Good evening everyone.
As the title states, I have a Sony STR-DA1200es receiver.
I am looking to service the AV amp, as it seems to be losing its mojo or power to drive somewhere. Doesn't seem to be effortless power to drive the speakers like before. I just find myself turning up the volume rather than addressing the situation.
Now as the effortless efficiency to drive the speakers and bass seems to be going downhill I am here.
I have just re biased all 7 amplifiers 😱 noted left channel was at 14mV when all were at 10mV (suggested 5-20mv).
Guessing due to the age of the AV amp 7 years, I should start looking at recapping the electrolytics.
This is where I need help as the Amp has maybe 7 separate PCB's . The only ones I need to concentrate on seem to be the PSU PCB, A Class Amp Board and Power Amp board.
Can anyone suggest the most likely one to tackle as I don't want to replace all caps, very costly.
I have the service manual should anyone wish to point me in the correct direction,
And this is my setup I have for diagnosing
I could ask for my lab guys at work for help, but they always seem to have the attitude of we are better than a tech.
Thanks in advance
As the title states, I have a Sony STR-DA1200es receiver.
I am looking to service the AV amp, as it seems to be losing its mojo or power to drive somewhere. Doesn't seem to be effortless power to drive the speakers like before. I just find myself turning up the volume rather than addressing the situation.
Now as the effortless efficiency to drive the speakers and bass seems to be going downhill I am here.
I have just re biased all 7 amplifiers 😱 noted left channel was at 14mV when all were at 10mV (suggested 5-20mv).
Guessing due to the age of the AV amp 7 years, I should start looking at recapping the electrolytics.
This is where I need help as the Amp has maybe 7 separate PCB's . The only ones I need to concentrate on seem to be the PSU PCB, A Class Amp Board and Power Amp board.
Can anyone suggest the most likely one to tackle as I don't want to replace all caps, very costly.
I have the service manual should anyone wish to point me in the correct direction,
And this is my setup I have for diagnosing
I could ask for my lab guys at work for help, but they always seem to have the attitude of we are better than a tech.
Thanks in advance
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It seems like you already have the gear and the background to find the mojo without needing outside help. 🙂
Anyway, 7 years is not old enough to consider cap. failure. Have you changed the location or furniture arrangement without running the speaker auto-calibration or perhaps the calibration has just reset to something useless without your notice?
Anyway, 7 years is not old enough to consider cap. failure. Have you changed the location or furniture arrangement without running the speaker auto-calibration or perhaps the calibration has just reset to something useless without your notice?
Already tried what you have mentioned.
I am wondering if it is the source that is causing the problem.
Do alot of listening to music online now and the adverts always seem louder (ie, youtube, then the source seems quiet)
I seem to have lost the bass in music, through all channels.
Knowing the average lifespan of a cap (around 10,000 hours) The amp is on for at least 8 hours per day since it was purchased, hence I am thinking caps are going leaky.
It is audible now, but somehow not the same unless I start pushing the volume.
Maybe I have some dry joints, but I am suspecting caps.
This is where I am hoping someone with more experience can jump in?
I am wondering if it is the source that is causing the problem.
Do alot of listening to music online now and the adverts always seem louder (ie, youtube, then the source seems quiet)
I seem to have lost the bass in music, through all channels.
Knowing the average lifespan of a cap (around 10,000 hours) The amp is on for at least 8 hours per day since it was purchased, hence I am thinking caps are going leaky.
It is audible now, but somehow not the same unless I start pushing the volume.
Maybe I have some dry joints, but I am suspecting caps.
This is where I am hoping someone with more experience can jump in?
I do have the equipment at work and the expertise in the lab. But I would hate to go down this route. I still consider myself as learning, rather than knowing all.
Don't work on audio day in day out only as a hobby, this is why I feel I need help on this one.
My primary work is on drivers and ballasts etc, eg, 200w led drivers. but my passion is audio and I lack the experience.
I plan on cleaning the pcb's and applying new thermal paste, but I dont think this will solve my problem.
I think my problem lies in the left channel working at 14mV opposed to the other 6 channels at 10mV, and I think the bias difference has took a strain elsewhere.
In summary I do have power available, but I have to crank the volume up. This is why I am suspecting dry joints or leaky caps.
Hoping someone can correct me at this point 🙂
Don't work on audio day in day out only as a hobby, this is why I feel I need help on this one.
My primary work is on drivers and ballasts etc, eg, 200w led drivers. but my passion is audio and I lack the experience.
I plan on cleaning the pcb's and applying new thermal paste, but I dont think this will solve my problem.
I think my problem lies in the left channel working at 14mV opposed to the other 6 channels at 10mV, and I think the bias difference has took a strain elsewhere.
In summary I do have power available, but I have to crank the volume up. This is why I am suspecting dry joints or leaky caps.
Hoping someone can correct me at this point 🙂
'Can't help with the quality of source material but surely you could use, borrow or beg a disc player and a similar HT amplifier and try known, conventional recordings as a standard of comparison for bass, dynamic range etc. Unless you keep referring to a standard for comparisons, all manner of purely subjective effects, even moods, listening fatigue and changing programme simply confuse your listening evaluations.
If anything kills music for me, its the massive amounts of compression now used on recordings generally and that additional amount for 'net distributions in particular.
With the amplifier, dry joints won't show up only in the way of diminished dynamics and frequency response etc. Not at least in the same way across all 7 channels unless other, more obvious faults like no or intermittent signal, odd noises, L/R differences etc are apparent too. As there are only 2 main smoothing caps for the power supplies of all 7 amplifiers, I guess it's obvious that C1401,2 on the main board will need testing for ESR first before replacing, to test your hypothesis.
If anything kills music for me, its the massive amounts of compression now used on recordings generally and that additional amount for 'net distributions in particular.
With the amplifier, dry joints won't show up only in the way of diminished dynamics and frequency response etc. Not at least in the same way across all 7 channels unless other, more obvious faults like no or intermittent signal, odd noises, L/R differences etc are apparent too. As there are only 2 main smoothing caps for the power supplies of all 7 amplifiers, I guess it's obvious that C1401,2 on the main board will need testing for ESR first before replacing, to test your hypothesis.
is the source mechanism moving freely lubed not dragging itself, an all of the sudden problem sound like a source problem, a cd laser mech. binding can cause a weak channel etc. .....
Hi, after rethinking today I doubt it could be dry joints as the problem would be constant and intermittent as stated. I am thinking leaky caps. But I will hook the speakers up to another output on the amp and try the source on a different input. If I have the same results, then this will leave me with the source as being the problem as I can't see the problem being across all 7 channels.
Really need to get a dedicated stereo amp. Always keep looking for musical fidelity x-a50s mono blocks but they seem to be rarer than hens teeth.
Although the clone pcbs look tempting, I'm unsure what the pcb quality would be like.
Really need to get a dedicated stereo amp. Always keep looking for musical fidelity x-a50s mono blocks but they seem to be rarer than hens teeth.
Although the clone pcbs look tempting, I'm unsure what the pcb quality would be like.
Ok, switched the input and speakers to a different output. No improvement.
Just had a quick listen to the radio on the amp, again output is down until I start cranking the volume.
I do have a spare small 50w denon power amp lying around so going to hook it up and use the pre outs of the receiver. Then compare my refernce song and see it this improves anything. The efficiency just doesn't seem to be there, it can't be my ears haha.
I know the amp and song well, have also had 3 previous amps the same, as I always found I go back to this amp after upgrading.
Oh well will try the power amp and report back.
Just had a quick listen to the radio on the amp, again output is down until I start cranking the volume.
I do have a spare small 50w denon power amp lying around so going to hook it up and use the pre outs of the receiver. Then compare my refernce song and see it this improves anything. The efficiency just doesn't seem to be there, it can't be my ears haha.
I know the amp and song well, have also had 3 previous amps the same, as I always found I go back to this amp after upgrading.
Oh well will try the power amp and report back.
Ok, progress is made.
Connected the spare power amp on to the pre outs of the sony (so the sony is still receiving the source then diverting to pre out) made no difference at all.
So just bypassed the Sony all together, pc output straight to power amp and controlling volume via pc. The mojo is back. I must add it is a very high end pc with a good soundcard.
I think by process of elimination I must be looking at a analog input fault on the Sony amp, as trying different inputs, different speaker outputs and the pre outs all made no difference. The only thing being left is surely the analog input PCB.
Does this sound viable?
Before I go start taking it apart (big job) to check reference voltages on buffers etc, or could the fault be elsewhere eg, PSU (but I suppose I would only know this by checking reference voltages on the analog input PCB).
Sorry it is not very DIY related atm, but if I could rectify the fault, maybe I can make some mods to the amp, maybe a first for diy receiver?
Connected the spare power amp on to the pre outs of the sony (so the sony is still receiving the source then diverting to pre out) made no difference at all.
So just bypassed the Sony all together, pc output straight to power amp and controlling volume via pc. The mojo is back. I must add it is a very high end pc with a good soundcard.
I think by process of elimination I must be looking at a analog input fault on the Sony amp, as trying different inputs, different speaker outputs and the pre outs all made no difference. The only thing being left is surely the analog input PCB.
Does this sound viable?
Before I go start taking it apart (big job) to check reference voltages on buffers etc, or could the fault be elsewhere eg, PSU (but I suppose I would only know this by checking reference voltages on the analog input PCB).
Sorry it is not very DIY related atm, but if I could rectify the fault, maybe I can make some mods to the amp, maybe a first for diy receiver?
I don't think this an analog circuit problem with the HT receiver. It is likely a programming difficulty since the stereo signal input gets reconverted to digital first before then being processed for multi-channel playback. Perhaps you could find out what the stereo output possibilities really are from the user manual.
Hi Ian, the amp is in 2ch stereo mode with no processing added. Same with the output from the computer everything is set for stereo.
Hi Mark. I just had a problem with my Sony that I got away with turning up the volume to correct for a while too. Might not be the same thing you are referring to though. Turned out to be the relays. They are not totally sealed and got corroded. Also an experienced tech told me that more times than not, the relays have ring cracks on the solder joints. You can look up my post on this forum about it about a week ago.
If it isn't that (my guess is it isn't), If an amp or preamp is lacking power, the first place I would look is the power supply. Check the voltages coming off of the supply and compare them to the repair manual. I wouldn't doubt you have some bad caps especially if your runs as hot as mine did.
Those are my initial thoughts anyway. Let me know how it turns out. I know how it feels to be without your receiver, you have to get your mojo back!
If it isn't that (my guess is it isn't), If an amp or preamp is lacking power, the first place I would look is the power supply. Check the voltages coming off of the supply and compare them to the repair manual. I wouldn't doubt you have some bad caps especially if your runs as hot as mine did.
Those are my initial thoughts anyway. Let me know how it turns out. I know how it feels to be without your receiver, you have to get your mojo back!
Hi Shredhead,
Thanks for the thumbup on the relays.
After messing around last night, I managed to get all analog inputs clipping and very quiet distorted sound (maybe I shorted an input by mistake) Couldn't get normal sound last night (but digital inputs worked).
Listening today and low and behold all is well again with the drive that I had been missing.
Quick look under the hood today and I can see some PCBs have distorted with heat and heating marks above them PCBs on the case top.
Think I need to strip it down and investigate and check voltages. Wouldn't surprise me if I have leaky caps somewhere, with the heat in the amp I wouldn't be surprised if it has shortened their life.
Thanks for the thumbup on the relays.
After messing around last night, I managed to get all analog inputs clipping and very quiet distorted sound (maybe I shorted an input by mistake) Couldn't get normal sound last night (but digital inputs worked).
Listening today and low and behold all is well again with the drive that I had been missing.
Quick look under the hood today and I can see some PCBs have distorted with heat and heating marks above them PCBs on the case top.
Think I need to strip it down and investigate and check voltages. Wouldn't surprise me if I have leaky caps somewhere, with the heat in the amp I wouldn't be surprised if it has shortened their life.
Hope my last post makes sense.
Can't understand why last night it was clipping and very very low output on all analog stages, with digital inputs working normal (like I said I probably shorted an input).
And now it seems to be working like it should have, back at my ref vol level of -30dB and all the mojo is back, Before I was taking it to -20dB and it still lacked bass.
No settings changed etc, only disconnected analog inputs.
Baffled is not the word 😱
Can't understand why last night it was clipping and very very low output on all analog stages, with digital inputs working normal (like I said I probably shorted an input).
And now it seems to be working like it should have, back at my ref vol level of -30dB and all the mojo is back, Before I was taking it to -20dB and it still lacked bass.
No settings changed etc, only disconnected analog inputs.
Baffled is not the word 😱
Mine sounded distorted and low in output too at times. Might still be those relays. You could try shorting the pins on them to check or open them up and mess around with them that way. If it's not, my money is on heat breaking down some component being the culprit, they should put fans in all of their receivers to prolong the life.
Your receiver is jammed with boards, I understand why you don't feel like ripping it all apart. Maybe your bottom comes off to make things more simple? Discoloration on the board due to heat makes me look for bad solder joints. You can try tapping on different parts while it is acting up to see if it comes back to life.
Receivers are a pain in the butthole but you have an awesome setup and know how already so I have faith that you will get it going again.
Your receiver is jammed with boards, I understand why you don't feel like ripping it all apart. Maybe your bottom comes off to make things more simple? Discoloration on the board due to heat makes me look for bad solder joints. You can try tapping on different parts while it is acting up to see if it comes back to life.
Receivers are a pain in the butthole but you have an awesome setup and know how already so I have faith that you will get it going again.
That is part of my work setup, home setup is a meter and soldering iron.
This amp is a big job to strip down, but I use it for stereo use at the moment until I can find some musical fidelity x-a50s.
All is working good on it now, that I am slightly reluctant to strip it. Most of my work involves SMD 0603 components and I know how hard it is looking for stressed/hairline cracks involving heat in my line of work. And the Amp uses a hell of alot more.
From shorting the analog inputs by accident while live,touching negative to positive. Something has changed that I can't quite work out. This just proves I was right in thinking analog input problem. Unless it can be a feedback problem (which I hate, going around in circles for ages and triggering everything).
This amp is a big job to strip down, but I use it for stereo use at the moment until I can find some musical fidelity x-a50s.
All is working good on it now, that I am slightly reluctant to strip it. Most of my work involves SMD 0603 components and I know how hard it is looking for stressed/hairline cracks involving heat in my line of work. And the Amp uses a hell of alot more.
From shorting the analog inputs by accident while live,touching negative to positive. Something has changed that I can't quite work out. This just proves I was right in thinking analog input problem. Unless it can be a feedback problem (which I hate, going around in circles for ages and triggering everything).
Maybe boring for some, but it is a 100% strip down job.
Analog input is distorted and clipping when compared to digital from the same source. Seems the same no matter what analog input, not massive distortion but enough for me to tell the difference from the amp not working correct.
Fairly confident the analog input board is at fault, will strip down tomorrow and see what is going on.
Not what I wanted, but oh well.......pics to follow
Analog input is distorted and clipping when compared to digital from the same source. Seems the same no matter what analog input, not massive distortion but enough for me to tell the difference from the amp not working correct.
Fairly confident the analog input board is at fault, will strip down tomorrow and see what is going on.
Not what I wanted, but oh well.......pics to follow
I'm not sure I understand you. If you hook something up to a tape or video monitor out for example... the analog ins are breaking up but not the digital ins? Do the op amp voltages seem correct? The sonys are known for solder joints cracking on the rca ins and outs while you're in there.
Hi Shred.
Nope 🙄
If I connect anything to any analog RCA input, the speaker output seems to lose its efficiency to drive (ie, lack of bass and quieter).
If I connect to a digital input everything is normal.
This is why I believe I have a fault on the analog board somewhere, seems as analog and digital both use the same bias, A Cass and Power PCBs. Analog and Digital input PCBs are separate.
Having started to strip it today and having a good look around, there are no dry joints or any bulging caps etc.
But looking at the design and seeing electrolytic caps mounted above heat sinks and next to them on the analog PCB, I think its safe to assume it will be a capacitor issue. All the caps are rated at 85c and have a lifespan of 2000 hours at this temp.
I can safely say this amp has around 10,000 hours use and the temps inside get quite hot.
Not going to start checking voltages until I get it in to work and on isolated mains and variac etc, not much room inside the chassis to move.
But I imgagine Vcc's to be fine, think it is caps coming to the end of there life.
As I don't work in audio, could leaky caps cause a lack of bass and drive? To me it seems possible.
Sorry for it being long, but I hope you now understand the problem I am having.
Currently pricing the cost of replacing all electrolytic caps in the analog, e-vol, A Class, Power amp and DC supply PCBs. Could get costly. But thankfully they all seem to be same value caps just lots with it being 7 channel amp.
It is a ES range amp and build quality etc is sublime and sound when it works, if I want an equivalent now I would be looking at three times what I originally paid for it.
Anyway I am ranting now, hope it seems more clear.
Nope 🙄
If I connect anything to any analog RCA input, the speaker output seems to lose its efficiency to drive (ie, lack of bass and quieter).
If I connect to a digital input everything is normal.
This is why I believe I have a fault on the analog board somewhere, seems as analog and digital both use the same bias, A Cass and Power PCBs. Analog and Digital input PCBs are separate.
Having started to strip it today and having a good look around, there are no dry joints or any bulging caps etc.
But looking at the design and seeing electrolytic caps mounted above heat sinks and next to them on the analog PCB, I think its safe to assume it will be a capacitor issue. All the caps are rated at 85c and have a lifespan of 2000 hours at this temp.
I can safely say this amp has around 10,000 hours use and the temps inside get quite hot.
Not going to start checking voltages until I get it in to work and on isolated mains and variac etc, not much room inside the chassis to move.
But I imgagine Vcc's to be fine, think it is caps coming to the end of there life.
As I don't work in audio, could leaky caps cause a lack of bass and drive? To me it seems possible.
Sorry for it being long, but I hope you now understand the problem I am having.
Currently pricing the cost of replacing all electrolytic caps in the analog, e-vol, A Class, Power amp and DC supply PCBs. Could get costly. But thankfully they all seem to be same value caps just lots with it being 7 channel amp.
It is a ES range amp and build quality etc is sublime and sound when it works, if I want an equivalent now I would be looking at three times what I originally paid for it.
Anyway I am ranting now, hope it seems more clear.
The only experience I have with caps going bad in an amp is: a plate amp I had went into dangerously wild oscillations because of bad caps on the power supply side of things. They went bad because of heat I know for sure though.
I know they can cause distortion as they lose their value in the audio side of things so I wouldn't doubt at all that they would be the culprit. Especially if your amp runs that hot. Time to start testing those suckers and see right?
I know they can cause distortion as they lose their value in the audio side of things so I wouldn't doubt at all that they would be the culprit. Especially if your amp runs that hot. Time to start testing those suckers and see right?
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