blue crt in and out of focus

**bostrack** · **06-10-09, 01:13 AM**

Great Forum, wish I'd found it earlier.

Problems with a Samsung RPTV HCR4755wx/xaa

My problem started with horizontal red lines about an inch apart on the screen after warm up, a flickering red crt and a dark picture with a red tint. Could not adjust this out with the focus pack.

I have replaced the flyback, and the HV distributor (Because throwing parts is what you do when you don't know what to do). No effect.

I replaced the crt drive cards (they came as a set) which seems to have corrected the red flicker and lines.

Now I have a blue that seems to be hunting in and out of focus. It seems to click into sharpness with an audible click that comes through the speakers, then slowly fades back to a blur. Frequency of this effect is random and variable maybe 5-30 seconds after the set has warmed up.

I suspect from what I have read there may be a problem with the convergence ICs. I have not yet replaced them.

Could they have caused the drive cards to go bad, or vice versa.

Hey, I even happen to own a scope, although, I have yet to use it and wouldn't know where to connect it. Just thought I'd throw that in just in case some one was thinking "...well, if he had a ..."

Thanks

**bostrack** · **06-11-09, 01:40 PM**

And another question...It looks like I'll have to go through a complete service level convergence and geometry rebuild. I've dinked around with so much stuff. Including the (yokes?) I have the service manual, but the instructions in the alignment section seem to leave out information, stuff that may be obvious to an experienced service tech, but not so obvious to me. Has anyone seen a thread about how to do this, especially on a Samsung?

**lcaillo** · **06-13-09, 07:45 AM**

You need to be careful not to confuse focus and convergence problems. Focus is how well the beam is maintained and affects the detail that each tube can dsiplay. You will see focus effects in a single tube, though they will also be apparent when all three are displayed. Convergence is not focus, though it does affect the clarity of the image when all three images are displayed. Convergence is the alignment of the shape and size of the three images relative to each other.

Your thread will be moved to the Samsung forum to maintain forum organization and to make information easier to find. You may find posts there that help you sort out your alignment issues. If you have questions, make them specific, and I will try to answer them if I recall or if the information is generic and applies to many sets.

**bostrack** · **07-20-09, 04:41 PM**

So, still stuck, and tired of throwing parts at it. Right now, when I turn on the set, the picture frame which is skewed at an angle, scrolls horizontally, at varying speeds. It will start scrolling to the right, quite fast, then gradually slow, change direction, and start accelerating in the other direction. I never do get a static picture to work on. Any ideas how to overcome this problem, so hopefully I can move on to others.

Thanks

**lcaillo** · **07-21-09, 04:46 AM**

Now you are describing what sounds like a sync problem. This is very different than a focus or convergence problem. Before getting any help, you need to be able to describe the symptoms with more clarity. Posting images might help.

**thewire** · **07-21-09, 10:33 AM**

Sounds like the Service board to me.

**lcaillo** · **07-21-09, 12:48 PM**

What is a service board?

**bostrack** · **07-21-09, 01:38 PM**

Really?

I have described the problems I have as specifically as I can with the non television repair vocabulary that I have. Yes I have a convergence problem, yes I have a focus problem as well, probably both self inflicted at this point because I've been screwing around with the yokes and the service convergence menu.

Earlier I had a problem with the horizontal red lines and a flicker that I described in detail. Replacing the drive cards seems to have made it go away.

On 6/9, the picture frame was not moving, I was trying to adjust the convergence and the focus and could not get results due to the problem with the blue that I described in detail in that post.

Right now, yes it seems like I have a horizontal sync problem, but have no idea what controls that, or how to fix it. When the picture is moving sideways at ten frames a second, it makes the focus and the convergence really hard to adjust, so I guess I'll worry about those later.

Could someone give me a hint of something useful to test or adjust or replace, or ask me a useful diagnostic question or something? I'm quite sure that the problem with my TV is not that I am describing the picture incorrectly.

Thanks

**thewire** · **07-21-09, 02:07 PM**

Quote:

lcaillo wrote:

What is a service board?

The thing that stores the info when it's not plugged in.

**lcaillo** · **07-21-09, 08:35 PM**

We are really beyond the scope of the forum. Troubleshooting sync problems requires troubleshooting skills, a scope, and signal generator. I suggest that you review what you have done, as the problem likely results from something done in servicing the set if it did not have the problem when you started.

**bostrack** · **09-28-09, 07:01 PM**

Back to this.

So horizontal sync problem solved! Won't go into it, off topic. I'm back to a stable image that I can deal with and hopefully converge at some point once I get this blue issue resolved.

So, I am back to the original problem that prompted this thread.

My blue is blurry, but not stable. The Blue will "pop" into sharpness as if being corrected by some control influence, on its own frequency (maybe every few minutes? it is not constant), then slowly fuzz back into obscurity. I conclude therefore, it is not the optics which have only a manual adjustment. Also I have not monkeyed with the yokes on this tube, they remain glued in their factory setting with the adhesive glop they use for such things.

Any ideas what may be the problem?

Thanks

**lcaillo** · **09-28-09, 07:15 PM**

My guess would be a bad connection on the anode or a bad focus divider. You can isolate the latter by swapping wires on the back.
Posted via Mobile Device

**bostrack** · **11-03-09, 10:27 PM**

After a short Hiatus, the problem outlined in the post from 7/20 above has returned. Anyone have a manufacturer for the part Q402, I believe this to be the HOT; it tests bad. The markings are F04 and D73-Y. It also has a stylized letter F that appears like it might be a logo for the manufacturer.

Thanks

**lcaillo** · **11-04-09, 06:53 AM**

How does it test bad if you don't know what it is? If your HOT was bad you would likely get no sweep at all and the set would be in shutdown. Do you have a service manual? Have you considered the suggestions in earlier posts?

**bostrack** · **11-04-09, 10:17 AM**

Wow you really aren't interested in helping much are you?

It tests bad because I removed it from the board, and is is open in both directions.

Yes I have a service manual, not a very good one as it does not list the component, only the board level assembly.

If you wanted to help, you could confirm that Q402 is indeed the hot, or tell me where I could find a replacement, like I asked, but I don't think you have any real interest in helping.

As far as following suggestions, the only one you've given was not for this problem. Usually you just criticize my description of the problem. Go back through your posts and give me one example of a useful suggestion other than 9/28. Which I did check at a point, but not related to the current issue.

If anyone else actually reads this forum, which I doubt, because you are the only one that answers, I'm sure they'll agree.

Thanks for nothing, again...

**lcaillo** · **11-04-09, 10:42 AM**

If I was not interested in helping, I would not respond, nor put in the many hours that I do each week answering questions on this forum. Please note the dozens of people who have been thankful for the help that they have received here. Your comment is offensive and indicates little respect for the value of the forum. If you are unhappy please cease posting and search for help elsewhere. You get a lot more than you pay for here, and if that is not sufficient, frankly, no I am not interested in helping ingrates.

The scope of this forum does not include doing specific research on the circuit for your set. If you have the service manual you can do that yourself, as the information IS there if you have the complete manual from Samsung. The forum is intended to provide general information, common symptom-repair relationships, and background information. Specific research and troublehooting are not practical and simply require too much time to give away for free. There are professionals available to do that kind of work if you are not capable yourself or are unable to learn what you need from the information and links provided. I will also provide such services for a fee by email, in person, or by phone, but I do not advertise it on the forum.

What does open in both directions mean? A transistor is tested like you would a diode, and it should forward bias at both junctions at somewhere around half a volt. Some HOTs have internal damper diodes and/or resistors that cause the base to emitter to read a fairly low resistance. Generally, transistors fail as a short, not open, particularly high current devices like an output transistor.

As I also said, a bad HOT would almost never cause sync issues. If you would post images like I suggested, and provide more detailed and accurate information about the conditions, problems, and solutions that you think you have, you would likely get more help. If you just want to complain, please go somewhere else.

**tonyvdb** · **11-04-09, 11:49 AM**

Daniel, with all due respect. You are the one who is not cooperating here Icaillo is "the" guy to go to if you want decisive and clear answers to these sorts of questions. He is a service tech by trade and has been doing so for many years if he cant help you then I doubt anyone can.

**Sonnie** · **11-04-09, 03:22 PM**

I agree. Reading from top to bottom, my first thought is you are ignoring lcaillo... as if you are talking around him. He has made suggestions and asked several questions, but all I see is sarcastic responses.

Anyone that doesn't believe that lcaillo does not want to help is either blind, can't read or insane. That is a general statement, not meant to offend, but all anyone has to do is read the MASSIVE amount of posts that lcaillo has offered up in helping others to know he is definitely one that wants to help others... AND we nor he charges anyone a dime for that help! We actually even give you opportunities to win several giveaways including cash... so in some cases not only do we offer free help, but it also pays to frequent the Shack. I am not sure it gets any better...

**bostrack** · **11-04-09, 03:43 PM**

Ok, what questions am I ignoring? I'll answer them.

**tonyvdb** · **11-04-09, 04:04 PM**

Quote:

bostrack wrote:

Ok, what questions am I ignoring? I'll answer them.

Each post you have made your problem has shifted dramatically in a different direction none have been related to the other. You said your self that you have been throwing parts at it but that seems to be fixing one thing and causing other problems every time you do something.
Slow down and lets start with what you have for a current problem and lets go from there Dont do anything until Leonard responds and do what he says.

**lcaillo** · **11-04-09, 07:48 PM**

Start by posting an image and describing the conditions. Are menus and on screen graphics affected, all signals, is the raster distorted or just the video? What did you do to resolve the problem previously? There are many questions that give context to a problem that we don't have not being there.

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