Question about Akai PTH5498 54" Rear Projection HDTV-Ready Television
Tv used to have a great picture. Now it's a little blurry and the colors are never right. When I try and do a convergance NO SENSOR DATA shows up for blue. The red seems to work ok. Last summer had lighting strike the house and got several eletrical appliances. Thjis didn't show up before the lighting strike but sometime after.
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Posted on Jan 02, 2017
you will have to go in the service mode. be careful as you could damage the tv if wrong settings are changed. with the tv off push on the remote display 5 vol+ power. now hit the 1 button until you see pje fdis on the upper left. now push the 9 button to enter convergence. you should now have a cursor on the screen. usr the 3 button to switch colors. use the directional pad on remote to move the cursor and the enter button in the center of dir pad to select or deselct a point in the screen. push muting and then enter to save convergence. now restart the tv and all done
Posted on Oct 13, 2007
SOURCE: Akai PT4298HD Rear Projection
Perfect Focus and the convergence screen are for convergence, not actual focus. Real focusing is done in a combination of two ways: electrostatic and optical. And to do it right you need a good test pattern, like the convergence pattern from the Digital Video Essentials DVD. At a bare minimum turn your contrast down to half (don't use "dynamic" mode, ever).
This is going to sound scary, cuz it terrified me at first but now I'm comfortable with it:
To focus electrostatically, the front panel under the speakers needs to come off. As in actually unscrewing some screws and opening up your tv. Do all of this without cats or toddlers in the room. There are three circuit boards on which the picture tubes are mounted, and each board has a focusing knob next to the words "red," "green," and "blue." Do not touch ANYTHING other than these knobs. Twist the focus back and forth until it is as focused as it will get. The lines on the convergence pattern will get fatter or skinnier. If they get fat in one direction and skinny in the other, find the best compromise. Do not focus the blue too perfectly, as perfectly focused blue lessens the amount of blue relative to the other colors, making whites look yellowish.
Next you really need to clean your lenses, they are filthy from dust and that's why the focusing is so bad. For this tv, you'll want all three panels on the front to come off. That's about twenty screws, both on the sides of the tv and the undersides of the panels. The middle panel that covers the speakers can rest on the floor by the front panel, but the screen panel needs a resting place. An ottoman, or a chair with a towel on it, makes a good place to rest the screen (parallel to the floor).
Each CRT has a set of focusing lenses, and these can be removed. Do one at a time. They come off from four screws each. FOUR SCREWS. Do NOT unscrew anything else, as just under the lenses is a cover for the CRT. Take this off and you risk coolant leak, leading to expensive electrical problems. Do not, repeat, NOT touch either the lenses or the mirror with your fingers. One scratch is bad. Scuff marks can destroy a picture. These lenses and mirror are easily damaged.
There are some cleaning techniques there. I'd only bother cleaning the top and bottom of the lens assembly. Don't mess with the wingnut on the side, we'll handle that later.
Now, with your CRT lenses back on (wingnut facing towards the mirror), replace all of the panels and rescrew the screws. Next we do optical focusing. Again, this is where test patterns from a test pattern DVD come in handy. Regardless of what TV a person owns, a DVD like Digital Video Essentials is, well, essential.
This time we're taking a panel off the *back* of the TV. Scary, huh? Specifically, the bottom one (there are two big back panels). About fifteen screws, four of which are the same ones you do to get the front bottom panel off. Get all of the screws off, pull it back, and lift it out. Don't touch any of the electrical stuff. From here, if you are careful, you can reach up under the mirror and untighten the wingnuts on each CRT lens assembly. If you are using a test pattern, use a standard definition one here, makes the scanlines easier to see.
Here's what I do to focus each gun:
1) Put on a full screen of green, red, or blue, depending on which gun I'm focusing. DVE has just these patterns.
2) Untighten the wingnut, and start making minute adjustments.
3) What you want to see is *scanlines*, as clearly as possible. Make a tiny adjustment, get back around to the front of the tv, and see how well you can make out scanlines. An all-green screen should actually be a bunch of horizontal lines of green. If you can't make out these lines, you aren't focused.
4) If you don't seem to be making progress at all, switch to DVE's convergence pattern to make sure you haven't completely lost focus on that color. You want to start from good focus, and then fine tune very delicately.
5) You may find it hard to get blue-focus perfect. That's okay, really, as blue is a filler color. Green was very hard for me to see lines on, but it was a step up from not being able to see them at all.
6) You may find it necessary to go back and forth between electrostatic focusing and optical focusing adjustments to get them right. That's okay.
7) When it seems you've done the best you can, you're done. Put the back panel back on and rescrew all of the screws.
Now you need to adjust your convergence. You can use the user convergence menu, but it will only get you halfway there, because it only controls like nine or twelve points. What you want is to access the *service* convergence menu. With the tv on, press mute-1-8-3 on your remote (not pressing them all down, just in that sequence). You should switch to a secret built-in convergence screen.
I hate to tell you this, but the only way to save settings made in the service convergence screen that I know of is with a Samsung remote, not the Akai one. This tv is actually a Samsung after all, and the Akai remote is missing some buttons that the Samsung remote has. You can buy them off partstore.com, among other places. Here are what the buttons do:
7-allows you to control red convergence
8-allows you to control green convergence (what the screen defaults to)
9-allows you to control blue convergence
+100-turns red on or off
0-turns green on or off
pre-ch-turns blue on or off
circular direction buttons-moves the cursor to a new convergence point
channel up/down-moves the convergence up or down
volume up/down-moves the convergence left or right
ONLY ON THE SAMSUNG REMOTE:
add/erase-saves settings after blinking the screen and centering the cursor
If you can find a button on the Akai remote that does that, you won't need to buy a Samsung remote.
BTW, you'll want to do this service convergence on each scan rate. So one for 480p (from a progressive scan DVD player), once for 480i (s-video source or non-progressive DVD player), and once for HD (I use my HD DVD copy of DVE).
Posted on Mar 19, 2008
The tv has 2 focus adjustments for each tube, mechanical and electrical.
1. Mechanical focus is set by looking at screen from back (through inspection plate on back of most samsungs) and rotating the lens assembly on CRT. loosen wing nut and turn lens assembly to go through focus and back to best position.
Put convergence pattern on screen and manually misadjust bottom red and green lines convergence so they can be seen through inspection hole.
With back cover of TV off you can usually reach your hand up beside the lens assembly to loosen the wing nut then rotate to adjust. Green is in the middle. The focus will be obvious when you rotate and look
When you are finished make sure the foam dust protector is not over any of the lens assemblies and the wing nut is tight.
2. Electrical focus - located at front of unit. the front grille/speaker cover is removed and maybe a cover over the front crt inspection hole.
In the inspection hole there is a black plastic "Focus/screen adjust Assembly" with 2 rows of 3 controls.
One row is focus and the other is screen. The middle controls are for green with R/B on either side. Usually the controls are labelled as "focus" and "screen". You want to adjust the focus controls, one for each color. Look for the focus or screen label imprinted in the plastic. Don't play with the screen settings.
With the same misadjusted convergence pattern you can see a red, blue and green line. Adjust green focus and watch green line for best focus. Do same for other 2.
Screen adjustments are very exact and delicate. The easiest way to deal with them is to turn color off in Customer adjust menu. Put any color tone adjustments in the middle (low, med, high, put at med).
You should have a b/w picture if there are no crt or other color related faults. If it is close to B/W leave screens alone.
If the pix is too green, then the green screen setting must be reduced a small amount. Do not play with these adjustments as most TV repairrers have a difficult time adjusting them.
If focus adjustments don't help then focus control or CRT may be defective. Needs expert to determine.
Posted on Jun 25, 2008
SOURCE: Convergence comes and goes.
OK, THIS model uses two STK-392-110 convergence IC's--if hitting the set makes the convergence come back you may have bad solder connnections on them====each has 18 pins--considering the labor just to get at them to solder them---i would replace both anyway, even if I find bad connections on them---one of the reasons they fail is the back of each is metal and a white grease to transfer heat to the metal they are attached to dries out---this set is old enough the grease is now probably dry--YOU CAN BUY BOTH IC'S FOR LESS THEN 13 DOLLARS ON EBAY PLUS SHIPPING----Not a do it yourself job if you do not have certain skills---shop around in your area---here I do this in home for people for 200-250 depending on the set----shops get 3-4 hundred and some do not do it in the home---I don't have to tell you the economy is poor right now; and this time of year is the slow time for most tv repair shops---find someone who has done this kind of repair on your brand of set--a good tech can do it in about an hour right in your home---200-250 is a good price--you cannot replace the set for this kind of money.
these sets are much more dependable then LCD or Plasma TV sets--not one of those sets get fixed in the home--and 80% of them that come into the shop I work for are less than 2 years old--if you buy one get a 3 year warranty.
If this has been helpful give me a vote here--I do this for free--you need help or have any questions:
Posted on Aug 24, 2009
Testimonial: "etower, thank you very much. Extremely knowledgeable, precise, explained it very well. Thank you so much. "
I know this set very well---you are saying convergence adjusts ok everywhere? If you understand that the blue is usually de-focused a little----there are only two ways to adjust the focus of each tube-----
1.) Behind the front speaker grill there is an inspection plate---with it removed you will see a small black plastic block with 6 controls on it; it is the MASTER SCREEN/ FOCUS BLOCK
2.) THREE of the controls left to right are Screen controls(red, green and blue) and the other 3 are FOCUS--IT IS ALL black and you need to look close to identify which is focus and which is screen---you are looking for the BLUE focus control(one of the 6)
3.) With the convergence grid on screen cover the RED and GREEN lens in the set and try to adjust the focus of the blue(I presume you know how to put the set into the Convergence mode?
4.) The only other way to adjust the Blue focus is from the back of the set---with the Red and Green lens covered up place a blanket over the top of the set that covers the whole screen--from the back of the set you will note that all three of the black focal lens have a wing nut---with the convergence grid up and only blue lines present(Green and Red lens covered with a cloth) look from behind the set at the grid---loosen the wing nut on the blue lens and slowly slide the lens left or right until the blue has the best focus possible----if it will not adjust with the focal lens or the front focus control you have a circuit problem.
I do this here for free and if this information helps you take a minute and give me a vote here. If you have any questions or need advice reply to this posting here and I will assist you.
Posted on Sep 15, 2009
Testimonial: "Thank You! Much better quality now! Your advice was dead on. I did not think it was convergence problem....One more Q, where do I send the beer?"
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