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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 Aquos LC20E1-S LCD TV Strange AC adapter
Hi everyone..
I recently got a Sharp Aquos LC20E1-S LCD TV. The problem is it didn't come with a power brick. The unit runs on 13VDC and uses 54W.. I managed to find a picture of the power brick for this TV and it has 3 seperate 13V connections to the board inside. I have checked the board with an ohm meter and they are completely seperated inside. One power wire goes to the audio amp, one to the tuner / lcd control board and one to the backlight inverter. I'm not really sure for the reason of seperating them, but I assume that it is for interference reasons and that the TV should power up if given 13V to all of those points even if from the same source. Anyhow I have tried powering it by tying all of the 13V+ togeather and giving them 13V and I get nothing except for a small noise from the speakers and a light very briefly turns on. Just enough to see it. Does anyone have any expirenence with this TV? I have a friend with the same tv.. Maybe I can borrow their AC adapter and try it on this one. Here is a pic of the same TV and the strange DC jack. "http://f11batchimg.auctions.yahoo.co.jp/users/1/7/7/3/reuse_store-imgbatch_1253519810/400x600-2009092100127.jpg" "http://tinyurl.com/knpq4t" Power brick "http://img193.auctions.yahoo.co.jp/users/4/3/3/2/smdtk695-img600x450-1253178530nulnxz50227.jpg" "http://tinyurl.com/m8wrv7" Thanks.. Mike |
#2
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Sharp Aquos LC20E1-S LCD TV Strange AC adapter
Michael Kennedy wrote in message
... Hi everyone.. I recently got a Sharp Aquos LC20E1-S LCD TV. The problem is it didn't come with a power brick. The unit runs on 13VDC and uses 54W.. I managed to find a picture of the power brick for this TV and it has 3 seperate 13V connections to the board inside. I have checked the board with an ohm meter and they are completely seperated inside. One power wire goes to the audio amp, one to the tuner / lcd control board and one to the backlight inverter. I'm not really sure for the reason of seperating them, but I assume that it is for interference reasons and that the TV should power up if given 13V to all of those points even if from the same source. Anyhow I have tried powering it by tying all of the 13V+ togeather and giving them 13V and I get nothing except for a small noise from the speakers and a light very briefly turns on. Just enough to see it. Does anyone have any expirenence with this TV? I have a friend with the same tv.. Maybe I can borrow their AC adapter and try it on this one. Here is a pic of the same TV and the strange DC jack. "http://f11batchimg.auctions.yahoo.co.jp/users/1/7/7/3/reuse_store-imgbatch_ 1253519810/400x600-2009092100127.jpg" "http://tinyurl.com/knpq4t" Power brick "http://img193.auctions.yahoo.co.jp/users/4/3/3/2/smdtk695-img600x450-125317 8530nulnxz50227.jpg" "http://tinyurl.com/m8wrv7" Thanks.. Mike So there maybe one or more floating voltages, you'll need perhaps 3 separate supplies and moulding up/exchanging for, your own connector -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#3
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Sharp Aquos LC20E1-S LCD TV Strange AC adapter
Snip
Here is a pic of the same TV and the strange DC jack. "http://f11batchimg.auctions.yahoo.co.jp/users/1/7/7/3/reuse_store-imgbatch_ 1253519810/400x600-2009092100127.jpg" "http://tinyurl.com/knpq4t" Power brick "http://img193.auctions.yahoo.co.jp/users/4/3/3/2/smdtk695-img600x450-125317 8530nulnxz50227.jpg" "http://tinyurl.com/m8wrv7" Thanks.. Mike So there maybe one or more floating voltages, you'll need perhaps 3 separate supplies and moulding up/exchanging for, your own connector Well for testing I just soldered all of the positive contacts togeather to one wire and the same for the neg and then soldered those to a barrel connector jack. It didn't let out any magic smoke when doing this so I guess it is okay still, although I'm unsure if it was working beforehand because I have no power supply. Mike |
#4
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Sharp Aquos LC20E1-S LCD TV Strange AC adapter
There are several reasons why Sharp chose to use three separate supplies.
One was to minimize the cost of a building a single "rilllly big" supply. The other is that it wanted to minimize the amount of bypassing and decoupling needed on the boards. The obvious answer to the question of why the set didn't work is that it doesn't "like" being driven from a single supply. (The original supply was likely missing because the was tossed out as defective (for whatever unknown reason)). I would not have plugged a single supply into it, simply on the (admittedly remote) possibility that it might be damaged. |
#5
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Sharp Aquos LC20E1-S LCD TV Strange AC adapter
"William Sommerwerck" wrote in message ... There are several reasons why Sharp chose to use three separate supplies. One was to minimize the cost of a building a single "rilllly big" supply. The other is that it wanted to minimize the amount of bypassing and decoupling needed on the boards. The obvious answer to the question of why the set didn't work is that it doesn't "like" being driven from a single supply. (The original supply was likely missing because the was tossed out as defective (for whatever unknown reason)). I would not have plugged a single supply into it, simply on the (admittedly remote) possibility that it might be damaged. Well if I were back home where I have a workbench and loads of wire and power supplies laying around I would have wired it up as it was intended. But unfortunately where I'm at now I don't many tools or parts to work with. Upon first looking at I thought they made seperate supplies just to save money on the design of the PSU and or for RFI protection. |
#6
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Sharp Aquos LC20E1-S LCD TV Strange AC adapter
Michael Kennedy wrote:
I recently got a Sharp Aquos LC20E1-S LCD TV. The problem is it didn't come with a power brick. The unit runs on 13VDC and uses 54W.. I managed to find a picture of the power brick for this TV and it has 3 seperate 13V connections to the board inside. I have checked the board with an ohm meter and they are completely seperated inside. One power wire goes to the audio amp, one to the tuner / lcd control board and one to the backlight inverter. I'm not really sure for the reason of seperating them, but I assume that it is for interference reasons and that the TV should power up if given 13V to all of those points even if from the same source. I rescued a similar set. The three supplies are, in fact, separate (common return). I didn't bother to sort out "why" as the set I have came with the brick. But, the schematic shows them as separate. Some possible reasons: - keep the backlight supply isolated from the signal processing supply (keeps audio/video cleaner) - make sure the "processor" power supply comes up before other supplies - allow the processor to run even if the other supply(ies) die (so it can blink an error indicator) - etc. Anyhow I have tried powering it by tying all of the 13V+ togeather and giving them 13V and I get nothing except for a small noise from the speakers and a light very briefly turns on. Just enough to see it. I'm not sure I would have arbitrarily tied all of the supplies together. There might be some power sequencing issues that your "patch" could make problematic. Of course, its too late *now*... : Does anyone have any expirenence with this TV? I have a friend with the same tv.. Maybe I can borrow their AC adapter and try it on this one. That's the *first* thing I would have tried (realizing that you *could* possibly toast their brick in the process -- so hope it is an understanding friend! : ) |
#7
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Sharp Aquos LC20E1-S LCD TV Strange AC adapter
"D Yuniskis" wrote in message ... Michael Kennedy wrote: I recently got a Sharp Aquos LC20E1-S LCD TV. The problem is it didn't come with a power brick. The unit runs on 13VDC and uses 54W.. I managed to find a picture of the power brick for this TV and it has 3 seperate 13V connections to the board inside. I have checked the board with an ohm meter and they are completely seperated inside. One power wire goes to the audio amp, one to the tuner / lcd control board and one to the backlight inverter. I'm not really sure for the reason of seperating them, but I assume that it is for interference reasons and that the TV should power up if given 13V to all of those points even if from the same source. I rescued a similar set. The three supplies are, in fact, separate (common return). I didn't bother to sort out "why" as the set I have came with the brick. But, the schematic shows them as separate. Some possible reasons: - keep the backlight supply isolated from the signal processing supply (keeps audio/video cleaner) - make sure the "processor" power supply comes up before other supplies - allow the processor to run even if the other supply(ies) die (so it can blink an error indicator) - etc. Anyhow I have tried powering it by tying all of the 13V+ togeather and giving them 13V and I get nothing except for a small noise from the speakers and a light very briefly turns on. Just enough to see it. I'm not sure I would have arbitrarily tied all of the supplies together. There might be some power sequencing issues that your "patch" could make problematic. Of course, its too late *now*... : Does anyone have any expirenence with this TV? I have a friend with the same tv.. Maybe I can borrow their AC adapter and try it on this one. That's the *first* thing I would have tried (realizing that you *could* possibly toast their brick in the process -- so hope it is an understanding friend! : ) Well I was wrong about my friends tv. It was a newer version which included the smps inside the case... Anyhow. I managed to find 3 different supplies around here and wired them all to the TV. It responded the same as before. A little noise from the audio amp and the power light briefly flashed once. I started probing around with the meter and can't see where this thing is using the voltages to combine to make a floating voltage. What I can see is they did use it to completely isolate the inverters from everything else. The ground for the inverter is seperate as well. On the main PCB they have 2 circuits that have their grounds tied togeather. I think one is feeding the tuner and one is feeding the audio amp. Anyway.. I guess its on to trouleshooting the main pcb. Mike |
#8
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Sharp Aquos LC20E1-S LCD TV Strange AC adapter
Michael Kennedy wrote:
Hi everyone.. I recently got a Sharp Aquos LC20E1-S LCD TV. The problem is it didn't come with a power brick. So go to Radio Shack and get a dick sucking faggot ass power brick, then. |
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