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Crumbtrail TV Forums: TV Equipment: Projection TV Forum:
hitachi 50fx18b horiz compress

 

 


m103368
New User

Feb 6, 2010, 11:36 PM

Post #1 of 14 (1780 views)
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hitachi 50fx18b horiz compress Can't Post

when it works it works great, but randomly the picture gets reduced to about 8in horizontally in the middle of the screen, any help would be greatly appreciated.



Ron.M
Veteran


Feb 7, 2010, 2:29 AM

Post #2 of 14 (1772 views)
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Re: [m103368] hitachi 50fx18b horiz compress [In reply to] Can't Post

m103368;....

I may be able to help you....
As this is NOT an adjustment or anything you can do from outside the set ,
you will have to go inside ...So....
I need to know your background in electronics/TV repair experience...
You may have an intermittent bad solder connection....Unsure....

Also , I need to be sure we are on the same page here....
When you said;=>""the picture gets reduced to about 8in horizontally in the middle of the screen,"" , do you mean the pix shrinks to 8in accross the screen from left to right OR top to bottom ????

Thanks....Laugh...

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


m103368
New User

Feb 7, 2010, 1:13 PM

Post #3 of 14 (1768 views)
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Re: [Ron.M] hitachi 50fx18b horiz compress [In reply to] Can't Post

The picture is displayed from left to right (horizontally) across the whole screen, about 8in tall. I am not a TV technician, but know a little about electronics, i guess enough to be dangerous. if something needed to re-soldered, or replaced, i think i could do that. I poked around inside, re-seating boards and connectors, wiggling components, but of course i have no idea on where i should be looking. thanks again for any advise you could shed.


Ron.M
Veteran


Feb 7, 2010, 7:49 PM

Post #4 of 14 (1753 views)
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Re: [m103368] hitachi 50fx18b horiz compress [In reply to] Can't Post

m103368;.....

You have a problem better known as "partial vertical collapse"

OK...A few questions....
Does the pix collapse after the set is on for awhile ???
Or does it do it at random with no set time ???

When you went poking around inside did you happen to notice if anything was happening to the vertical size ???...Any changes ???


This is where you should be looking (See pix below) BUT do NOT go there yet....
I will give you detailed info as to what to do later , after you answer all my questions...Thanks....





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


m103368
New User

Feb 7, 2010, 10:18 PM

Post #5 of 14 (1750 views)
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Re: [Ron.M] hitachi 50fx18b horiz compress [In reply to] Can't Post

Does the pix collapse after the set is on for awhile ???
Or does it do it at random with no set time ???
I thought it was random, but last night it collapsed and would not come back The set was on for a few hours working perfectly before it went bad. Actually it happened during the few hour working perfectly (guess not quite so perfect), i shut it off, and back on, and it went back to normal. Then, hours later, it went south and did not come back. i haven't tried today (i switched sets).

When you went poking around inside did you happen to notice if anything was happening to the vertical size ???...Any changes ??? My "observer" in front of the set did not notice ANY changes.


Ron.M
Veteran


Feb 8, 2010, 12:28 AM

Post #6 of 14 (1744 views)
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Re: [m103368] hitachi 50fx18b horiz compress [In reply to] Can't Post

m103368;....

OK , good info...Thanks...


BTW:=>..Before we get too deep for you;..IF you have any problem with the way I'm explaining things , my requests for you to do certain things to find this problem , or anything slse , PLEASE STOP doing it & POST here & I'll try to figure out another way to hopefully get the desired results....OK ????

Reffering to the pix below....
That board is on the right hand side as you face the rear of the TV...
I601 is the vertical output IC...
It is in the center towards the front of the board....
It is on an aluminum "heat sink" that becomes quite warm (Maybe hot , in your case) after an hour or so....
If you were to look at the face of the IC , you will see LA 7838 which is it's name...(type)...
What I'm asking you to do is;...
1st;.Have the back open so you can get into it easily when the time comes....
Turn the set on & watch it til the pix collapses....
Then go to the vertical IC "heat sink" (carelul , it may be hot) & gently move it slightly in all 4 directions while your "observer" watches for any changes in the pix size...Post results...
Do NOT force it...
2nd;. Using the insulated handle of a small or medium sized screwdriver , lightly tap downward the top ONLY of the "heat sink"....Post results...
3rd;. IF you see ANY changes while doing either of the above 2 steps , STOP IMMEDIATLY... If you continue to aggravate the problem , you can cause further damage....


Your problem IS on that board , known as "Power/Deflection P.C.B. (Printed Circuit Board)....
Very likely the IC is causing the problem....
You may have to replace it...
OR you have bad P.C.B. connections....
Either way , you will need to get at the bottomside of that board....
My question is;...How do you feel about removing that board to do what needs to be done ???
There are several connectors etc , that have to be disconnected & screws to take out , to do this job....
Are you going to be comfortable doing this ???
IF not , let me know....OK....
Also , can & are you able to take & post pix in case they're needed ???

THANK you....Laugh.....

Have fun & GOOD LUCK....






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


m103368
New User

Feb 8, 2010, 12:51 AM

Post #7 of 14 (1740 views)
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Re: [Ron.M] hitachi 50fx18b horiz compress [In reply to] Can't Post

OK Thanks for the info! Can't get to it right away, i'll get to it as soon as i can, probably after work tomorrow. No problem taking stuff apart, if there is a board that has to be removed, i'm pretty sure i can get it out. thanks again...


m103368
New User

Feb 9, 2010, 1:20 AM

Post #8 of 14 (1732 views)
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Re: [m103368] hitachi 50fx18b horiz compress [In reply to] Can't Post

OK, moving the heat sink front and back, left right, did nothing, taping down on the heat sink did cause the picture to momentarily go to full screen.


Ron.M
Veteran


Feb 10, 2010, 12:31 AM

Post #9 of 14 (1719 views)
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Re: [m103368] hitachi 50fx18b horiz compress [In reply to] Can't Post

m103368;....

OK , that sounds like good news....

I hope you followed this advice;=>..

Quote
IF you see ANY changes while doing either of the above 2 steps , STOP IMMEDIATLY... If you continue to aggravate the problem , you can cause further damage....

IF you did , we/you're in luck.....
What you have is a bad PC connection/s at or near the Vertical output IC....(LA7838)
Leave the TV off & UNPLUGGED overnight BEFORE you start....
That allows for safe discharge of unsafe voltages...
You need to remove the board in such a way that you can flip it over upside down to see & get at the connections....
You should be able to do that without disconnecting the 4 heavy red wires coming off the Flyback...
In the pix below , the heavy lines represent wiring you need to disconnect....
Except the flyback...That will hold a charge that will put you on the Space Station or beyond....
Do not forget the smaller jumper type connectors (6 of 'em) going from this board to the one on the left side...
Do NOT force these as they can be easily broken...If you need help with these , please post...
Unscrew , if any , screws that hold the board down...
There may be some plastic clip/clamps holding the board down....
The large "heat sink" on the right side (For the convergence ICs) may have screws holding it in place...
Also check around the flyback for screws holding it in place.....
Once the board is free , try to set it upside down so the vertical IC is towards the rear of the set for easy access to the connections....
Use care doing this as the weight of the flyback & the heat sink with the ICs make for a flimsy manuever to do...The PC board is quite flexible & can be easily cracked ...USE CARE !!!
After you re-solder the Vertical output IC connections , PLEASE do the flyback connections also...Just precautionary....

The 2 links below are for soldering lessons which may or may not be of interest to you....

One paragraph is important...This one;=>...


Quote
A good connection is one where the solder has uniformly flowed over all the surfaces to be connected, following their contours. The connection appears bright, shiny, and smooth, with all wires in it appearing well soldered. However, if the connection is rough, grainy, or flaky looking, or if the solder formed into little round blobs, or has ridges or sharp points, redo it. Take the time to visually check the connection with those points in mind.
If the joint is a "cold" connection, caused either by insufficient heat, a wire moving, or foreign matter (such as oxides) getting into the connection, the cure is simple and direct: re-heat the joint and apply a little more solder. If that would place too much solder in the joint, you will have to remove the solder before trying again.


If you do have enough experience , skim thru the 2nd link....
One thing about soldering;..Do not leave the soldering iron tip on the connection for too long as the heat can lift the foil off the board & possibly damage it....

When you solder the vertical IC , notice that the pins (13 of those) are very close together....
Use care not to have any solder bridges between any of the pins or you WILL blow something when you turn on the TV...
Use a magnifying lens or glasses & check for bad connections around the Vertical IC & repair those that look suspicious or are bad....

Reinstall the board & all connectors....
Send email to your religous leader (IF you have one) & ask for all their help.....Wink....
Turn on the TV....
Watch the board first (NOT the screen) for any smoke or overheating parts in the area you worked in....
If nothing seen , check the pix....
Post back with results....




http://www.pc-control.co.uk/soldering.htm


http://www.elecraft.com/...SS_SolderNotesV6.pdf



HAVE FUN & GOOD LUCK.....Sly....






Also , PLEASE answer this;=>...
""Can & are you able to take & post pix in case they're needed ???""
Just in case...Angelic...
Thanks...


IF you have problems getting the board out , turning it over , etc , STOP & post...
OR any other problems....
I will answer asap....


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


m103368
New User

Feb 10, 2010, 12:51 AM

Post #10 of 14 (1716 views)
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Re: [Ron.M] hitachi 50fx18b horiz compress [In reply to] Can't Post

cool, we'll give it a try, if all goes well, you can tell me where to send the check..., really appreciate the help!


Ron.M
Veteran


Feb 10, 2010, 8:43 PM

Post #11 of 14 (1711 views)
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Re: [m103368] hitachi 50fx18b horiz compress [In reply to] Can't Post

m103368;...



Quote
if all goes well, you can tell me where to send the check...,


FYI;....I , & as far as I know , NO ONE here accepts ANY gratutity of ANY kind for what we do...
We are all volunteers who do this for gratus....
Thanks anyway , but with all due respect , NO thanks...Sly....


Whether or not all goes well (& I certainly do hope ALL goes well) PLEASE post back with results.....THANK you....

In the event I don't hear back from you, You're welcome....Sly....


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


jts1957
Veteran


Feb 11, 2010, 12:45 AM

Post #12 of 14 (1709 views)
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Re: [Ron.M] hitachi 50fx18b horiz compress [In reply to] Can't Post

Speak for yourself!Tongue

Send WINNING lottery tickets, CASH or uncancelled stamps to....PM me for details.Cool


-------------------------
Location: Far, Far Away


m103368
New User

Feb 12, 2010, 1:15 AM

Post #13 of 14 (1696 views)
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Re: [jts1957] hitachi 50fx18b horiz compress [In reply to] Can't Post

Ron.M, Eureka! Found a bad solder on one of the pins on the IC you pointed out, re-soldered, re-installed board, no problem. set has been running without any problems for a couple days. Thanks!!!! Sould have put a ha, ha after the check comment, just joking. Really Really appreciate your help and time researching this problem, you're obviously a good guy, the world needs more of guys (and gals) like you.


Ron.M
Veteran


Feb 12, 2010, 2:13 AM

Post #14 of 14 (1693 views)
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Re: [m103368] hitachi 50fx18b horiz compress [In reply to] Can't Post

m103368;.....

Glad to hear the good news.... Sly...Smile....


Quote
Found a bad solder on one of the pins on the IC you pointed out, re-soldered,

I hope you did ALL the pins on that IC ....



Quote
set has been running without any problems for a couple days.

If you would like to prove it do this again;=>...

Quote
2nd;. Using the insulated handle of a small or medium sized screwdriver , lightly tap downward the top ONLY of the "heat sink"....

If there's no flicker or any change in the vertical , you got it whipped....



& You are most welcome......
Enjoy the set.....



Later....Ron.M....Cool....



Veteran & Retired TV technician

(This post was edited by Ron.M on Feb 12, 2010, 2:23 AM)

 
 
 


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