stock machine other than the LUG tubes.
It seems that there's always something I can tweak a bit better and make it just that much sharper, and being able to directly compare it and map its picture to that of the digital projector's image has solved every geometry problem. It also gives me a reference for sharpness.
After juggling focus and electronic astig yet again, I am truly seeing a level of detail and sharpness that stands up to direct comparison with the RS45, at 1080p. There really isn't any difference in sharpness that can be seen.
There's a difference in color balance and in grey scale, but nothing major and I can't do a lot about that at the moment as my only means of color calibration is somewhere in my house but I'm not quite sure where that is.
At 4K digital projectors can leave CRTs lacking for fine detail, but at 1080p and tweaked to the ultimate level, a stock LUG equipped Marquee can equal a 1080p digital projector. It gives me really no reason to turn the RS45 on except for watching content that I don't want to run on CRTs due to image burn issues. Like playing games or watching network TV channels with their everpresent watermarks or information bars on the top and bottom of the screen.
I've always reserved my CRT projector for watching only movies. That isn't about to change.
|
|
| Back to top |
|
|
kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
|
| Posted: Sun Apr 30, 2017 2:31 pm Post subject: |
|
|
| cmjohnson wrote: | | There's a difference in color balance and in grey scale, but nothing major and I can't do a lot about that at the moment .... |
But until you actually calibrate both, comparisons on picture quality are somewhat meaningless.
For example, it may be that your Marquee greyscale/colour/gamma has giant room for improvement while the RS45's greyscale/colour/gamma is actually as good as it can get. If you were to calibrate both, the Marquee with the huge room for improvement may jump leaps and bounds over the RS45 which is already as good as it can get.
The fact that they look in the same now without any sort of calibration tells you nothing about potential or which is better. It's a useless comparison.
That's like me saying that a Ferrari with a Honda Civic have identical performance when the only comparison I did was drive them 1 mile to the grocery store and back doing the 30 MPH speed limit and never getting out of 1st gear, and concluding they are "the same" because I didn't notice any differences.
Kal
_________________
Support our site by using our affiliate links. We thank you!
My basement/HT/bar/brewery build 2.0
|
|
| Back to top |
|
|
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Posted: Sun Apr 30, 2017 2:42 pm Post subject: |
|
|
It's not a useless comparison because the focus of it was not on color balance or gamma tracking, but on SHARPNESS.
In that respect I found that I could fine tune the Marquee to be sharp enough that you would be hard pressed to tell which
projector you were seeing based on the sharpness and crispness of the image.
It is not intended to be a "cut from whole cloth" comparison. Just sharpness, at this point. And the Marquee can make that comparison a tie.
|
|
| Back to top |
|
|
|
|
