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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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Panasonic sa-ak25
I have this piece of.... on my bench for a few days now, its problem
is the sound is not loud enough, you have to put it to max to hear something. My co worker is convinced its not the output ic because the sound is not distorted, i re-did solders everywhere, still with the same problem. someone please help. Thanks Shane. |
#2
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Panasonic sa-ak25
On Feb 6, 9:30*am, wrote:
I have this piece of.... on my bench for a few days now, its problem is the sound is not loud enough, you have to put it to max to hear something. My co worker is convinced its not the output ic because the sound is not distorted, i re-did solders everywhere, still with the same problem. someone please help. Thanks Shane. Did you try a different loudspeaker???? |
#3
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Panasonic sa-ak25
Two pieces of information are needed. At least one would help, but
both would be better. Is the sound low when you use the AV jacks ? Does the TV have an indication when it is recieving a stereo broadcast ? Is it indicating a stereo signal ? On a Panasonic it might not, but if you have a channel you know has SAP, you can try to switch to that. If it reads the SAP the level coming out of the IF strip is sufficient, and if that is the case I'd say you have an 80% chance that the AV jacks will have low sound as well. In that case, if you lack a print, download the datasheet for the audio output IC. Find out just where volume control is achieved. This is all assuming this TV is stereo, if it is not, say so because then there is an entire different direction to take. JURB |
#4
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Panasonic sa-ak25
wrote in message ... Two pieces of information are needed. At least one would help, but both would be better. Is the sound low when you use the AV jacks ? Does the TV have an indication when it is recieving a stereo broadcast ? Is it indicating a stereo signal ? On a Panasonic it might not, but if you have a channel you know has SAP, you can try to switch to that. If it reads the SAP the level coming out of the IF strip is sufficient, and if that is the case I'd say you have an 80% chance that the AV jacks will have low sound as well. In that case, if you lack a print, download the datasheet for the audio output IC. Find out just where volume control is achieved. This is all assuming this TV is stereo, if it is not, say so because then there is an entire different direction to take. JURB I think you'll find that this "TV", is actually a hi-fi ... To the OP. I guess you have got the speakers in the right set of jacks and the right way round ? With their red / black / blue / grey terminals, it's easy to get the connections confused on one of these, if you're not using its original speakers with the matching 4 coloured wires. Use the blue (-) and grey (+) terminals if you are testing with 'normal' 2 wire speakers. The unit is also mutable from the handset only, so if it has been muted, and you don't have the handset, then it might still be in that condition. I really can't remember if it de-mutes after a full power down, or if the volume is adjusted. Might be worth a look though. The RSN series output hybrid used on these is not the most reliable, but they are expensive, so if you do get to suspecting it, be pretty sure first ... Note that headphone switching is carried out at the RSN, pin 8, which should be at 0v. CP503 pin 12 is where it comes in. Might be worth checking that there is nothing amiss with either the headphone socket, or its solder joints, as I seem to recall that it pulls that line to pin 8 down via a grounding switch built into it. If that switch or a solder joint on it goes bad, the line is pulled up to rail, and the unit mutes. If you get to needing the schematics for this part of the circuit, mail me direct off-group, and I'll see what I can do for you. Arfa |
#5
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Panasonic sa-ak25
On Feb 7, 4:35*am, "Arfa Daily" wrote:
wrote in message ... Two pieces of information are needed. At least one would help, but both would be better. Is the sound low when you use the AV jacks ? Does the TV have an indication when it is recieving a stereo broadcast ? Is it indicating a stereo signal ? On a Panasonic it might not, but if you have a channel you know has SAP, you can try to switch to that. If it reads the SAP the level coming out of the IF strip is sufficient, and if that is the case I'd say you have an 80% chance that the AV jacks will have low sound as well. In that case, if you lack a print, download the datasheet for the audio output IC. Find out just where volume control is achieved. This is all assuming this TV is stereo, if it is not, say so because then there is an entire different direction to take. JURB I think you'll find that this "TV", is actually a hi-fi ... To the OP. I guess you have got the speakers in the right set of jacks and the right way round ? With their red / black / blue / grey terminals, it's easy to get the connections confused on one of these, if you're not using its original speakers with the matching 4 coloured wires. Use the blue (-) and grey (+) terminals if you are testing with 'normal' 2 wire speakers. The unit is also mutable from the handset only, so if it has been muted, and you don't have the handset, then it might still be in that condition. I really can't remember if it de-mutes after a full power down, or if the volume is adjusted. Might be worth a look though. The RSN series output hybrid used on these is not the most reliable, but they are expensive, so if you do get to suspecting it, be pretty sure first ... Note that headphone switching is carried out at the RSN, pin 8, which should be at 0v. CP503 pin 12 is where it comes in. Might be worth checking that there is nothing amiss with either the headphone socket, or its solder joints, as I seem to recall that it pulls that line to pin 8 down via a grounding switch built into it. If that switch or a solder joint on it goes bad, the line is pulled up to rail, and the unit mutes. If you get to needing the schematics for this part of the circuit, mail me direct off-group, and I'll see what I can do for you. Arfa- Hide quoted text - - Show quoted text - thanks a lot for your input guys. that was one thing we checked was the headphone jack, we've seen that problem before, where the micro thinks theres a jack plugged in so it cuts the sound to the speakers. but no it wasn't that. There's another control ic that was muting the sound, but not completely, it was like a half mute. anyways the headache is over. This was my first post, seems to work nicely thanks again, ill be sure to stick around Shane. |
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