CRT based RPTV Convergence Repairs

**difner** · **07-19-08, 05:51 PM**

I have a question on my Pioneer elite pro 118 RPTV

From looking at the forums and other info I believe that my convergence chip is most likey bad
the question i have is i can onlt find one stk chip in the front panel of the tv the chip number is stk4274 is that the convergence chip for this tv and is it the only one.

Here is a link to what the picture looks like http://sheltonfamilyonline.net/tv.jpg
Thanks
Alan

**lcaillo** · **07-19-08, 09:51 PM**

This set uses the STK4277L for convergence, which is a 5 channel IC. It uses a single STK4274 which, IIRC, drives the vertical deflection. The convergence IC is under the heat sink.

Be careful to buy the part from one of the distributors in the parts distributor thread, and look for bad solder joints and damaged resistors.

**difner** · **07-20-08, 08:14 AM**

Thanks I found the other IC its a big one. All the solder joints look good around the chip but i did find a capacitor I think that had a bad solder joint and i fixed it so hopefully its just a bad chip and not a whole board. Also should I replace both ICs or just the STK4277L one. Do you know if I could buy a whole convergence board or would it cost to much thanks again for the help.
Also Is there a place i can get a service manual online for this tv

Alan

**lcaillo** · **07-20-08, 02:37 PM**

I do not replace boards. I doubt that the board is even still available, and might be several hundred dollars if it is. I would change the parts that are bad and any that are suspect. I doubt that the small chip is a problem but I am not there with a scope to test the set.

There are links to places to find service manuals in the useful links thread:
http://www.hometheatershack.com/foru...ful-links.html

**07-22-08, 03:22 PM**

I have a Panasonic PT-65WX50 65" Widescreen RPTV 01-05-2001
The symptoms look and sound the same for requiring replacement of the convergence chips.

The slight difference is that I had the TV recalibrated 5 months ago. The TV was starting to look darker and it had lost some of it focus and clarity over 7 years. I happen to own the service manual.

The first technician sharpened up the picture and convergence, but messed up the pincushion in the process, and refused to come back and fix it.

The second technician managed to make everything perfect. This was not a simple convergence. In both cases various resolution grids were on screen and each point adjusted for RGB.
I also printed alignment grids for the task.

So now I am wondering if I was seeing early signs of chip failure 5 months ago.
I am also wondering if the adjustments we made back then are going to create a need for another lengthy recalibration to adjust for the new chips.
It's that concern that has me calling for the professional, rather than firing up the iron.

**lcaillo** · **07-22-08, 04:03 PM**

Generally, when replacing output ICs, you end up needing to do minor convergence adjustment. Major geometry would be rare. If, however, the set was ajdusted with a failing component, it may be that more correction is needed once the parts are replaced. There is no way to tell other than to repair the set and observe.

**07-27-08, 09:30 AM**

What a wonderful thread!

I have a Magnavox 51MP392H/17, and the red convergence has died. I checked inside, there are a couple of resistors that are discolored, (along with associated discoloration on the PCB. I was unable to find out if the STK394-160 IC's are drop in replacements for my model, so I ordered the 394-120's, and a bag of resistors, (from one of the recommended suppliers). Now to find a service manual....

**difner** · **07-27-08, 02:02 PM**

I installed the new IC on Friday I didnt have any of the thermal grease to put between the chip and heatsink i will get that today but i did hook it all back up and turned the tv on for a few minutes just to test it and it did fix the problem but it was not on for long. after i get the grease for the heatsink i will test it more by watching tv again

**08-12-08, 06:15 PM**

Quote:

DngrMse wrote:

What a wonderful thread!

I have a Magnavox 51MP392H/17, and the red convergence has died. I checked inside, there are a couple of resistors that are discolored, (along with associated discoloration on the PCB. I was unable to find out if the STK394-160 IC's are drop in replacements for my model, so I ordered the 394-120's, and a bag of resistors, (from one of the recommended suppliers). Now to find a service manual....

I found the service manual online, (very inexpensive). While taking things apart, and removing the dead ic's I discovered that one of them had a single 'glob' of heat sink compound...that covered approx 20% of the metal back....and that was the only contact the ic had with the heatsink. It was very thick....and dried out. Replaced both IC's, (I used arctic silver thermal compound), and four 6.8 ohm resistors. Fired it up, worked great, and convergence was dead on.

Question for anyone with a similar set: How long do the crt's last? I read somewhere that 10,000 hours was about all you could expect, and another site simply said years and years. I'm trying to decide if it might be worth looking for some spares, while I don't need them...in anticipation of when I will.

**08-13-08, 03:31 PM**

I am new to this Forum and am also a novice in the TV/Electronics area.

I have a Sony KP-65WV700 Rear Projection 65" TV that started to show Convergence problems.
I had a technician take a look at the set and he basically said that it is going to cost at least $550 to replace the IC chips.
He also said that the problem looks like it is probably more than the IC chips, but he cannot confirm until he fixes them first.
He suspects the DCU (Digital Convergent Unit) may also have gone bad because he sees a lot of distortion on the top and bottom of the screen.
That would cost me another $500, if it happens to be the case.
All in all, it is going to be at least $550 and at worst $1100.

There is no reason to suspect him because he also said that it is in my best interest to start looking for a new TV instead of spending on repairs.

Having said all that, I thought that I should probably try to repair it myself (after reading this forum) before I throw the TV out.
I have got nothing to lose - correct?

I understand most of the things said here in this forum, but would like to know where to start exactly.
Where would I find what IC chips I need exactly and if I need any other resistors or fuses and what kind?
What other tools do I need in order to do this?

Can somone please be kind enough to guide me through?

**lcaillo** · **08-16-08, 08:05 PM**

Start by reading the first 10 posts in this thread.

**nouseforaname** · **08-17-08, 03:46 PM**

Hello there. Thanks for your advice about the convergence. It's impressing how someone is detailed about the information they speak of so I appreciate it. I do have a question though. I recently purchased a Mitsubishi WS-55909 and I have no idea if the convergence is bad or not. I have to get it working first by the DM Module. But if the convergence is bad, what IC should I be getting for this set? I tried looking at what the IC looks like in the back of the tv but a mirror and light didn't really help. I'm just being cautious for the future or if the tv convergence is bad when I get it working.

**lcaillo** · **08-17-08, 05:39 PM**

You usually have to take the heat sink clip off of the Mitsubishi convergence ICs to see what they are. What makes you think that the DM is bad?

Please start a new thread for each set, and give details about the methods and findings of any diagnosis.

**nouseforaname** · **08-17-08, 06:01 PM**

You're right but since I'm new, I don't think I ca yet. The DM module is bad as the seller who sold me the tv set said this. They had it checked out by a service person and said it's the DM module. So I'm just going to repair it myself from the steps at HDTVoice. I don't really know if the convergence is messed up because it hasn't powered on yet. But if it is, I will follow your steps and repair it myself. I just see this talk about resistors and fuses and have no clue which resistors or fuses to replace if I replace the IC's. Sorry if this is off subject though. I'd just like to know because I followed a link to another site and it was selling two STK IC's, STK392-180 and STK392-180/O. The one with the "/O" is more expensive. I don't understand any of these terms so if possible, correct me, help me out if you can. Once again, sorry if this is the wrong place to post this. I'm just curious about the convergence issue if my set has one.

**lcaillo** · **08-17-08, 08:55 PM**

Look in the parts supplier thread for reliable distributors. There are lots of bad parts out there. If you want real information you have to be specific by giving details like the name of the distributor and the details of what the set is doing. Are you getting the flashing LED or is the set dead?

I suspect the "/O" means original, as in original Sanyo part, but this is likely specific to the vendor, and you did not give that information.

There is no way to know if you have a convergence issue until you determine what the other problems are. Regardless please start a new thread.

**nouseforaname** · **08-20-08, 03:46 PM**

Alright. I installed the capacitors and my tv actually went on. I'm so glad. The convergence was off a tiny bit. Blue and red are perfect. I'm just concerned about the green. It looks off a little. What could that be?

**lcaillo** · **08-20-08, 10:53 PM**

Capacitors? After repair, it is typical to have to do some alignment. The green must be adjusted in the service menu. The red and blue can be touched up in the consumer menu.

**nouseforaname** · **08-20-08, 11:16 PM**

Yeah, I had to get it working, remember? My tv's working now and like I said the blue and red are perfect. The green could be fixed but I don't know how to get to it. How do I fix it myself? How do I get to the service menu? I should look this up. Thanks.

**lcaillo** · **08-21-08, 06:34 AM**

Ah, the DM caps. If you are going to do service level convergence, I suggest getting a copy of the manual so that you at least know where the adjustments are.

**nouseforaname** · **08-21-08, 01:11 PM**

I have the manual that came with the tv, I'm not sure if that's considered the service manual or not. Maybe it's just my eyes acting up on me but I'm not really sure. Where it shows the channel and if it's 480i or not, it's yellow originally but the green is coming off from the left of the words. I'd take a picture but I know it won't come out correctly. Maybe it's fine and I'm making a bigger deal of things.

**lcaillo** · **08-21-08, 01:21 PM**

What you have is the user manual and it will help you find the user level convergence which may be adequate. You will have to adjust the red and blue to match the green, however, as the green is fix at the consumer level adjustment.

**nouseforaname** · **08-21-08, 01:24 PM**

So what I have to find is the service manual, the one with all the codes as to if the led light starts blinking by code. I'd have to buy this manual? That's kind of odd how they never gave that away with the tv. I guess that's how the sellers would make money so when the tv does fail, the consumer wouldn't know how to repair it themselves.

**lcaillo** · **08-21-08, 01:45 PM**

It is not odd at all these days. A couple of decades ago manufacturers often included schematics with the set, but even then they never provided service training info. If you look you may find the manual online for free, or you may have to pay for it. Regardless, you can still complete a repair like this for under $100 even if you have to buy the manual and some tools. You are getting a lot of help for free. Never before has so much information been so readily available for novices to attempt such repairs.

**cwilliamrose** · **08-27-08, 03:40 PM**

lcaillo,

First, thanks for this forum and your effort to help people. I'm sure many would junk their old sets and buy a new one faced with an expensive repair. We are looking to replace ours with an LCD when the prices come down, in the mean time our old set should be good for a few more years.

We have a Mits WS65819 bought new about seven years ago. We had it professionally calibrated four years ago. About two months ago it started going out of convergence calibration after the set was on for a few minutes. It didn’t creep out of adjustment, it was digital – perfect or way off. At first a simple power off and on would bring it back. As time went on it took less time to develop the problem and more time before it could be "corrected". Sometimes it would correct itself.

These symptoms told me there were probably bad solder joints, but where? A search on the internet led me to several forums where my exact problem was being discussed. So I knew it was the convergence IC's. I also read that it's not wise to just repair damaged solder joints -- if the chips finally do fail they could take other components with them. I decided to replace the IC's. I felt I would find no bad resistors or fuses since the TV could operate normally for long periods of time once everything was up to temperature.

This is where I made a mistake. I hadn't found this forum yet, but the common wisdom was to buy Sanyo chips from a reliable vendor. Instead, I saved a few bucks and bought from Bluestar International. I also bought some 5A pico fuses just in case. Good thing I did.

I removed the main board and found ring cracks around most of the IC's pins. I was sure they were the cause of the in and out convergence problem. Since I had the new parts and I was reluctant to just re-flow the joints, I removed the old chips, cleaned everything up and inspected the board. Everything else looked good, no coolant leaks, burned resistors, etc. I carefully soldered in the new IC's and other than having a little trouble wetting the pins, it went pretty well. I reinstalled everything and fired it up. Rats!

The set powered up for two seconds, then shut off. I tried it again -- same result. Out comes the board and I inspect my work with a magnifier, not just reading glasses. I found no bridged joints, only a few joints that looked less than perfect. I carefully re-flowed those and checked the fuses. One was blown and I replaced it. Back in with the board, everything connected and checked. Fire it up -- same result, on for two seconds, then shut down. I stop working on it. I put the covers on to keep the cats out and I thought about what it could be that caused a problem beyond what I had to begin with. I figured I either trashed the board by working too long trying to wet those pins or I had bad parts. Trusting my soldering more than my cheap IC's, I ordered new IC's from MCM and waited. I got the parts and pulled the board. I went through the same removal and inspection process as I had done the week before. The board looked fine but that same fuse was blown again (no surprise since I didn't really "fix" anything since the first time it blew).

I did tin the pins on the new IC's before installation and that was a wise move. I believe they were tinned with lead-free solder and having them out and wiped with flux made it very easy to get a good base of solder on the pins. I did the installation as before, replaced the fuse and re-installed the board. This was going to be the last time I did this, I was going to call for help if this didn't work. Turn on the TV and wait two seconds, three seconds, four five six,,, It works! Bad Parts!! I knew it!!!

I got good advice and didn't heed it. My bad. Buy from a known good source. It's not the money, it's the lost time and the potential to damage what wasn't damaged to begin with. To their credit, Bluestar was glad I contacted them about my experience and apologized for the problems. They told me they had not had any reports of problems and mine was likely an isolated case. They told me to expect a full refund by tomorrow.

So, my masterfully calibrated TV is working but it's obviously out of calibration, it looked out of focus but I hadn’t looked at the convergence yet. I never attempted to adjust out my original problem but I wasn't surprised it had changed with the new parts. I did about 10 minutes worth of adjustments with the user level convergence menu and got it much better. I know the TV wasn't warmed up fully (maybe 30 minutes) and the parts were brand new. It's been used about 20 hours now and I will do another round of adjustments after a two hour warm up. I think it will be fine after that.

Would you expect anything else to be off with the new parts? I noticed some distortion in the very lower left corner but I need to do a full look with the calibration disk to see if anything else is visible. Could it be that that corner was sacrificed for the rest of the adjustments during calibration?

Thanks again lcaillo for this great service. .........Bill

**lcaillo** · **08-27-08, 03:58 PM**

The biggest source of variance when changing parts is actually wire dress. You need to verify that all of the wires are tied down as they were before, or at least secured and not near high voltage, deflection wires, nor heat sinks. Then you can do convergence and focus. You will need to start from scratch and do it from the service menu if you want to do it correctly. Make sure no controls are adjusted to extremes.

Your experience is exactly why I created the thread. Even lots of professionals have benefited from the info here and avoided the wasted time that comes with bad parts. I have seen too many people go this route, both in the DIY world and among professionals. Thanks for your comments and glad to help.

The sad truth is that you got bad advice when you were told not to just resolder the chips. Virtually all of the convergence repairs I do on these sets have been just resoldering them. If you catch them early enough there is not a problem. Also, the most common parts to go in addition to the chips are just the pico fuses. These sets almost never eat resistors nor power supply regulators like some might. The sets are pretty well protected so that when a supply drops (or increases) it will go into shutdown to protect from such damage.

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