CRT based RPTV Convergence Repairs

[lcaillo]

At the top of this thread are some posts that I made that pretty much cover most of the generic information about convergence repairs that you need to know. If you have specific questions after reading that, regarding your situation and your set, please start a new thread. Include the complete model number and specifics about what you have found, done, and need. I will be glad to try to help if I can.

Would you be able to give me some idea on where I can locate the fuses in the power supply to the chips? It is a Philips 60PP9202.

[technoguy]

Hello lcaillo
I had reading this thread for quiet some time, I have a Sony KP 65 WS 510 and have a huge convergence problem with my set, Yesterday I replaced my STKs(392-560)and checked all my resistors and Ic outputs,but still have problems adjusting my Tv, What else I can do? Did I miss something?Thanks

[lcaillo]

Fast Hound wrote:

Would you be able to give me some idea on where I can locate the fuses in the power supply to the chips? It is a Philips 60PP9202.

Philips sets usually have pico fuses soldered into the board on the secondary of the main switching transformer in the power supply. They are often labelled on the board.

[lcaillo]

technoguy wrote:

Hello lcaillo
I had reading this thread for quiet some time, I have a Sony KP 65 WS 510 and have a huge convergence problem with my set, Yesterday I replaced my STKs(392-560)and checked all my resistors and Ic outputs,but still have problems adjusting my Tv, What else I can do? Did I miss something?Thanks

What kind of problem are you having adjusting the set? Do you have the documentation on the service menu? Do you understand how to align the convergence or are you just using the auto-convergence? The more information you include, the more likely you are to get a meaningful answer.

Please start a new thread with your individual problems.

Again, thanks. Upon checking the resistors I immediately found two of the six appear bad, #3155 & 3156. They are located right next to each other. They are discolored (brownish) and swollen in the middle. They would not even read on my ohm meter when the others were consistently the same.

What are the chances of this being the cause of the hour-glass picture?

Your explanation of the fuse location was greek to me, but I will do some research and find the location. Is there a recommended way of testing the fuse when I locate it?

[technoguy]

lcaillo wrote:

What kind of problem are you having adjusting the set? Do you have the documentation on the service menu? Do you understand how to align the convergence or are you just using the auto-convergence? The more information you include, the more likely you are to get a meaningful answer.

Please start a new thread with your individual problems.

Wow you're fast!
After the Stks got replaced I still have problems with the convergence and geometry on the set. A friend of mine told me that probably I have a blown fuse on G board(I'll check that tomorrow) but I still think I have something going on with voltage reg since I notice the red gun is upscale intermittent and wasn't doing that before.I can't do a auto convergence because it appear to have an empty memory,I did all factory reset on the svc menu (Thank God I bought the Svc manual and schematics) but still I don't know what else I can do.

[lcaillo]

Fast Hound wrote:

Again, thanks. Upon checking the resistors I immediately found two of the six appear bad, #3155 & 3156. They are located right next to each other. They are discolored (brownish) and swollen in the middle. They would not even read on my ohm meter when the others were consistently the same.

What are the chances of this being the cause of the hour-glass picture?

Your explanation of the fuse location was greek to me, but I will do some research and find the location. Is there a recommended way of testing the fuse when I locate it?

A fuse should read a short or very close to it. Really, if you need to be told this, your learning curve for this kind of repair is pretty steep and a Philips product is not one to be learning on. Be very careful! It may be time to get a professional to do this job.

[lcaillo]

technoguy wrote:

Wow you're fast!
After the Stks got replaced I still have problems with the convergence and geometry on the set. A friend of mine told me that probably I have a blown fuse on G board(I'll check that tomorrow) but I still think I have something going on with voltage reg since I notice the red gun is upscale intermittent and wasn't doing that before.I can't do a auto convergence because it appear to have an empty memory,I did all factory reset on the svc menu (Thank God I bought the Svc manual and schematics) but still I don't know what else I can do.

I do not understand "upscale intermittent."

One should NEVER do a convergence reset without a very good reason. You will find it very difficult to get it right again, and you are likely to overcorrect in some areas and drive the ICs very hard. Hopefully you did not save the reset condition and you may recover the data.

Please guys, start a new thread for your individual problems. It will be veryconfusing to ever go back and sort out what set is being discussed here if someone else wants to research something. You MUST read the posts at the top of the thread and you MUST be specific in your requests for help. A single thread for each problem keeps the forum much more clear.

Hello again lcaillo. I used the information in this thread to repair my Mitsubishi with success. I attempted the repair on my friend's Samsung with no luck. I replaced both the STKs and 4 resistors. Two resistors had burnt out the trace on the PCB. When I replaced the resistors, the trace tested good to the pin on the STK. Put everything together, and the convergence still could not be adjusted. The tv is a Samsung HCM5525W.

The convergence on this set is adjustable for all three colors. The green horizontal is the only one that responds. Verticle is a no go. The Blue and Red does not respond at all in either direction, up or down. I don't know what to do. Could you advise?

I have attached a picture as a reference.

Thank you.

[lcaillo]

Further repair would take some troubleshooting...at this point I would be verifying the info that you gave above and likely getting out my scope if it is correct. My guess is that you missed something in the repair, or perhaps you do not have complete info on how to adjust the convergence.

I will re-examine the board this weekend. Thank you.

I bought the repair kit from Tritronics for my Hitachi 53FDX01B. Originally my Blue was not a straight line in the convergence menu and the replacement parts removed the curve however the Blue Horizontal is now a diaginol line moving at a downward angle from left to right. The covergence screen does not allow me to straiten the line just move it up or down. Are there addtional options I can try to fix my problem.

I can't even find a certified Hitachi tech with in 25 miles of my house that makes house calls. I'm not dragging this thing to a shop.

Peter

[lcaillo]

What do you mean that the convergence screen does not allow you to stratighten it? What procedure are you using?

I have an RCA R52WH74 where the convergence has gone bad when then set was powered on.
I went to the menu setup page and the "convergence" option is no longer there. I have read that the problem could be a bad fuse(little brown block looking thing) somewhere. Or the problem could be the convergence IC STK392-040. On my model, I am not sure where these components (the fuse or ICs) actually are located...Can someone help me with the location?
Thanks
Rick

[lcaillo]

If a fuse has blown, it is unlikely that changing it will solve the problem. I am not very familiar with that convergence circuit, but if you look for the largest heat sinks, you will likely find the ICs if it has them. Some of the RCA sets have discrete transistors rather than IC outputs.

lcaillo wrote:

Further repair would take some troubleshooting...at this point I would be verifying the info that you gave above and likely getting out my scope if it is correct. My guess is that you missed something in the repair, or perhaps you do not have complete info on how to adjust the convergence.

The set I'm working on is a 55" Samsung HCM5525W. After taking it apart a second time, I closely examined the board around the STKs. I found two pico fuses that I hadn't noticed before. I found them by the marking on the underside of the board. They were both green and looked like resistors without the indentifying bands. I ohmed both of them, and one was open. It was labeled FD101S on my board. So I replaced it, and finally I was able to correct the convergence. The fuse probably blew when the STKs went out, and burnt the resistors.

For those who are having trouble correcting convergence after replacing the convergence ICs, look for a sine wave symbol on the underside of the board. That indicates a fuse, and is usually soldered on the board like a resistor.

Thanks again lcaillo!

nice write up!!

The line is not perfectly horizontal, it angles downward. I am in the customer convergence menu with the cross hairs using the remote to move the lines. Access by the convergence button on the TV's control panel.

If I move the line up or down it is still angled. Since the other lines are perfectly horizontal they can not lie on each other to create the white. Does the service menu offer addtional options.

[lcaillo]

Sounds like you moved the blue yoke. You need to get the service and training info to go through the convergence alignment. I don't recall on that unit specifically whether there is a tilt adjustment or not, but again, my guess is that you just twisted the yoke.

Brief story: got lazy, and got convinced to call repair shop (did not have schematics at time), after $400 and only one visit had the Magnavox 51MP392H/17 fixed with replacing the STK392-120s due to convergence issue. About 1 month went by and then (while watching) set would power down and after a few seconds power up, CRTs would start to illuminate then power off again. could only stop this by unplugging set. Now it became my challenge to fix. If this would have happened after I did the initial fix certain person with significant influence in household would have NEVER let me live it down. Got schematics (SAMS) started checking, replaced the power MOSFET, power control IC for the MOSFET and a few diodes etc.... no luck. Did not consider infant mortality initially but it was the problem, the STK392-120s needed replacement, the supply voltage as measured on the ICs never recovered as the set was trying to power up. As a result of checking for bad resistors, caps or open circuits I discovered the two STKs were not connected to the supplies as the schematic indicated. One had +35VDC, -35VDC and a -22VDC supply connection the other only a +35 and -35 supply connection. All supply voltages come from same winding (different taps) on transformer per the schematic. The discrepancy bothered me, decided to change board (removed existing jumper, installed "custom jumper" on pwb) so both STKs have 3 supply voltages. The two application notes on the data sheet (for the STKs) did not closely match the configuration in the set. Been working now for two months no problems. Bought the STKs from a site that promised genuine Sanyo parts I also recommend this. Now why post this.. 1) to share the experience. 2) possibly someone can answer the question was this modification I made good, bad or indifferent, and why. Do I recommend others do similar??, no not without further understanding of the longer term effects of the modifications I made.

[lcaillo]

My suspicion is that you did not modify the circuit at all. A problem on these sets that I have on these sets is that techs will crack a trace on the board. It was likely not easily visible or even just partly cracked when he serviced it, then with thermal cycling eventually cracked, trashing the chip. Could also be that he just used a cheap copy for the replacement parts. What you did should be fine if it conforms to the design intent for the IC.

The lesson that I would take from this is that there are lots of pitfalls with any repair. Be very careful not to damage boards and use known OEM parts unless there is a very good reason to do otherwise. Finally, never assume that mistakes are not waiting to happen with every action you take. One must be very careful working on these boards. Some of them can be very fragile. Some are well made and easy. Assume nothing.

Hello all
I am working on a friend's pioneer tv (don't have the model number) and the red convergence would not properly align. I have replaced the two STK392-110's with STK394-250A's (from ACME) and none of the color's will adjust now (previously, all were adjustable). All resistors are unburned and within spec, capacitors appear fine as well. The mute circuitry seems different, according to this thread as well as the datasheets. As I've read here, all colors bowed (as they now are) was attributed to no power to the STK's, but I would assume that the chip's output being muted would also cause the same problem? The 250A's datasheet states 'high' input on pin 2 for unmute, whereas the pcb has pin 2 grounded...Just want to make sure that cutting the trace and tying the pin to 5V may solve the problem, driving out to his house takes a while.

[lcaillo]

I do not recommend making modifications to the circuit. The STK392-110 should be replaced with STK392-150 or STK394-160, not the chip that you used. It is always best to use exact replacement parts. Pioneer replaced the -110 chips with the -150 and -180 versions. We know that the best solution is to use the STK394-160 from Hitachi and from using it in many other sets to replace the STK392-110. While the STK-394-250 appears to be the same except for the mute circuit, there is simply no good reason to take chances with circuit redesign in the field. Save yourself some headaches and get the right parts.

O.K. I've got the dreaded convergence problem on a Hitachi 53UWX10BA. Had it fixed (?) about 14 months ago and now it's back. Gonna give it a shot at fixin it myself this time and save myself 400 bucks ! I've ordered the parts already from Andrews and downloaded a schematic. My problem is that I'm not the most experianced person in the world when it comes to electronics. Fixin a car I can do but I'm a stranger to circuit boards and such. I know where the two STK 392-110's are but how do I know which resistors are the ones that are associated with them to replace ?