rventena
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Dec 26, 2019, 3:45 AM
Post #5 of 6
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Re: [jts1957] Panasonic CT-32SF37SB CRT TV
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UPDATE: (unnecessarily lengthy examination below, heh)
Hello all, I have not forgotten this thread, just been busy for these past 1.5 years, but I finally had the desire & itch to open this TV again these past couple weeks. Well actually I've been wanting to since the last time I opened it in 2016, heh. So it was just as recent as early last yesterday morning, around 3am, I got my courage up & proceeded. First had to lay the damn heavy thing on to its face but then I lost grip just past the middle of the distance to the floor. My heart jumped, but luckily I had put some foam down or surely the glass would have cracked. Slid the motherboard out of its slot & looked all around. I never found any service manual, so I was sort of doing this blind. The information I got from this thread was all I had going.
So there were several regulator-type IC's with attached heatsinks on the main board plus a couple more on the CRT neck PCB, probably nearly 10 chips total (didn't exactly keep count). I tediously looked at all their pins on the solder side with a head-worn stereoscopic magnifier (it's my dad's, he was a physician). I could not find anything unusual on all of them, until I came upon a 12-pin single inline chip. All the pins had the nice tapered solder on them (tapered from top of pin & curves all the way down spread around the pcb solder point) until I noticed pins 9 & 10. Both did not have that normal melted tapered look, they looked oddly more like blobs hanging on the pin but not quite touching the pcb. Well, I looked up this part, an AN5277, which says this is a dual channel sepp power amp & pins 9 & 10 are ground & Vcc. So how could a possibly open Vcc & Gnd pins on an audio power amp affect the picture? I did not want to do a continuity check on the pins, so I just went ahead & reflowed/remelted all 12 pins on this chip. Come to think of it, I decided to solder reflow all the pins on all the heatsinked chips, including the ones on the neck board, & whatever else I could find. Again this came to about 10 chips. There's also the fact that I could not see the part numbers on the other chips because I did not undo all the wires to totally free up the board, not to mention some/all of them have their heatsinks attached on the side of the chip where the part number is located. AN5277 was near the edge of the board so could easily see the part number on the chip.
The reason I didn't do a powerup check right after I just reflowed the AN5277 is because the TV is face down & it would be tiresome to keep lifting it up & then back down & then up etc until I got to the right chip that had the problem. It was also "late" & I had to get to sleep. So I did everything all at once, closed the case back, levered TV up carefully, turned it on, & holy smokes, the usual white static picture came up with menu captions. It worked! Finally, after 3-4 years dead.
So where was the culprit? I will never know because I was rushing it, redoing the solder on all the regulator-type chip pins simultaneously. Best guess is that AN5277 Vcc & Gnd pins, but not sure why that would matter??
Anyway it's done, this machine should work for another 20 years until the same issue resurfaces or something else bad shows itself. Perhaps my dad's spirit helped me, who knows. The only other thing is that someone else in the family doesnt really want this TV anymore because it really is heavy, compared to a modern flatscreen bigger than this that's easily carried by one person. But now that this family member is surprised I got this TV working again, I wonder if it will change perspective, because this TV does partly symbolize the years we had with dad still alive. Anyway will have to see. Thanks to jts1957 for the help last year.
Also, is it ok to ask about computer monitors or is this place just about repairing TV's?
Merry Xmas & Happy New 2020. Until next time. :)
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