I know I have bad convergance chips but...

2199 Views 19 Replies 3 Participants Last post by lcaillo, Aug 29, 2009

jeffescortlx

Discussion Starter · Aug 21, 2009

I just picked up a Hitachi 61SWX12B, I dont know too much about the history of it. I got it cheap becuase it needs new STK392-110's and that's no big deal. But what I'm worried about is when I run the magic focus it starts with just red, it moves it around the screen like it should, and the shapes and text looks sharp and in focus. Then when it switches to the green, it looks blurry and does'nt seem to do any automatic adjusting like the red. (yes I know it wont move with bad STK's) and when it switches to the blue it's incredibly blurry, and also does'nt seem to move.

My question is, will bad STK's cause a tube to go blurry (besides not just converging)?

I have a feeling the original owner may have tried to "fix it" by adjusting thing's that should'nt be touched.

1 - 20 of 20 Posts

ljryjj

· #2 · Aug 21, 2009

If it's blurry, try optical focus(projector lenses) and electrical focus(focus block).
If it doesn't move, you need to double check your work, and make sure low ohm resistors are good.

jeffescortlx

Discussion Starter · #3 · Aug 21, 2009

Well I have'nt actully done any work yet. I'm thinking there is more then one problem with this unit, and it might be more then I can handle.
But I'd like to confirm that bad convergance chips can or can not cause the CRT tube to project blurry.
It's projecting out of focus, there is a chance the previous owner tried to "fix it" by adjusting the len's. Does this sound possible? Just the lens needs to be put back to the factory postion?
How can I find out more about this electrical focus block?

ljryjj

· #4 · Aug 21, 2009

Yes very possible.

Focus block: take the front speaker grill off, and then one blank panel off. Focus block has two rows(look for focus,screen, R,G,B signs).

Optical focus: There's a wing-nut on the projector lenses. Loose it, move left-right until focus is good, then tighten the wing-nut again.

jeffescortlx

Discussion Starter · #5 · Aug 21, 2009

ah yes, focus block. That must be what the little black box is with 6 knob's on it.
Original owner allready had the front panel off when I got there...I bet you he was messing with the Focus Block.
Thanks for the help, I feel a little better now. Cant wait to get home and adjust it to see if it clears up.

jeffescortlx

Discussion Starter · #6 · Aug 27, 2009

Got the focus problem under control (thanks by the way)...but I cant get the blue to move side to side. Up and Down works and the green and red are all moving just fine. (this is after installing new STK's)

I looked over the soldering, there are no pico fuses in the TV at all, just a couple of glass fuses. I ohm'ed out all the higher wattage resisters and compared the blue channel values to the other's.

Does any one know what color yoke wire is for side to side movment? That will help me back track the problem.

lcaillo

· #7 · Aug 27, 2009

Have you read the first ten posts of the convergence repair sticky very carefully?

Where did you get your chips?

Did you check the resistors with the yokes disconnected and the chips out of circuit?

Did you check d.c. offset at the blue horizontal input to the IC?

Refer to the service manual to figure out which wire is for each yoke, though I am not sure what you will be looking for. Yoke problems are very rare with these.

jeffescortlx

Discussion Starter · #8 · Aug 27, 2009

lcaillo said:
Have you read the first ten posts of the convergence repair sticky very carefully?

You bet I did.

lcaillo said:
Where did you get your chips?.

MCM, they told me they only carry Sanyo brand for that part number.

lcaillo said:
Did you check the resistors with the yokes disconnected and the chips out of circuit?.

Yes.

lcaillo said:
Did you check d.c. offset at the blue horizontal input to the IC?.

Nope, dont even know how to.

lcaillo said:
Refer to the service manual to figure out which wire is for each yoke, though I am not sure what you will be looking for. Yoke problems are very rare with these.

I'm not looking for yoke probelms, but It would be nice to beable to narrow down what of the 4 wires for the blue control the side to side movment.

lcaillo

· #9 · Aug 27, 2009

Did you get a Hitachi kit with the new ICs and the resistors from MCM? I was not aware that they sold them. If you replaced them with the 392 series parts that came in the set, you did not read the convergence thread very well. MCM was also suspected of having sold bad STK392-110 in the past, even though they claimed they were originals. More than a few vendors have had problems with bad parts in that series of chips and that is the reason for the limited number of recommended vendors in the parts post in the convergence repair thread. MCM is not one of them.

jeffescortlx

Discussion Starter · #10 · Aug 27, 2009

lcaillo said:
Did you get a Hitachi kit with the new ICs and the resistors from MCM? I was not aware that they sold them..

I did'nt need the kit, none of the fuses are blown, and I dont have any burnt resisters, they ohm out as they should.

lcaillo said:
If you replaced them with the 392 series parts that came in the set, you did not read the convergence thread very well. .

I read the covergence thread just fine. I know the 110's have been changed a few times to higher wattage ratings. I also read that most of the time changing the part number is a direct swap and does'nt have any side effect problems...most of the time. I wanted to replace with the exsact same parts number to lower the chances of compatibility problems. The first set of 110 lasted 6 years.

lcaillo said:
MCM was also suspected of having sold bad STK392-110 in the past, even though they claimed they were originals. More than a few vendors have had problems with bad parts in that series of chips and that is the reason for the limited number of recommended vendors in the parts post in the convergence repair thread. MCM is not one of them.

I'm going to be contacting them to see if they will do a swap.

lcaillo

· #11 · Aug 27, 2009

Hitachi specifically has the kits to upgrade to the improved version of your IC, the STK394-160. You should ALWAYS use the Hitachi kit if there is one for your chassis. The new chips are not higher power but are more reliable and more efficient. Hitachi stopped supplying the 392-110 long ago for a reason. They went to the 392-150, then to the 394 series which Sanyo claims to be more efficient. They seem to be very reliable compared to the earlier chips. I have never had one fail. The 392-110 was a troublesome and apparently often counterfeited part. I never use them at all any more unless there is some supply problem with the others.

Be careful that you do not have a charge on the circuit when installing new chips. If the set has recently been run, the power supply may still have charged caps and you can easily blow a chip installing them. Measure the voltage at the supply pins on the board at the chips to be sure.

Triple check those resistors. I have seen many repairs where someone thought they checked all of them and missed one. If you look in the .pdf files for the Hitachi kit for your set it will list the location numbers of the resistors that they supply. This will tell you which ones are important to check.

See less See more

lcaillo

· #12 · Aug 27, 2009

jeffescortlx said:
I'm going to be contacting them to see if they will do a swap.

Not sure why that would make sense. If you blew a chip yourself, they are not responsible. If they are selling bad parts, you don't want more of the same. You don't want to use that part anyway, since the new chips are available and improved.

jeffescortlx

Discussion Starter · #13 · Aug 27, 2009

lcaillo said:
Not sure why that would make sense. If you blew a chip yourself, they are not responsible. If they are selling bad parts, you don't want more of the same. You don't want to use that part anyway, since the new chips are available and improved.

Who said I blew it? You said your self they have been known to sell bad ones. There is'nt even any large cap's on this convergance board. And even if there was, the board sat on a shelf unplugged for a week.

lcaillo

· #14 · Aug 27, 2009

I did not say that you did, but it is always a possibility. I said that they had been suspected of selling bad STKs in the past, but I do not know that they are currently. I do not buy from them anymore for parts like this, and neither do most of the other techs that I know, so I have no way of knowing. I also said that the caps in the power supply can stay charged. If your set is one with the separate convergence board and you removed it, that changes the situation. If it was unplugged for a week, then that does not fit my description of "recently," either.

Please do not get defensive. I merely point out possibilities based on my experience. There are many ways that you can damage a chip, not just a charged supply. It happens all the time. A good tech always holds all possibilities open until something is shown to be fact. The vast majority of people who THINK they got bad parts actually missed something themselves. Assumptions are the source of mistakes for even the best techs, who frequently relearn that you have to be diligent in checking and rechecking the obvious.

We have already spent more time on this thread than it deserves. You used a supplier that was not among those recommended, and you used an obsolete part. At this point I suggest you remove the chips, test the supply voltages at the chips, test the d.c. offset at the inputs to the chips, then get the right kit, change the resistors supplied, verify your soldering and all connections to the chips and resistors, and heat sink the ICs properly.

All of this is covered in detail in the convergence repair thread, including suggestions about what to do if the attempted repair does not work. If you have questions about what is there please ask them. Otherwise, if you choose not to follow the suggestions and information that many hours of work go into preparing, there is not much more we can do.

See less See more

jeffescortlx

Discussion Starter · #15 · Aug 27, 2009

I know the part was obsolete when I orderd it. But I also know that part number lasted 6 years the first go around. So even if the replacment part of the same number only last half that, I'm still a happy camper. Then when that time comes, I will get the current part number.

You have to keep in mind, when i picked up this TV the original owner handed it to me in peices. He told me he tried to fix it. So I can only assume he turned every pot, dial & lens he could find. There is a good chance this set it too far messed up for me to fix it. If i cant get it to work, it's off to the garbage can. That is why I did'nt jump on the $100 hitachi parts kit, but instead the $13 110's.

I will test the power supplies, but dont all AMP's with in the package share the same + and - source? So if the Red and Green output's are working correctly in all directions, and they all share the same power supply, would'nt that rule out a power supply problem?

lcaillo

· #16 · Aug 27, 2009

Yes, that would LIKELY rule out a supply problem, but why would you not check at each pin to make sure that there are no broken traces or solder connections. You could ASSUME that it does not matter, or you can check it anyway, on the possibility that it does make a difference. There are multiple supply connections to the ICs and I believe that some of them make individual connections to the three op amps in the chip, but I am not positive either way. The point is, check and recheck everything, follow best practice, even when you think you don't need to. Or don't. These repairs are not rocket science, but many people botch them because they make assumptions.

Like I said before, follow the recommendations or not, but there are many years of experience and hundreds of these repairs behind them. Your set is not working after one attempt in which you did not follow the suggestions. I simply cannot spend any more time talking you through it. When you do what I suggested post the results. Or not. Your choice.

See less See more

jeffescortlx

Discussion Starter · #17 · Aug 28, 2009

lcaillo said:
When you do what I suggested post the results. Or not. Your choice.

welp, you were right. You can now go ahead and say " I told you so".
I checked the resistors for the 4th time. The blue channel resistor patten was out of order compared to the red and green, but any ways a 2.7ohm resistor opened up to 27ohms. What are the chances of that? lol. One color band off from being right.
Put in a 2.7 ohm, (left the MCM sanyo STK's in there) Had to do the magic focus twice, but the convergance is now dead on. Did'nt even have to do a service manual convergance.

But I got the focus and color as close as I can get it with being a noob (to undo what the previous owner did) . Looks pretty good for only having a 480p signal.

:jump::jump::jump::jump:

lcaillo

· #18 · Aug 28, 2009

Think about the time it took to respond to your posts, the time invested in the convergence repair thread, and how many times I have to answer questions that are already answered in detail in the thread and you will, perhaps, begin to understand why I sometimes ask myself...why do I bother?

jeffescortlx

Discussion Starter · #19 · Aug 28, 2009

lcaillo said:
Think about the time it took to respond to your posts, the time invested in the convergence repair thread, and how many times I have to answer questions that are already answered in detail in the thread and you will, perhaps, begin to understand why I sometimes ask myself...why do I bother?

You and me might be a lot more a like then you'd like to admit. I have been a moderator for a over-populated automotive forum for all most 10 years. Yes, 10 years of repeating my self over and over answering the same questions every time a new noob show's up. But, I do it because I like helping people, and I like to see people not be scared to jump in and make there own repairs with out having to pay a shop hundred's of dollars. Nobody is making you hit the reply button.
Thanks for your help.

lcaillo

· #20 · Aug 29, 2009

I have no problem admitting it at all. Other than that I don't debate points of repair with people giving me advice until I have done what I do with electronics, double and triple check my work, I suspect that you are correct.

Of course, the reason that I devote my time to the forums is precisely the same reason as you do. I like helping people, and I get a lot of help back. I have found lots of great info that helped me to repair my cars, appliances, and to do many other things that would have been harder to do without the contributions of people like you and me.

I love electronics and am fortunate to have been able to play with lots of the best equipment for many years, and to have had two careers that I love, in electronics and teaching. I satisfy much of the love for teaching on the forums and when I do calibration work.

1 - 20 of 20 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.