DIY gray scale tracking and optical comparator? - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 15 Old 10-16-2000, 08:43 AM - Thread Starter
Member
 
Richard Casto's Avatar
 
Join Date: Sep 2000
Location: Raleigh, NC, USA
Posts: 101
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I found an interesting set of posts (and reposts) authored by Guy Kuo of Ovation Software (makers of AVIA).

Included in the posts are directions for DIY gray scale tracking as well as a home built optical comparator. He acknowledges that it does help you determine your color temp (maybe the home built comparator will get you close to 6400K to start with), but that the gray scale tracking should give you a somewhat flat track for whatever color of white you use.

Obviously you will get better results with a professional calibration, and I know a number of you will suggest doing so, but I think I may want to try this myself.

The instructions are geared toward CRT front projection, but he mentions you might be able to do this with a RPTV (as is my case).

Has anyone tried this?

Here is the link for the curious….
http://www.hometheaterforum.com/uub/...17-000004.html

Richard
Richard Casto is offline  
Sponsored Links
Advertisement
 
post #2 of 15 Old 10-16-2000, 08:45 AM - Thread Starter
Member
 
Richard Casto's Avatar
 
Join Date: Sep 2000
Location: Raleigh, NC, USA
Posts: 101
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Ooops,

One small correction. It should read...

"He acknowledges that it does not help you determine your color temp ..."

Richard
Richard Casto is offline  
post #3 of 15 Old 10-18-2000, 10:38 AM - Thread Starter
Member
 
Richard Casto's Avatar
 
Join Date: Sep 2000
Location: Raleigh, NC, USA
Posts: 101
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
bump
Richard Casto is offline  
post #4 of 15 Old 10-18-2000, 12:38 PM
Advanced Member
 
Andrew Low's Avatar
 
Join Date: Feb 2000
Location: Ontario, Canada
Posts: 885
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Guy Kuo posted a version of that on the AVS Forum as well.
http://www.avsforum.com/ubb/Forum2/HTML/001462.html

I haven't tried it yet - but its on my never ending list of tweaks to perform to my HT setup.

Roo
Andrew Low is offline  
post #5 of 15 Old 10-18-2000, 01:01 PM - Thread Starter
Member
 
Richard Casto's Avatar
 
Join Date: Sep 2000
Location: Raleigh, NC, USA
Posts: 101
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Andrew,

Thanks for the info. It looks like he has refined the method even further. I had a copy of the method from his first post and a revision to the original post. I didn't have a copy of this newer revision.

I sent Guy a private forum message with some questions about how to do it. I hope he sees the message (those private messages are easy to miss) as well as has the time to answer my questions. http://www.avsforum.com/ubb/smile.gif

I am probably going to try this as soon as the wife and our two year old child are out of town for a week visit with relatives. I need a few days (so I can take it slow and get it right) to be able to tear apart the set and not have to worry about complaints from the wife (no TV as well as stuff strewn about the living room) or a small child trying to mess with high voltages.

Richard
Richard Casto is offline  
post #6 of 15 Old 10-19-2000, 06:34 AM
Advanced Member
 
Andrew Low's Avatar
 
Join Date: Feb 2000
Location: Ontario, Canada
Posts: 885
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Richard, if you haven't taken your RPTV apart before.. be very careful. Read up on it first, there are some excellent web resources on taking the screen off an RPTV and doing things like lining the cabinet with black felt to reduce internal reflections.

I don't have an RPTV, but I believe you have to remove the FRONT of the unit (the screen) to access the CRTs inside. If you try to remove the back, you run the risk of dropping the mirror into the screen.

For something like this -- I always call a friend over to help me not make any expensive mistakes..

Roo
Andrew Low is offline  
post #7 of 15 Old 10-19-2000, 07:16 AM - Thread Starter
Member
 
Richard Casto's Avatar
 
Join Date: Sep 2000
Location: Raleigh, NC, USA
Posts: 101
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Andrew,

The service manual should arrive early next week ($48+shipping Ouch! Most Toshibas SM go for $15 but not for the TW40X81?). I have seen numerous warnings about the mirror dropping and tearing the screen. I think it depends upon the make and model if you need to take the screen off to access the CRTs. I believe that for disabling things such as SVM and some other tasks you can get in via the front on a Toshiba. I am not sure about mechanical focus, and other tasks. Some of those may require removing the screen. I am going to take it nice and slow and by the book. I don’t want to...

1) Kill myself
2) Damage the set physically
3) Screw up the sets configuration (i.e. service/design/addr mode parameters) and/or calibration (i.e. adjust the screen VR knob by accident when trying to adjust the focus VR knob)

I have been reading a number of forum posts on various sites as well as various ‘how to’ on a number of sites such as Errol’s/Keohi and other personal HT web pages.

I may wait until the set has a number of hours on it (and I have more experience with the set) before I get into any physical modifications (lining the interior, lens hoods, etc.) as Chris White did…
http://www.bus.ucf.edu/cwhite/theater/ToshibaTips2.htm

Richard
Richard Casto is offline  
post #8 of 15 Old 10-21-2000, 12:44 PM
AVS Special Member
 
Guy Kuo's Avatar
 
Join Date: Feb 1999
Location: Seattle, WA
Posts: 3,172
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Richard, just found this thread. In answer to some of your questions...

The solar cell should track linearly enough to use the 30 and 100 IRE fields for calibration. I'd use full fields instead of window patterns to minimize the effect of on-screen lettering which may appear on your RPTV during adjustments. Those letters can bias the measurments, but using full fields helps reduce that contribution. Very reproducible positiong of the cell is critical. If position shifts betwen measurements, the numbers will be off.

The VHS cartridge optical comparator's slot is simply used to produce two different levels of lighting to compare with. If you use a typical type D fluorescent bulb, the bulb will be a tad too green. Lumichrome 6500 K bulbs are near ideal (slightly too blue), but are pretty difficult to find in single quantity. The last place I found them on the net sells them in lots of about 20.

I'd second having someone around to help before undertaking something like this. If you don't have any experience, it IS dangerous to your display and yourself. At the very least, it is nice to have someone who can perform CPR on you rather than leaving a body for your wife and child to find upon return home.

I'm rather surprised that this topic resurfaced. I quit thinking about it after it was clear that very few people would ever be really interested or motivated to do it.

------------------
Guy Kuo
www.ovationsw.com
Ovation Software, the Home of AVIA DVD



Guy Kuo
Guy Kuo is offline  
post #9 of 15 Old 10-21-2000, 04:52 PM
AVS Special Member
 
Tim Wilkins's Avatar
 
Join Date: Feb 1999
Location: central IL USA
Posts: 1,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Here is one site that sell D6500 bulbs and they also have a minimum order quantity too.
http://www.truesun.com/Lumichrome.htm
Tim Wilkins is offline  
post #10 of 15 Old 10-23-2000, 07:57 AM - Thread Starter
Member
 
Richard Casto's Avatar
 
Join Date: Sep 2000
Location: Raleigh, NC, USA
Posts: 101
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Guy,

Thanks for the help. Particularly the tip with the full field vs. windowed IRE pattern. I will make sure I place the cell the same way each time. Since my set it a 16:9 and the cells usually are quite rectangle, I will align them within the 16:9 raster area on each tube. I will have to make my own lens cap as I have a RPTV.

So, I think I have enough info to give it a try now. I WILL make sure I have someone with me before I open up the set.

My next step is to start purchasing the supplies for this project. It looks like a good 6500K high CRI tube will be the hardest. I checked out Tim’s link (which is for the Lumichrome 1CX 5000K/96CRI tube) and found the 1XX tube http://www.truesun.com/lumichrome1xx.htm on the same site. The 1XX is a 6500K/98 CRI tube (which I think you have mentioned in one of your previous post Guy). The info on the main lumicrome 1XX/1CX truesun.com pages make it look like you have to purchase them in a minimum of a 25 pack, but if you go to the order page, it looks like you can purchase them in a minimum quantity of between 2 and 4 (depending upon the size of the tube).

For example, the FW151XX (T8 18†15 Watt 790 Lumens), which I think I will buy, is listed at a minimum of 4 at $14.95 each. More than I want, but less than 10 or 25 at $14.95 each.

I plan on documenting the entire process and posting it (with photos) on my web site. Once done (At the least a few weeks), I will post a message on this forum to let you guys know how it worked out.

Richard
Richard Casto is offline  
post #11 of 15 Old 10-23-2000, 01:09 PM
AVS Special Member
 
Guy Kuo's Avatar
 
Join Date: Feb 1999
Location: Seattle, WA
Posts: 3,172
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
The last pet store 6500k high CRI bulb I picked up was definitely magenta tinted relative to the target color of white. The Lumichrome 1xx 6500 tubes are very good and I'd trust it over others.



------------------
Guy Kuo
www.ovationsw.com
Ovation Software, the Home of AVIA DVD



Guy Kuo
Guy Kuo is offline  
post #12 of 15 Old 10-23-2000, 03:52 PM
AVS Special Member
 
Tim Wilkins's Avatar
 
Join Date: Feb 1999
Location: central IL USA
Posts: 1,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Joel Silver was using a very small 6500K bulb in something he had when I was at CEDIA. I emailed someone else that also took the CRT Calibration class to see if he remembers the name of the bulb. Seems like the name began with the letter r and was used in biology labs, but it wasn't an aquarium bulb. I looked in my Grainger catalog and I didn't find anything that stood out. Usually the Grainger catalog has about everything made in it.
Tim Wilkins is offline  
post #13 of 15 Old 10-23-2000, 09:36 PM
AVS Club Gold
 
zarlor's Avatar
 
Join Date: Oct 2000
Location: Metairie, Louisiana, USA
Posts: 352
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
You can also get tubes rated 6500K with 90 or higher CRI from your local pet store. Aquarium florescents come in quite a few sizes and many different degree ratings. Easy enough to buy single bulbs this way usually in the $15 to $30 range. Just read the packaging carefully to be sure of what you're getting.


------------------
Lenny Zimmermann
zarlor@acm.org

Lenny Zimmermann
zarlor@acm.org
zarlor is offline  
post #14 of 15 Old 10-24-2000, 05:56 AM - Thread Starter
Member
 
Richard Casto's Avatar
 
Join Date: Sep 2000
Location: Raleigh, NC, USA
Posts: 101
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
What light source is used in the optical comparators that you get from the ISF? I am sure that they need to replace the bulb/tube for those from time to time.

Also, does anyone have a photo of an optical comparator that they can email me (richard.casto@peopleclick.com) or a link to a photo? Since I am building my own, it would be nice to see what a real one looks like.

Richard

[This message has been edited by Richard Casto (edited 10-24-2000).]
Richard Casto is offline  
post #15 of 15 Old 10-24-2000, 07:04 PM
AVS Special Member
 
Tim Wilkins's Avatar
 
Join Date: Feb 1999
Location: central IL USA
Posts: 1,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
The bulb used in the ISF optical comparater is the one I was talking about. I'm still not sure of the name of it.
Tim Wilkins is offline  
Closed Thread CRT Projectors

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off