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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Sharp 61" RPTV shutting off
I have a Sharp RPTV, model # 61R-WP5H, 61", about 6 years old.
For the past 6 months or so, it will work for random lengths of time. Sometimes 6 hours, sometimes 3 weeks. Eventually, the image will collapse & disappear into to bottom center of the screen, and the audio disappears about 2 seconds later. The power LED shuts off & the LED next to it (status?) begins blinking twice every 1.4 seconds. Unplugging the set for awhile will make it come back, again for a random amount of time. Eventually it happens again. Lately it's gotten worse, lasting no more than 30 minutes before shutdown. According to the service manual, 2 blinks every 1.4 seconds indicates that the "vertical output protector circuit" is not detecting any vertical output. Without this protection, the image would collapse into a single horizontal line across the screen. Next to that, it shows a diagram of " IC501 " monitoring the vertical output as a 14V signal. The parts list in the back describes everything beginning with "IC" as an integrated circuit in the form of a chip or a voltage regulator. So my goal was to locate " IC501 " and find a loose solder joint somewhere in it's vicinity. Problem is, " IC501 " doesn't seem to exist. It's nowhere on the indicated circuit board, nowhere in any of the schematics or PCB drawings, and nowhere in the replacement parts list. I've found other IC's with similar numbers (IC601, IC6501) but all are described as something different on the schematics. The printed circuits on the board in question are large enough for me to repair with the soldering equipment I have. But it's a big board, and I just want to narrow down the location. Putting the PCB assemblies back into the set & reconnecting everything in order to test takes about a half hour, and I'd hate to have to do it more than once or twice. Any direction would be appreciated. |
#2
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Sharp 61" RPTV shutting off
On Sun, 23 Dec 2007 12:00:48 -0500, Meat Plow
wrote: On Sun, 23 Dec 2007 15:22:52 +0000, D&K wrote: I have a Sharp RPTV, model # 61R-WP5H, 61", about 6 years old. For the past 6 months or so, it will work for random lengths of time. Sometimes 6 hours, sometimes 3 weeks. Eventually, the image will collapse & disappear into to bottom center of the screen, and the audio disappears about 2 seconds later. The power LED shuts off & the LED next to it (status?) begins blinking twice every 1.4 seconds. Unplugging the set for awhile will make it come back, again for a random amount of time. Eventually it happens again. Lately it's gotten worse, lasting no more than 30 minutes before shutdown. According to the service manual, 2 blinks every 1.4 seconds indicates that the "vertical output protector circuit" is not detecting any vertical output. Without this protection, the image would collapse into a single horizontal line across the screen. Next to that, it shows a diagram of " IC501 " monitoring the vertical output as a 14V signal. The parts list in the back describes everything beginning with "IC" as an integrated circuit in the form of a chip or a voltage regulator. So my goal was to locate " IC501 " and find a loose solder joint somewhere in it's vicinity. Problem is, " IC501 " doesn't seem to exist. It's nowhere on the indicated circuit board, nowhere in any of the schematics or PCB drawings, and nowhere in the replacement parts list. I've found other IC's with similar numbers (IC601, IC6501) but all are described as something different on the schematics. The printed circuits on the board in question are large enough for me to repair with the soldering equipment I have. But it's a big board, and I just want to narrow down the location. Putting the PCB assemblies back into the set & reconnecting everything in order to test takes about a half hour, and I'd hate to have to do it more than once or twice. Any direction would be appreciated. Component grid numbers are usually grouped by circuit function. I say usually because this is my experience, others may or may not agree. What I mean by grouping is that an IC in the vertical may start with IC5xxx, horzontal IC6xxx and so on. Same with say resistors (R5xxx, R6xxx) Things to check: Make sure you have the exact service literature. Try to find other ICs or components grouped together with the 5xxx number. That's about it for me I thought that might be the case. I've found the 2 zener diodes also shown in the diagram, but the mentioned IC is nowhere around. I also found what appeared to be a loose solder joint on a capacitor nearby, and resoldered it. I just want to exhaust any possibilities before reassembling everything. Thank you for your help. |
#3
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Sharp 61" RPTV shutting off
"D&K" wrote in message ... I have a Sharp RPTV, model # 61R-WP5H, 61", about 6 years old. For the past 6 months or so, it will work for random lengths of time. Sometimes 6 hours, sometimes 3 weeks. Eventually, the image will collapse & disappear into to bottom center of the screen, and the audio disappears about 2 seconds later. The power LED shuts off & the LED next to it (status?) begins blinking twice every 1.4 seconds. Unplugging the set for awhile will make it come back, again for a random amount of time. Eventually it happens again. Lately it's gotten worse, lasting no more than 30 minutes before shutdown. According to the service manual, 2 blinks every 1.4 seconds indicates that the "vertical output protector circuit" is not detecting any vertical output. Without this protection, the image would collapse into a single horizontal line across the screen. Next to that, it shows a diagram of " IC501 " monitoring the vertical output as a 14V signal. The parts list in the back describes everything beginning with "IC" as an integrated circuit in the form of a chip or a voltage regulator. So my goal was to locate " IC501 " and find a loose solder joint somewhere in it's vicinity. Problem is, " IC501 " doesn't seem to exist. It's nowhere on the indicated circuit board, nowhere in any of the schematics or PCB drawings, and nowhere in the replacement parts list. I've found other IC's with similar numbers (IC601, IC6501) but all are described as something different on the schematics. The printed circuits on the board in question are large enough for me to repair with the soldering equipment I have. But it's a big board, and I just want to narrow down the location. Putting the PCB assemblies back into the set & reconnecting everything in order to test takes about a half hour, and I'd hate to have to do it more than once or twice. Any direction would be appreciated. Ignore the numbers for now and just look for the vertical output IC. Most of them look pretty similar, 5-8 legs, small package mounted vertically to a heatsink. You can follow the traces from the yoke plugs if you need to. |
#4
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Sharp 61" RPTV shutting off
On Sun, 23 Dec 2007 13:18:12 -0500, Meat Plow
wrote: On Sun, 23 Dec 2007 17:32:52 +0000, D&K wrote: On Sun, 23 Dec 2007 12:00:48 -0500, Meat Plow wrote: On Sun, 23 Dec 2007 15:22:52 +0000, D&K wrote: I have a Sharp RPTV, model # 61R-WP5H, 61", about 6 years old. For the past 6 months or so, it will work for random lengths of time. Sometimes 6 hours, sometimes 3 weeks. Eventually, the image will collapse & disappear into to bottom center of the screen, and the audio disappears about 2 seconds later. The power LED shuts off & the LED next to it (status?) begins blinking twice every 1.4 seconds. Unplugging the set for awhile will make it come back, again for a random amount of time. Eventually it happens again. Lately it's gotten worse, lasting no more than 30 minutes before shutdown. According to the service manual, 2 blinks every 1.4 seconds indicates that the "vertical output protector circuit" is not detecting any vertical output. Without this protection, the image would collapse into a single horizontal line across the screen. Next to that, it shows a diagram of " IC501 " monitoring the vertical output as a 14V signal. The parts list in the back describes everything beginning with "IC" as an integrated circuit in the form of a chip or a voltage regulator. So my goal was to locate " IC501 " and find a loose solder joint somewhere in it's vicinity. Problem is, " IC501 " doesn't seem to exist. It's nowhere on the indicated circuit board, nowhere in any of the schematics or PCB drawings, and nowhere in the replacement parts list. I've found other IC's with similar numbers (IC601, IC6501) but all are described as something different on the schematics. The printed circuits on the board in question are large enough for me to repair with the soldering equipment I have. But it's a big board, and I just want to narrow down the location. Putting the PCB assemblies back into the set & reconnecting everything in order to test takes about a half hour, and I'd hate to have to do it more than once or twice. Any direction would be appreciated. Component grid numbers are usually grouped by circuit function. I say usually because this is my experience, others may or may not agree. What I mean by grouping is that an IC in the vertical may start with IC5xxx, horzontal IC6xxx and so on. Same with say resistors (R5xxx, R6xxx) Things to check: Make sure you have the exact service literature. Try to find other ICs or components grouped together with the 5xxx number. That's about it for me I thought that might be the case. I've found the 2 zener diodes also shown in the diagram, but the mentioned IC is nowhere around. I also found what appeared to be a loose solder joint on a capacitor nearby, and resoldered it. I just want to exhaust any possibilities before reassembling everything. Thank you for your help. You're welcome. Hope you resolve the problem and I don't blame you for not wanting to leave no stones unturned. If you've identified where the vertical components reside a good scan underneath for bad solder joints is a great idea. I've done this countless times even using a stereo magnifying visor. Resoldering that joint didn't work, it still shuts down. I did manage to identify the vertical IC, but there's not a bad joint anywhere near it. So, what can cause the vertical signal to just randomly stop? I'm not sure what else to try here. |
#5
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Sharp 61" RPTV shutting off
Resoldering that joint didn't work, it still shuts down. I did manage to identify the vertical IC, but there's not a bad joint anywhere near it. So, what can cause the vertical signal to just randomly stop? I'm not sure what else to try here. Some bad joints are hard to spot, I would try prodding the board with an insulated stick with the set on. I would also look at the power supply. If it is determined that a solder joint isn't the problem, the next thing I would do is check for marginal capacitors. |
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