Convergence repair in progress, 57H83 (long)

6401 Views 10 Replies 3 Participants Last post by lcaillo, May 12, 2012

Sprinty

Discussion Starter · Jan 30, 2012 (Edited)

Hi all, I have a 57H83 set with what I believe is a convergence problem, but I have been unable to resolve it over the past few weeks. I'll start with a description of how this all came to be, followed by the steps I have taken to try and resolve the issue. Thanks in advance for the help and support.

I'll try to give as much information as possible, so I apologize for the length

Background:

The tv resides in my basement/home theater and I don't get to use it that often, but recently wanted to recalibrate the set and get it back to it's best condition possible. In this process, I opened the set, cleaned the optics completely by removing the lenses. I also fixed a focus error on my blue lens and lined the cabinet with black felt. After I got the set back together, I began working on getting the set's settings adjusted and worked further on my service level convergence. After I got the convergence done I took it for a test run with a scene from Avatar and was completely blown away by the difference the cleaning made.

The trouble:

The set was running smoothly, when I heard a crack sound, which I thought came through my speakers, about a minute later the crack sound happened again, the screen went dark, then came back on and looked like someone kicked it right in the middle and the convergence was obliterated. I turned the set off and panicked, but then started to research the issue when I found various sites leading me towards a convergence repair. I'm a diy guy at heart but was worried that this might be out of my league.

It's clear to me that in some form or another, I caused some sort of short or malfunction in my jostling the set or in my process of cleaning, adjusting etc. but that's not really relevant

Repair steps:

I ordered a set of convergence ICs from a company that specializes in repair kits (this was prior to my thorough reading and finding the recommended supplier listing). I got the board out, replaced the ICs, looked for burned resistors and fuses (which I found none) and no such luck. Very disappointed, but I remain persistent in my efforts to want to get this fixed.

Since then, I removed the convergence ICs completely, to test the tv without them, then tried every combination of the old/new chips to see if maybe I had a failed chip from the new batch (I couldn't seem to find anywhere that said they failed in pairs, so I am assuming one may still be good but if you are replacing them, it certainly makes sense to replace both). Still no such luck in my repair.

I checked all the resistors, fuses and such that I could find related to the convergence board and looked over the board repeatedly for cracked solder points, etc.

I am pretty sure that I have missed something along the way but I am at a loss as to what that may be. I only removed the circuit board with the convergence ICs in it and not the power supply or signal boards. As such, I did not check for any blown fuses or resistors in either of those places.

Is it possible for a resistor to blow without any visual change? If so, how can I test that? What else am I missing? I don't mind ordering another set of ICs, but don't want to waste more money if I can't isolate the issue. I am toying with the idea of getting professional repair or upgrading the set, but would prefer to try and fix it myself

Here is a link to an image of what the picture looks like
http://imageshack.us/photo/my-images/259/20120119143404351.jpg/

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Twin_Rotor

· #2 · Jan 30, 2012

A quick search here will reveal several convergence threads that might help you out.

Most TV repair guys(the ones who visit this site) recommend replacing the resistors, if they're bad or not. A visual inspection of a resistor isn't a proper diagnostic proceedure. You really need to use an ohm meter to check the values(if you did use a meter, sorry. Your thread is unclear).

From my study of convergence issues, bad resistors will kill your new ICs. At least, thats my conclusion from my research. I've really never had a clear ansere on that issue.

Good luck!

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lcaillo

· #3 · Jan 31, 2012

An open resistor, or an open connection, can easily blow a chip. On the Toshibas, the problem often starts with bad connections, sometimes on the ICs sometimes elsewhere in the circuit. Moving the board around can crack connections as well. Resolder anything that has a ring on the solder joint, being very careful not to create any bridges.

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Sprinty

Discussion Starter · #4 · Apr 2, 2012

Update, after trying and retrying and testing, I finally broke down and called a pro to come help. It turns out that it was the puncushion circuit which was tracked down and replaced pretty quickly. While my repair was not successful, I have a completely new intimacy with my set and would have no problems replacing the convergence chips if they actually fail.

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lcaillo

· #5 · Apr 4, 2012

Never ran into a pin circuit failure on one of these, but it just goes to show that there are often a multitude of possible problems that can cause similar symptoms.

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Sprinty

Discussion Starter · #6 · Apr 4, 2012

Yes, I was going crazy checking solder points, fuses etc. Trying to find out the problem. Sadly, it seems as though a power surge may have killed my set after all of the drama. We had a bad surge a couple of nights ago, didn't think much of it as the set is plugged into a line conditioner. My htpc that I had connected to the set had some failure, which I assumed was from the surge, then shortly afterwards after turning the set off (was working fine) then back on, I've got no picture at all, just a black screen. Red light is on solid, but nothing on screen at all. Not sure if there is sound, since everything passes through my receiver but there's no response from changing inputs or anything.

I haven't gotten the chance to take a better look yet, so I am hoping this is a fuse issue or something similar, since I am not interested in spending a few hundred more dollars on another repair.

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lcaillo

· #7 · Apr 4, 2012

Do you have all incoming lines, like cable or sat, going through a surge suppressor and properly grounded? It is very common to find a cable line or other not well grounded...connected to your system even indirectly through a cable modem, you end up with a dangerous potential that results in current flowing through your system rather than to earth.

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Sprinty

Discussion Starter · #8 · Apr 4, 2012

I run all of my signal into my av receiver which is plugged into the surge suppressor with the tv. I have only one hdmi cable (dvi) into the back of the tv, no other signal wires. However, it came to me that the outlets may not be properly grounded. I recently swapped out all of the receptacles in my home to tamper resistant outlets because of babyproofing needs. I noticed the outlets in the basement tv room did not have a ground connected to the green screw.

Honestly I didn't even think anything of it other than there may be ground loop noise introduced. Then when my htpc wouldn't start up I immediately thought power surge and after thinking about it further, it came to me that the outlets may be the culprit. I bought an outlet tester so that I can verify the ground or lack therof. Either way, I've got some sleuthing to do inside of the set to see if I can salvage what is there. The set was functional for the morning prior to the screen going black, but I know that doesn't mean much.

Any ideas on specific points to check, other than the picture tube fuses? The set appears to be powering up. The red power light is solid and there is a pop from the speakers when turning on/off. The normal pop sound, nothing out of the ordinary there. However, since I have no sound bearing sources I can't tell if there is sound

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Sprinty

Discussion Starter · #9 · Apr 12, 2012

Well,

I took out my power supply board and was able to locate 2 burnt out pico fuses (which I never would have been able to do if not for my previous failed repair from my OP. Since I don't know of anywhere to buy the fuses locally, I had to wait an agonizing 4 days for them to try to see if that was the cause.

I replaced the fuses, soldered them back in, popped the board back into the light box, rewired it and boom, POWER RESTORED! I feel pretty accomplished and quite relieved. Hopefully no other drama comes my way soon.

Now on to repair my htpc that I lost in the same surge.

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Sprinty

Discussion Starter · #10 · May 12, 2012

Well, my luck was short lived. Unfortunately after I got everything back together I came across a couple of new issues.

1st. The geometry became skewed and distorted pretty badly, which makes sense after a complete loss of power that everything would be that way. The picture is skewed up about an inch or so, looks almost as if I were watching a letterbox movie, but with only a black bar at the bottom. There is a white horizaontal line about 2 inches long that is visible in the "letterbox" area. I believe this to be a signal to trip the light sensor for the auto-convergence.
After trying to adjust picture height and vertical location in the service menu, I was unable to do so because those settings were not responsive to remote button presses. Others were, such as convergence, rcut etc.

2. This is probably related to the last part of the above issue, but picture settings automatically reset to default when the tv is power cycled. It will remember input nu,ber and which setting is seleceted (I.e. standard, sports, movie, preference) but if I adjustcontrast down from 100 to 50 and power cycle the tv, it will reset back to 100 even after it has been saved. I'm not sure if there is a battery or anything that keeps power to some part of the board to remember this stuff. It's a similar behavior to when a pc has the motherboard battery fail and all of the settings reset with each power cycle.

3. This is least important but nonetheless. I use the set only with a home theater receiver with an hdmi-dvi cable so I have only the one input in use. However, when the set enters the tv or cable mode (antenna) where it would normally display snow shownow shows a distorted mess of colored bars running horizontally. If you remember back to the original days of nintendo when a game would fail, it looks like that

I don't really care so much about fixing the snow on the antenna input and truthfully this is becoming more of a hobby project than anything else, I would like to get the set fixed, by myself. My time is limited so it takes days or even weeks before I can spend a few hours working on it.

I know that it is "close" to working so I haven't given up, but I'm not really sure what else could have failed that would cause the new behaviors.

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lcaillo

· #11 · May 12, 2012

It sounds like you have a vertical deflection problem. Not uncommon. Look for a bad cap in the vertical output stage.

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