Need help for a 5.1 reciever

partyface86 · 24th August 2012, 12:13 PM

Hi everyone. I have just registerd to this forum hoping that someone can help me with a few tips. I don`t know if diyaudio.com is the right place for this but i`ll give it a try. A have just aquired an Onkyo TX-SV545 5.1 audio video reciever. It`s a pretty old model dating back to `99 but i kinda like it. My problem is that the reciever powers on, every switch every function works fine, the display is displaying everything that needs to be displayed but i have no sound. All of the 5 audio power stages are working perfectly, i have tested them with an externel audio signal. If i connect an audio source to any of the inputs except the 5.1 input, the rear speakers a working but at a very low volume. If i move te volume knob nothing happens only if it`s fully turned down then the sound stops, if i turn it up even just 1db the audio suddenly turns on like it`s a switch and no matter how far a turn it up the volume stayes the same. I now it`s not a diy amp, but the repair would be diy by me

I really would like to fix this amp beacuse it would be a nice upgrade from my Yamaha A-960

redrooster · 24th August 2012, 01:08 PM

If I was you I would check the boards for hairline cracks in case it has been dropped check for loose components,transistors ect... I use a toothbrush to poke around when its on, you can push down on the boards a bit while its on to check for cracks as well.Have a look at the ribbon connectors they can come loose.If it has the old style pots and switches(not digital) give them a clean and be sure to check for cold solder joints,If a solder joint doesn't look right resolder it by melting the joint and adding just a little bit more solder for the flux.Try that!

partyface86 · 24th August 2012, 01:47 PM

I have checked for cracks and bad solder joints and everything looks fine. A have pushed and poked the components and PCBs but nothing. It looks like that there is a probleme in the preamp stage, or some microcontroller. There are a lot of ICs, my guess would be that it has a major problem or something minor that just needs to be found. But what?

redrooster · 26th August 2012, 02:54 AM

I would check your ICs that they are getting correct power for a start,download their datasheets and look for the typical power that they run at and what pins to measure. You will need a service manual to tell you as well.Check for discolored resistors bulging leaking capacitors,blown transistors,diodes,zener diodes ect... Do you have a DMM (Digital Multimeter)My advice is if you don't have much experience at fixing amps you'll be better off dicing it and getting one that works,honestly.

partyface86 · 26th August 2012, 04:16 PM

I have measured some of the opamps and the are all getting power as they should, however i dod not measure the controller ICs. I have a service manual but most parts are unreadable, i found it on google in pdf but it`s of poor quality. There are two 12v voltage regulators both of them positive and they are getting pretty hot, but they work fine and i have seen perfectly working amps with regulators that worked with the same temperatures. I have some experience in electronics, specially amps, but most of the audio gear I have repaired were vintage, the only modern gear i have repaired was a Panasonic mini Hi-Fi system but that only had bad solder joints. Another thing that i`ve found is thet the inputs are acting weird. No matter to what input i connect there is always sound regardless of input selection but only for the rears and in the same way with no control over volume and tone correction.

24th August 2012, 12:13 PM	#1
partyface86 diyAudio Member Join Date: Aug 2012	Need help for a 5.1 reciever Hi everyone. I have just registerd to this forum hoping that someone can help me with a few tips. I don`t know if diyaudio.com is the right place for this but i`ll give it a try. A have just aquired an Onkyo TX-SV545 5.1 audio video reciever. It`s a pretty old model dating back to `99 but i kinda like it. My problem is that the reciever powers on, every switch every function works fine, the display is displaying everything that needs to be displayed but i have no sound. All of the 5 audio power stages are working perfectly, i have tested them with an externel audio signal. If i connect an audio source to any of the inputs except the 5.1 input, the rear speakers a working but at a very low volume. If i move te volume knob nothing happens only if it`s fully turned down then the sound stops, if i turn it up even just 1db the audio suddenly turns on like it`s a switch and no matter how far a turn it up the volume stayes the same. I now it`s not a diy amp, but the repair would be diy by me I really would like to fix this amp beacuse it would be a nice upgrade from my Yamaha A-960

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24th August 2012, 01:08 PM	#2
redrooster diyAudio Member Join Date: Jan 2009 Location: Geraldton Western Australia	If I was you I would check the boards for hairline cracks in case it has been dropped check for loose components,transistors ect... I use a toothbrush to poke around when its on, you can push down on the boards a bit while its on to check for cracks as well.Have a look at the ribbon connectors they can come loose.If it has the old style pots and switches(not digital) give them a clean and be sure to check for cold solder joints,If a solder joint doesn't look right resolder it by melting the joint and adding just a little bit more solder for the flux.Try that!

24th August 2012, 01:47 PM	#3
partyface86 diyAudio Member Join Date: Aug 2012	I have checked for cracks and bad solder joints and everything looks fine. A have pushed and poked the components and PCBs but nothing. It looks like that there is a probleme in the preamp stage, or some microcontroller. There are a lot of ICs, my guess would be that it has a major problem or something minor that just needs to be found. But what?

26th August 2012, 02:54 AM	#4
redrooster diyAudio Member Join Date: Jan 2009 Location: Geraldton Western Australia	I would check your ICs that they are getting correct power for a start,download their datasheets and look for the typical power that they run at and what pins to measure. You will need a service manual to tell you as well.Check for discolored resistors bulging leaking capacitors,blown transistors,diodes,zener diodes ect... Do you have a DMM (Digital Multimeter)My advice is if you don't have much experience at fixing amps you'll be better off dicing it and getting one that works,honestly.

26th August 2012, 04:16 PM	#5
partyface86 diyAudio Member Join Date: Aug 2012	I have measured some of the opamps and the are all getting power as they should, however i dod not measure the controller ICs. I have a service manual but most parts are unreadable, i found it on google in pdf but it`s of poor quality. There are two 12v voltage regulators both of them positive and they are getting pretty hot, but they work fine and i have seen perfectly working amps with regulators that worked with the same temperatures. I have some experience in electronics, specially amps, but most of the audio gear I have repaired were vintage, the only modern gear i have repaired was a Panasonic mini Hi-Fi system but that only had bad solder joints. Another thing that i`ve found is thet the inputs are acting weird. No matter to what input i connect there is always sound regardless of input selection but only for the rears and in the same way with no control over volume and tone correction.