Marrantz SR3001: extended static followed by a pop when first turning on

StoleMyOwnCar

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I have had, for about 5-6 months now, a Marrantz SR3001 from Goodwill (for the curious, 26$). Whenever I turn it on, it has static coming out of (as far as I can tell) all channels. This lasts for about 1-2 minutes, followed by a single pop. Afterwards it continues to play just fine for however long I have it turned on. The static period might or might not be getting longer... or it might just be random. I haven't timed it, since I turn it to another digital input during the period to avoid having it potentially damage my speakers--the static still drains out even if not going through the speakers. The first few times it happened, though, the speakers seemed to be undamaged. They play just fine. I think (don't quite remember) the audio also plays in the background while the static happens.

The setup is PC+HDMI->TV+TOSLINK->Receiver+Speaker wire->2x DCM CX-17+Polk Center (also a sub but that's just line level output)

Guess just a few questions:
1. What could cause this? I'm thinking capacitor related since it seems to be power that didn't drain out and then is stuck there, maybe by a diode or something limiting flow to ground. But I'm no power electronics person.
2. Should I just leave it on instead of turning off after workout sessions? (this is a treadmill+PC 360 controller gaming room) I'm not sure how these types of issues respond and if it would be better to just leave the device on.
3. Any quick or easy fixes? Will this keep degrading if I leave it alone?

Pinging B00nie if they're still around this forum since they know this stuff.

Thanks
 
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Does the audible static frequency oscillate or stay the same frequency until it stops? Does it fit in the 60Hz range of power line transmission? There are phone apps for audible frequency spectrum analysis that are fairly accurate.
 
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t1337duder

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My Marantz SR5014 has static depending on what USB devices are plugged into the PC. Weird ground loop issue.
 

prime2515102

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Sounds like the section for the optical input may have gone bad (possibly a capacitor, a transistor, or an IC). Try a TOSLINK to coax convertor (these can be had for under $15) and try one of the two coax inputs, or if you have a CD/DVD/Blu-ray player with a coaxial output you could just try that.

Since you said you can silence it by switching to an unused digital input, I would rule out power supply, preamp, and output sections. Also, since the connection is optical, I would rule out grounding issues as there is no electrical connection at all and those make a fairly consistent hum or buzz anyway, not static and pops.
 

StoleMyOwnCar

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Oh, I wasn't sure how dead [H] was these days after Kyle left, so thought it'd take a day or two to get responses.

Does the audible static frequency oscillate or stay the same frequency until it stops? Does it fit in the 60Hz range of power line transmission? There are phone apps for audible frequency spectrum analysis that are fairly accurate.

From what I remember it literally just sounds like TV static, there's not a general tone to it. I'll try your suggestion and get an app for an FFT (which is what I guess you're wanting) when I can though, you got any suggestions for apps you trust? Using an iPhone FWIW.

My Marantz SR5014 has static depending on what USB devices are plugged into the PC. Weird ground loop issue.
Well this is much older than that, but I guess that's possible on the TOSLINK connection. That being said when I have had ground loop issues on motherboards connections, they didn't really go away after waiting some time, they just stayed around. (I remember finding some youtube vid where it cut the ground wire to a USB plug and that finally fixed the front output on one of my super old builds lol)

Sounds like the section for the optical input may have gone bad (possibly a capacitor, a transistor, or an IC). Try a TOSLINK to coax convertor (these can be had for under $15) and try one of the two coax inputs, or if you have a CD/DVD/Blu-ray player with a coaxial output you could just try that.

Since you said you can silence it by switching to an unused digital input, I would rule out power supply, preamp, and output sections. Also, since the connection is optical, I would rule out grounding issues as there is no electrical connection at all and those make a fairly consistent hum or buzz anyway, not static and pops.

Would the connection be relatively lossless? I guess it's just an exercise PC though, so not a huge deal. That isn't a huge price tag, but I'll see if I can find something with a coax output first, because it would kind of suck to buy it and have no results.

The thing is, I feel like I remember this static playing even when the radio output was on, too. It's just when I switch it to a disconnected digital input, it seems to just shut off all output to the speakers. But I'm not sure what stage it does that in. I'll have to do more testing, sorry, should have done more thorough testing before I made this topic.
 

prime2515102

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Would the connection be relatively lossless?
I don't believe it would have any effect on the sound quality, it's the same digital signal, just converted from optical to copper, which has much higher bandwidth and is able to be run much longer distances.
 
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Audio spectrum viewer @ 99 cents is the cheapest and it works well enough for your needs. Essentially just need to know what the frequency is to start looking into the different sections of the schematics on that unit. I also found a service manual for it on ebay for less than 20 dollars if your serious about fixing it. First step I would take is to disconnect all outputs and and listen very carefully for an audible but faint crackle sound of an overload disconnect relay experiencing contact bounce until it connects with the barely audible click.
 
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StoleMyOwnCar

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Audio spectrum viewer @ 99 cents is the cheapest and it works well enough for your needs. Essentially just need to know what the frequency is to start looking into the different sections of the schematics on that unit. I also found a service manual for it on ebay for less than 20 dollars if your serious about fixing it. First step I would take is to disconnect all outputs and and listen very carefully for an audible but faint crackle sound of an overload disconnect relay experiencing contact bounce until it connects with the barely audible click.

Thanks, I tried to do this earlier today but I didn't read the "disconnect all outputs" part so I didn't notice anything. At the very least all I heard at the time was just the amp turning on and then a click after it fully turned on. Had my ear up against it listening for anything, but all I heard was maybe a high pitched sound along with the amp hum. It was kind of like tinnitus. I kept hearing faint clicks but those were the amp kind of creaking under my head weight. I'll need to figure out a setup to actually test this with. Like I said the outputs do work while this is going on, they just have the static overlaid onto them. I'll try to test it tomorrow with everything disconnected and try to figure out some setup whereby I can listen without causing the device to creak under my massive ego.

StoleMyOwnCar Kyle is still around. He posts quite a bit and moderates the Soapbox section of the website.

I see. I don't have access to that part I think.
 
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Well an oscilloscope and a function generator are the best to test these things but those tools are not usually things most people have just lying around. Public libraries sometimes have schematics that you can make copies from for a small fee. Do you know any electronics techs that you could persuade to help you? Since you didn't disconnect the outputs did the static subside when you heard the relay click or does it continue afterward?
 
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StoleMyOwnCar

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Well an oscilloscope and a function generator are the best to test these things but those tools are not usually things most people have just lying around. Public libraries sometimes have schematics that you can make copies from for a small fee. Do you know any electronics techs that you could persuade to help you? Since you didn't disconnect the outputs did the static subside when you heard the relay click or does it continue afterward?
I think I didn't state this well but, the click that I heard was shortly after I turned it on. It's that normal click you hear right before the amplifier actually starts outputting sound. It was very audible (to me). And the thing is, the input sound does play while the static sound is going on, and after the click. It's just that the static is overlaid on top of it. The click only takes about several seconds at most to happen, and there's not really anything that I would call a "crackle" before it does. Just normal buzzing as the amp is engaging.

I thought you were talking about a separate click that was much harder to hear, because I always heard that first click very audibly on all of my amplifiers.

Sounds like the section for the optical input may have gone bad (possibly a capacitor, a transistor, or an IC).
Hence since I realized that the static is overlaid on top of the audio (whether it's an analog input, radio, or said TOSLINK input)... I'm not sure if using a different type of optical able would help. Very awkward. The reason that nothing plays when I switch to another optical input is that it seems to just have a total shutoff to the amp section if it detects a digital input doesn't have any signal. What's odd is that the static drains out even when nothing is making it to the speakers...


Now, I have used an oscilloscope and function generator as part of my labs throughout my computer engineering courses, but I simply didn't care for analog circuits much. So I really don't trust myself around power circuits like this, which (as I understand it) could potentially kill me even while they are turned off, should I touch the wrong thing. I'm clumsy, a bad combination when paired with high voltage circuitry.

Anyway next I'll try taking that audio spectrum viewer app and doing some frequency analysis on the static out of the speakers. I'll try turning it down so I can capture the entire time until the pop and give you what comes out. hopefully my microphone will be good enough.

Thanks a lot for the help so far, guys/gals. I really like this amplifier so hopefully it won't degrade or something...
 

prime2515102

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One more question to narrow things down. Does this static sound come through headphones as well?
 
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Thats a good question as that could narrow it down by several amp stages depending upon design. After a bit of pokin around on the web it seems the marantz amps have had IC ,electrolytic caps and bad solder joints somewhat regularly. Unplug it and remove the cover and do a visual inspection for bleeding caps discoloration of the circuit board and over all soldered components for poor connections. Look for abnormally shiny or oxidized/discolored solder blobs.
 

B00nie

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Sounds like the filtering caps are gone. Probably they first fail to charge and then pop into action after warming up a bit.
 

StoleMyOwnCar

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One more question to narrow things down. Does this static sound come through headphones as well?

Yep, just tested it.

learners permit

So I did a spectrum analysis using a free app.


I did it right after I unplugged the headphones that I plugged in to test it. Unfortunately I did not get to the popping sound because I was starting to smell some burning and started to get worried. So towards the end you see the sound suddenly stop, that's because I pulled my phone away. This is odd, I've never really smelled burning from the amp before. I didn't see any smoke or anything, just smelled something burning. I turned it off and on again and then the static still died down after a bit and it is now working... very odd. I'm not sure if trying to make the amp switch over to the headphones when it started up triggered this behavior, or if it's just because I left the speakers on where instead I usually switch to an unused digital input.

Odd. I also did leave the heat off so it was a little colder while it was turned off (~60-66F as compared to the 69-70F I usually have it at). Not sure if that's related because B00nie said the filtering caps were gone and needed to warm up.

The microphone also does unfortunately have a sizeable noise floor, with a decent amount of frequency when in a relatively quiet room. I can give you a reading of that as well so that it's easier to compare.

Thats a good question as that could narrow it down by several amp stages depending upon design. After a bit of pokin around on the web it seems the marantz amps have had IC ,electrolytic caps and bad solder joints somewhat regularly. Unplug it and remove the cover and do a visual inspection for bleeding caps discoloration of the circuit board and over all soldered components for poor connections. Look for abnormally shiny or oxidized/discolored solder blobs.

What should I be careful of when doing this? Should I find some thick rubber gloves at the home depot first? Safety is the thing I'm most worried about here. If I can be safe doing it, I don't mind grabbing my camera and snapping some nice pictures of the entire thing, though.
 
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No just unplug it for an hour before so all the caps drain and np. Smell of burning indicates imminent fail so sooner is better. It also means there will be evidence of solder near melting point so look for the shiniest solder blobs they'll likely stand out from the rest. BTW your spectrum indicates that it's likely a faulty connection or component in one of the amp stages. The fact that it stops when warmer also points to faulty solder joint but transistors also have a tremendous response to temp changes so still a possibility. Temp increases the beta of transistors and drives them to saturation level at which all their design engineering goes flying out the window. Just do the visual and post some pics of suspect looking areas.
 
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StoleMyOwnCar

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No just unplug it for an hour before so all the caps drain and np. Smell of burning indicates imminent fail so sooner is better. It also means there will be evidence of solder near melting point so look for the shiniest solder blobs they'll likely stand out from the rest. BTW your spectrum indicates that it's likely a faulty connection or component in one of the amp stages. The fact that it stops when warmer also points to faulty solder joint but transistors also have a tremendous response to temp changes so still a possibility. Temp increases the beta of transistors and drives them to saturation level at which all their design engineering goes flying out the window. Just do the visual and post some pics of suspect looking areas.

Well it worked fine for hours after I turned it back on. The burning smell gradually went away. Weird.

Anyway, I took a decent amount of pictures of the inside with my camera.


Unfortunately I didn't really know what I was looking for. Let me know if there's any area you want me to zoom in on or something. I will say that the burning smell in general seemed to come from the upper left side mostly, that's where the large box is and where the power cord comes in.
 

B00nie

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Hmm.. if you don't even know what a transformer is, you probably shouldn't be messing inside that amplifier and leave it to a professional.

While you still breathe that is.
 

StoleMyOwnCar

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Hmm.. if you don't even know what a transformer is, you probably shouldn't be messing inside that amplifier and leave it to a professional.

While you still breathe that is.

I thought I made it pretty clear that I didn't have much intention of servicing it myself. The whole point of this is to find out what the issue is and how critical it is. If it's just going to stay a minor annoyance such as "well it'll take a minute or two before you can actually use it," then that's totally fine. If it's eventually going to catch on fire... well that's kind of not fine and I might take it to a specialist to fix. While I was taking these pictures, I made sure to still wear some protective equipment and didn't touch anything even though it was unplugged and powered down.

Most of these circuit elements I only remember from circuit diagrams or much smaller versions that aren't special made for these types of applications. Transformers in particular I don't think we ever actually used in our lab classes because we were mostly building low power circuits (and most of those were DC, or we used a function generator to make a low voltage AC current and measured various output and filtering characteristics). I mostly only saw them in diagrams. So yeah I know full well I'm out of my element, here. You don't need to warn me.
 

B00nie

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I thought I made it pretty clear that I didn't have much intention of servicing it myself. The whole point of this is to find out what the issue is and how critical it is. If it's just going to stay a minor annoyance such as "well it'll take a minute or two before you can actually use it," then that's totally fine. If it's eventually going to catch on fire... well that's kind of not fine and I might take it to a specialist to fix. While I was taking these pictures, I made sure to still wear some protective equipment and didn't touch anything even though it was unplugged and powered down.

Most of these circuit elements I only remember from circuit diagrams or much smaller versions that aren't special made for these types of applications. Transformers in particular I don't think we ever actually used in our lab classes because we were mostly building low power circuits (and most of those were DC, or we used a function generator to make a low voltage AC current and measured various output and filtering characteristics). I mostly only saw them in diagrams. So yeah I know full well I'm out of my element, here. You don't need to warn me.
You're free to do what you want. Just be aware that once you open the chassis, grabbing one wrong part of the amp can lead to a cardiac arrest. Just one wrong touch. The danger is mainly around the 'big box' in the case of an audio amplifier, unless you feed it with high volume music while checking it :D

Most people probably don't realize that a high power amp can put out 100 volts of signal also from the speaker outputs. 40+ can already kill you.
 
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StoleMyOwnCar

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You're free to do what you want. Just be aware that once you open the chassis, grabbing one wrong part of the amp can lead to a cardiac arrest. Just one wrong touch. The danger is mainly around the 'big box' in the case of an audio amplifier, unless you feed it with high volume music while checking it :D

Most people probably don't realize that a high power amp can put out 100 volts of signal also from the speaker outputs. 40+ can already kill you.

Well, that would depend on wattage, I think? I forgot what the resistance of the human body was calculated as but it changed depending on whether wet or dry, and it was the current that killed you, not the voltage...? That being said, again, I have no doubts that it's dangerous to go tinkering around in there when I haven't had more power electronics under my belt. But the thing was powered down and I had gloves on, and I wasn't even touching anything. Moreover I waited a full 24+ hours after powering it down (and by "powering down" I mean unplugging entirely). Is it still dangerous even then? I don't plan to open it when it's plugged in...

Do I need an app from imgur to view the pics? All I get is a blank screen when I try to view them.

You shouldn't. Here is a direct link to it.

And in case it's the preview messing things up, I put it in a code block.
Code:
https://imgur.com/a/JTX1AdS
 
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B00nie

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Well, that would depend on wattage, I think? I forgot what the resistance of the human body was calculated as but it changed depending on whether wet or dry, and it was the current that killed you, not the voltage...? That being said, again, I have no doubts that it's dangerous to go tinkering around in there when I haven't had more power electronics under my belt. But the thing was powered down and I had gloves on, and I wasn't even touching anything. Moreover I waited a full 24+ hours after powering it down (and by "powering down" I mean unplugging entirely). Is it still dangerous even then? I don't plan to open it when it's plugged in...
If you refer to the speaker outputs, yes. However on the transformer side there's a constant high current 110V (or 240V if in Europe) exposed, that's where the danger is. Also if the power supply has large filter caps like amps often do, the system may have residual voltage for minutes to hours after it's unplugged. So even when the cord is off, you can still shock yourself by accident. It only takes a few milliamps of current if/when the path of least resistance goes through the heart.

Old CRT tv's were notorious in this aspect as they had a voltage multiplier circuit producing 1-2 kilovolts to the CRT grid. That could zap you very nasty long after the cord is off.
 

StoleMyOwnCar

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If you refer to the speaker outputs, yes. However on the transformer side there's a constant high current 110V (or 240V if in Europe) exposed, that's where the danger is. Also if the power supply has large filter caps like amps often do, the system may have residual voltage for minutes to hours after it's unplugged. So even when the cord is off, you can still shock yourself by accident. It only takes a few milliamps of current if/when the path of least resistance goes through the heart.

Old CRT tv's were notorious in this aspect as they had a voltage multiplier circuit producing 1-2 kilovolts to the CRT grid. That could zap you very nasty long after the cord is off.

Well like I said, I waited 24 hours (probably more actually) before opening the thing up, and I had gloves on and then only took pictures with my camera... so... I think I followed enough safety precautions? I don't plan on trying to repair this myself, but I do need to just know if there's an issue that's going to degrade quickly since I use my exercise room very frequently.
 

atarione

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i mean... if you are going to have to pay a tech to fix this.. it is going to probably cost more than this thing is worth? they seem to be $199~ amp on ebay.. it looks "nice" but not OMG that is great... If you find a tech I bet it would be at least $200 to have them sort this one out...

I wouldn't be jazzed myself to keep using it since it is obviously malfunctioning.. I'd be afraid of burning the house down? I won't leave any of my vintage stuff on when I'm not actively using it /can keep an eye on it...

If this was my amp and my problem... I'd start looking around on let go / CL / Facebook Market place..etc (thrift stores) for a different amp... I do not think I would sink any money into what is essentially an obsolete (no offense) AV receiver?
 
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The caps on that amp have enough leakage that drains in less than an hour. Now a CRT display can bite for nearly a day because of the flyback potential is sooo high. Found that out the hard way. Those pics are not gonna help much and that unit has a ton of analogue filter circuits for low, high ,and band pass. Without a schematic an Oscope and access to the unit I can't help much more than the advice already given. I would advise that you give it a thorough dusting with an air compressor air wand and see if that helps. I've seen dust bridge circuits to the point of overload shutdown before especially when the relative humidity is high.
 

StoleMyOwnCar

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Issue with voltage is the higher it is, the farther it can zap you from. It only takes a few mA to kill if it crosses the right spot, regardless of voltage.

Edit: as little as 200mA, https://www.asc.ohio-state.edu/physics/p616/safety/fatal_current.html
I mean... I kind of doubt that a commercial amplifier that's been powered down for over 24 hours would have enough voltage left in it to arc and kill me. And in fact it didn't. But fair enough.

i mean... if you are going to have to pay a tech to fix this.. it is going to probably cost more than this thing is worth? they seem to be $199~ amp on ebay.. it looks "nice" but not OMG that is great... If you find a tech I bet it would be at least $200 to have them sort this one out...

I wouldn't be jazzed myself to keep using it since it is obviously malfunctioning.. I'd be afraid of burning the house down? I won't leave any of my vintage stuff on when I'm not actively using it /can keep an eye on it...

If this was my amp and my problem... I'd start looking around on let go / CL / Facebook Market place..etc (thrift stores) for a different amp... I do not think I would sink any money into what is essentially an obsolete (no offense) AV receiver?

That's probably true. Which I guess means that the main point of this was trying to figure out just how dangerous it was. In the meantime I guess I'll try to get a metal pan or something for it to rest on so that if it does burn it doesn't spread much. I already have a fire extinguisher in the room (no, not for this... I don't actually know why it's in there...).

The caps on that amp have enough leakage that drains in less than an hour. Now a CRT display can bite for nearly a day because of the flyback potential is sooo high. Found that out the hard way. Those pics are not gonna help much and that unit has a ton of analogue filter circuits for low, high ,and band pass. Without a schematic an Oscope and access to the unit I can't help much more than the advice already given. I would advise that you give it a thorough dusting with an air compressor air wand and see if that helps. I've seen dust bridge circuits to the point of overload shutdown before especially when the relative humidity is high.

Fair enough it does have a lot of dust. I'll give it a whirl. Thanks for at least giving it a shot.
 

Nobu

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I mean... I kind of doubt that a commercial amplifier that's been powered down for over 24 hours would have enough voltage left in it to arc and kill me. And in fact it didn't. But fair enough.

Sure, just pointing out that electrical safety is important regardless of voltage, but at high voltages you do have to be more careful because you can be zapped from farther away.

Was directed more at B00nie than you, I think. Not sure why I decided not to quote or mention the person I was responding to. :/
 

B00nie

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Sure, just pointing out that electrical safety is important regardless of voltage, but at high voltages you do have to be more careful because you can be zapped from farther away.

Was directed more at B00nie than you, I think. Not sure why I decided not to quote or mention the person I was responding to. :/
The natural resistance of the skin makes low voltages safe to handle. Wet hands lower the treshold considerably but still a 12-24V voltage is safe to touch with bare hands. Then again 24000 volts jumps across the air and can kill you yards away. I'm used to high voltages since I'm using 4000 volt bias in my DIY electrostatics and the step-up transformer multiplies the amplifier voltage up to 7000 volts. That's why it's a VERY bad idea to touch an uninsulated electrostat while it's playing music.
 
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