The bottom 4 inches of the screen is displayed at the top of the screen and flipped upside-down!
This is caused by a bad capacitor in the vertical circuit. If you can solder, you may be able to resolve this yourself. If you wish to attempt this repair, please update this and I will provide additional details and instructions.
Dan
OK. Realize that there are potentially dangerous high voltages inside the set even when the set is unplugged.
With the set unplugged and the back removed, look for the vertical IC. This should be a small flat IC attached to a heat sink and should have about 9-11 pins. It may be marked LA7837 or something similar. If you are not sure you have the correct one, post the marking on the IC here and I'll confirm. Pay particular attention to the circuit designation marked on the board for that IC. It should be ICyxx. The yxx will indicate the circuit. Next look for capacitors with similar designations like this: Cyxx. The capacitor in question here should be a 100ufd value. I would change any capacitor in the vertical circuit in that range.
Let me know if that resolves the problem. It may not, but will at least change the symptoms which will help point to the remaining defective parts,
Dan
Sorry I may have confused you a bit here. The Cyxx would look like C301 or C313. The reason for the yx is that the y number usually means the circuit number while the xx means the part within that circuit. For example, the vertical IC may be IC301. The capacitors in the same circuit would be marked C3xx.
Sorry about the confusion. Also, the IC in question here will be attached to the heatsink with 1 screw. You should be able to see the marking on the part. Post those markings here.
Dan
Its hard to tell from the photos, but I think it is the one toward the front of the set from the Flyback transformer. Remove the screw from that IC and post the marking on the IC here. I will confirm that it is the correct one.
Dan
The LA7840 is the one. Look for capacitors in the same circuit and test/change them. Report back with the results.
Dan
Correct.
The controls on the back of the flyback are for focus and screen. There is no need to touch these at this time. These will have no effect on the vertical at all. Of the caps you list, the 100ufd is the most likely along with the 2.2ufd. There are others in the same circuit that are located relatively close by and another located by the large IC in the center of the board. I think that one is around 1ufd. That too may need to be changed.
Dan
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My Tv has a black line on top and bottom how can i repair it, which components are responsible?
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I can solder! I would greatly appreciate your help.
I'm going to grab a bite to eat, then open the TV. I will let you know within the hour what I find. Thanks again. I do work on computer circuts at my job, but have never opened up a TV.
There are 3 circuit boards. One on the back of the CRT called "CRT socket PB ***'y," another called "power PB ***'y," and one large one that looks like it is the main board without a title. This main board is the only one with a heat sink. The only label for the heat sink seems to be "IC921." I am looking for a Cy designator, but have not found it. I will keep looking.
***'y = a s s ' y = assembly!
IC421, IC921, IC602 are the only circuits with a heat sink. I am still looking for "y" designators.
I'm still learning, so bear with me! Here are the marked off portions of the main board: MICON, BBE, MTS, AMP, POWER, AUDIO SWITCH, VIDEO SWITCH, TUNER, Y/C SWITCH, 1 CHIP IC, 3L DIGITAL COMB FILTER, AUDIO AMP, H.DEF, AV IN
There are four heat sinks and they are all attached by one screw. I listed all of the IC numbers associated on a previous post with exception of one in the bottom right which I could not find an ICxxx. I hope these photos help, I had to reduce them to upload on this site. I will make another post with a close up of the heat sinks.
Thanks again for helping me, I know it can be difficult when you can't be here to look at it.
STR-30134-1809
LA7840 1S 8
D2499 1:G
IC421 is the one toward the front of the set from the flyback. I may be confused which one you mean. Are you talking of the black one, second to last photo posted?
LA7840, Okay, we are talking about the same one. So I should be looking at all of the capacitors "IC4xx," right?
I didn't notice before, but I found two dials on the back of the flyback transformer. I don't want to plug-in the TV to try them out unless you think it is worth it. Do you know what they are?
I found four capacitors with C4xx. They are:
C424 - 100uF, 35v
C425 - 470uF, 35v
C427 - 2.2uF, 50v
C428 - 220uF, 25v
You fixed it! Because I bought the wrong size capacitor for one, I ended up only changing three of the four capacitors (and I found a fifth).
I changed:
C424 - 100uF - 35v
C425 - 470uF - 35v
C427 - 2.2uF - 50v
and I did not change:
C428 - 2200uF - 25v
C437 - 10uF -50v
I also found a problem I am certain I had before and just didn't pay much attention. There are fine horizontal lines spaced about every 1/2 cm that scroll down the screen. It is easy to ignore, I think I just notice it now that I am scrutinizing the screen! I am tempted to just leave it as is, but if you have any suggestions, I will take them.
I played around with the dials on the flyback and now I see what you were talking about. The display is now clearer than it was before thanks to that.
Thank you. This was a fun project. We've been spending so much money preparing for our baby to come in the next month that it is nice to be able to save some money with this fix.
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