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Any tips on how to work without a schematic. Have been trying to get one for a Sanyo Color TV Model # 62C915U which has a problem in the vertical circuit (bright horiz.line). I'm unable to identify the circuit. There is a small circuit board attached to the pix pins which has 3 power amps (C2621 - Nte replacement 157) which I presume to be the deflection circuits. How to tell which are vertical and which horiz. is my problem.
Nope the virtical ouputs are not on the back of the tube.
The virtical ouputs are somewhere on the main board. Follow the leads from the deflection yolk (that electromanget looking thing that is around the neck of the tube) to the board. The virtical ouputs should be somewhere near where it conects to the board.
It is usally two transistors mounted on some sort of heat sink and a T0-3 type package, more modern sets may use a power IC simmilar to what you would find in a cheap audio amp. The horizontal ouput is the one transistor near the high voltage transformer you my find this one too when you follow the leads as they are often bundled together
Thanks very much for your suggestions which are most appreciated. I don't have any TO3's on the main circuit board, just the three TO220's on the neck board. BTW what are these power transistors for? I've got a few IC's on the main circuit board so will try to google them out, but don't have much hope. This set was mfd. circa 1990 and has given great service except for the present complaint.
The three transistors on the board one base of the tube are the color drivers. One each for the red, blue, and green CRT gun. They have nothing to do with scanning. Now if if you hade a picture but were missing just Green that would be a good place to start. But your problem lies in the deflection curcitry.
CRT's larger than a few inches use magnetic deflection to scan the screen. So circuitry involving horizontal or virtical deflection would be on the main board not on the board plugged into the tube.
Again the follow the leads from the deflection yoke to the main board then follow the traces. Should lead you right to whatever output device(s) they are using.
Early 1990's you say... could eaisly be surface mounts. I remeber a certain few models of Sears TV's in that era had their virtical ouputs on a little board that stood up off the main board. They were a larger surface mount package (the size of a T0-220 with no tab or legs) and would get so hot the solder would flow off leaving just a white line as you have. The transistors were still good and could be resoldered.
Thanks again for all the trouble you've taken. Being an oldtimer long retired, who was more comfortable with tube and early transistor jobs, I will wait till one of my grandsons visits to help me move the set around so I can do the suggested tracing. Oh for the good old selenium rectifier days lol. BTW If I can figure out how,I could include some camera shots next time.
Oh for the good old selenium rectifier days lol.
You can relive the good old days complete with toxic gas emission on burn out.
Only 75 Cents each at Surplushed
Thanks for the reminder - at least you could smell them when they went wrong.
I found a 13 pin IC (similar to TDA 2653A) in the V output. Its a through hole job so the solder pads are under the board so unaccessable for testing in a live circuit unless one had a schematic to show the above board related circuitry. Since I've now given up on trying to get any such animal I've decided to put it in the garage for now and get off your back. I don't like pulling the IC which may be fine, since related circuitry from the Integrator to the output could be at fault.
When that happened to us years ago the repair man came to our house with a cap and a soldering iron. He knew exactly which cap to replace just from the model of the TV before he got to our house :)
FWIW the old cap was obviously "bald" (i.e. it's can was domed tho it started out flat) and it was right on the card that plugged directly on to the back of the CRT.
Thanks for your suggestion. I already replaced an exploded small cap on the small circuit board which didn;'t help. Appears to be transistor trouble so back to square one.
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