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Crumbtrail TV Forums: TV Equipment: Projection TV Forum:
Toshiba 57H94 Blue Alignment Problem

 

 


hugh.evans
New User

May 15, 2011, 7:26 PM

Post #1 of 11 (4982 views)
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Toshiba 57H94 Blue Alignment Problem Can't Post

I've had my Toshiba 57H94 in storage for the past year, upon firing it up again yesterday I found that Red and Green converge normally. During auto convergence parallel lines go across the screen normally for all colors but blue, which displays straight lines that are wider towards the left and narrower towards the right of the screen (almost forming a triangle.) Manual convergence allowed good adjustment of Red and Green, Blue was fully responsive both horizontally and vertically but way out of alignment so that it could not be may to fully converge.

Based on these symptoms it seems more like the blue CRT is out of alignment. Either that or perhaps one or more resistors has drifted out of spec. I initially suspected convergence ICs, but if I am able to move the cross-hairs in all directions it seems to suggest another problem.

Any thoughts or suggestions will be appreciated. If anyone has a link to the technical service manual for this set or would be willing to send a copy, tell me where to get one, etc. it would be a huge help. I am experienced with soldering, electronics repair, and working with high voltage equipment. If pictures would be helpful, I can try to take a few.

Thanks!!!



Ron.M
Veteran


May 15, 2011, 8:14 PM

Post #2 of 11 (4975 views)
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Re: [hugh.evans] Toshiba 57H94 Blue Alignment Problem [In reply to] Can't Post

hugh.evans;....

A pix showing ""the blue which displays straight lines that are wider towards the left and narrower towards the right of the screen (almost forming a >> triangle << .)""
would help a lot....

Also a pix of the convergence setup showing the crosses of blue out of whack & a full screen shot of the above...


THANKS....Sly...




Quote
I initially suspected convergence ICs, but if I am able to move the cross-hairs in all directions it seems to suggest another problem.

Maybe , maybe not....Depends on how bad it is...


Service manuals;=>....
http://elektrotanya.com/...94.pdf/download.html
OR;=>..
http://elektrotanya.com/...v2.pdf/download.html
That one is a revised(?) manual...
Scroll down about halfway & click on the "Get Manual" in red letters...


PS;...
When you post the pix , use "Preview Post" to be sure that we do NOT need IMAX to view them...Wink...



Later...Ron.M....Cool....
Veteran & Retired TV technician


hugh.evans
New User

May 16, 2011, 1:51 AM

Post #3 of 11 (4967 views)
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Re: [Ron.M] Toshiba 57H94 Blue Alignment Problem [In reply to] Can't Post

Ron-- Thanks for the quick response and links to the technical manuals.

Here is a picture of red during touch focus, for reference:



Blue, on the other hand, looks like this:



and this:



Here is a shot of the convergence screen. The highlighted cross has been adjusted as close as it will go to proper alignment. Looks like red needs a bit of tweaking as well.



Let me know if any additional pictures or details are needed or would be helpful. By day I'm a technical specialist in the adhesives industry, so I fully appreciate how much information helps when solving a problem.

Thanks again!


Ron.M
Veteran


May 16, 2011, 7:35 PM

Post #4 of 11 (4947 views)
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Re: [hugh.evans] Toshiba 57H94 Blue Alignment Problem [In reply to] Can't Post

hugh.evans;.....

I'm NOT convinced you have a convergence IC problem...Yet....

Here's what we/you need to do....
Remove the back cover...
Inside the set on or near the main chassis look for 2 large aluminum finned heatsinks....
Each one will have a large black IC with 18 pins held on by 2 screws...
Those are your convergence ICs......
On each one will be marked STK394-250A...
At one end of that board will be 3 connectors...
They are P710 , P711 & P712...
They go to the blue , green & red respectively....
ALL those connectors are the same...
Disconnect & switch the red (P712) with the blue (P710) wires that go to the yokes....
Leave the center (green) alone & where it is...
See page 41 in the "ET" manual &/or page 45 in the Rev2 manual for further info....
Then turn the set on & re-take the pix you posted before...
Disregard the way the pix looks...
It WILL be different...
I need to see the blue & red as it is now...
In essence , I want you to repeat the 3 pix you took earlier....

Now...
Let me make this PERFECTLY CLEAR !!!!
You have (Maybe) 2 service manuals...
Do NOT UNDER ANY CIRCUMSTANCES go into the "Factory Menu" also known as the "Service Mode"...
Unless you KNOW what to do & what you ARE doing , you can PERMANENTLY mess up the TV BEYOND repair....

I discovered that those 2 manuals you may have do NOT have any schematics...
IF you understand electronic schematics , I'll be happy to give you a link for that manual...

PLEASE post 3 pix...
(Include "Touch Focus")

THANKS....Sly....


Later....Ron.M....Cool....
Veteran & Retired TV technician


hugh.evans
New User

May 18, 2011, 5:11 PM

Post #5 of 11 (4930 views)
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Re: [Ron.M] Toshiba 57H94 Blue Alignment Problem [In reply to] Can't Post

Sorry for the delay, I should have a chance to swap the connectors and take a few pictures this evening. While doing a bit more reading on the topic, it appears the better description for my problem is keystoning. I assume this test will prove that this is the case if blue remains similar, but if red takes on the same pattern it will establish a convergence problem? What is the likely remedy if convergence ICs are ruled out? Just curious to know.
Thanks!


Ron.M
Veteran


May 18, 2011, 5:30 PM

Post #6 of 11 (4928 views)
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Re: [hugh.evans] Toshiba 57H94 Blue Alignment Problem [In reply to] Can't Post

hugh.evans;.....

Yes , you are correct,that is called "keystoning"....
IF after you switch the connectors the red changes to what the blue did previously , then the convergence circuit is at fault...
Most likeky , the ICs...

Post results & pix when you are ready....
THANKS....Sly....



Later...Ron.M....Cool....
Veteran & Retired TV technician


hugh.evans
New User

May 19, 2011, 3:53 AM

Post #7 of 11 (4918 views)
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Re: [Ron.M] Toshiba 57H94 Blue Alignment Problem [In reply to] Can't Post

I was unable to run convergence as before, but it appears the adjustment I applied to blue transferred to red and that blue is still keystoning. Here you go:




Ron.M
Veteran


May 19, 2011, 4:41 PM

Post #8 of 11 (4909 views)
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Re: [hugh.evans] Toshiba 57H94 Blue Alignment Problem [In reply to] Can't Post

hugh.evans;....


That came out a bit inconcluseive....Sorry about that....
Need to confirm my suspicions...
Last test...
Return the yokes to their original connections...
Then switch the blue (P710) with the green (P711) & try the same thing again...
See if you can get the "touch focus" to run...
PLEASE post the same 3 pix as earlier....THANKS....Sly.....



Quote
I was unable to run convergence as before,

Any reason as to "why" ????

Have a GOOD day.....Sly....



Later...Ron.M.....Cool....
Veteran & Retired TV technician


hugh.evans
New User

May 19, 2011, 6:01 PM

Post #9 of 11 (4904 views)
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Re: [Ron.M] Toshiba 57H94 Blue Alignment Problem [In reply to] Can't Post

Okay, I'll give that a shot. I'm unsure of the reason, but the menu system did not respond normally to arrow buttons (brought up some other menu) that I needed to access touch focus for the other pictures... Very odd given that I tried it 4 or 5 times and I can't imagine those lines are handling anything other than signals.
What I can say I saw is that blue was unchanged and that the convergence pattern applied to blue seemed to carry over to red. But, I see exactly where you're going with this so I'll get those pictures to confirm your suspicion.
Thanks again for your time and knowledge!


Ron.M
Veteran


May 19, 2011, 6:51 PM

Post #10 of 11 (4900 views)
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Re: [hugh.evans] Toshiba 57H94 Blue Alignment Problem [In reply to] Can't Post

hugh.evans;....


THANK YOU !!!!
Just to clarify...
I would like to see what the blue looks like on the green yoke & what the green looks like on the blue yoke....
The results should clinch it...



Thanks again....Sly....


Later...Ron.M....Cool...
Veteran & Retired TV technician


Ron.M
Veteran


May 23, 2011, 7:27 PM

Post #11 of 11 (4883 views)
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Re: [Ron.M] Toshiba 57H94 Blue Alignment Problem [In reply to] Can't Post

hugh.evans;.....

You have a nice weekend ????...Sly....

Having a problem with the pix ???....Unsure....

See ya soon , I hope....Wink....



Later...Ron.M.....Cool...
Veteran & Retired TV technician

 
 
 


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