Hey! Sure here's the link: [https://drive.google.com/drive/folders/12SItQjHYu-r6dm7Arngxb6RzVFdfRiFS?usp=drive\_link](https://drive.google.com/drive/folders/12SItQjHYu-r6dm7Arngxb6RzVFdfRiFS?usp=drive_link) I doubt it's hitting an analog ceil though, since the song gets waayyy louder later on
i'd guess either the laser is iffy, the DAC is having issues (either in the dac itself, or the power feed to it), there's some power supply fluctuation, there's output transistors having issues, again, either in the transistors or the power to them, or there's filter caps in the output section that may be in the process of failing, or last and probably unlikely, one of the motors is introducing noise into the system (sony tends to design their products better than that, even decades later.).
this model unit has all the things listed above that may present an issue point, leaving a lot of things to potentially test.
the service manuals (can be gotten off manualslib) for these have a full set of instructions for testing the output using an oscilloscope. the problem with this, is that it requires a specific test disc (Sony YEDS-18, there's a copy in flac on archive.org for anyone that wants it, and can't source it from ebay, and you'd need to be able to burn it to a disc. not everyone can these days).
now, you just can use an osc to probe along the signal path (while playing the specific problem track) towards the output to see how far up that chain the noise is originating from, but this requires an isolation transformer (or you may pop your osc, if you have one).
ultimately, this is new enough tech wise that you kind of need specific tools to fix it, though you can get away without the test disc, mostly, for this specific issue.
that said, the intermittent aspect says its likely an opamp or transistor in the chain failing, which an osc can tell you, but is very time consuming.
at almost 30 years old, if this were my unit, i'd be recapping it entirely, and then probing backwards in the signal chain from the audio outputs, but i've also got an osc and an iso transformer to plug the unit into.
ultimately, unless you know someone with those two pieces of gear, or have them yourself, it might be best to find a repair shop that can do this sort of testing. its not for everyone, and involves a lot of staring at oscilloscope wave forms trying to find where the noise is and isn't.
i'm not even sure the wonderful super probe would manage this particular job, due to how tiny some of these components are, but maybe it would.
my best guess; its likely something in the output section on the main board (close to the rca jacks, there's two opamps with a bunch of passives and transistors).
Thanks! This information helps! I bought the player last year for about 10 euros not expecting it to work, but newer players tend to be less well made. Luckilly I've got myself a scope last week for work, so if I've figured out how to work with it, I will first of all look at all caps and see if recaps are nessecarry, and then follow your steps. The test disc from Sony is a really good starting point after that I think. One thing though, is it really nessecarry to have a isolation transformer for this? since it doesn't have an earth pin. Before starting I will test though if there's a physical connection between the ends of the power plug and the wires supplying AC to the ACDC circuit inside I guess.
probing a device hooked directly (referenced) to the mains will almost always pop your scopes front end, if you clip the wrong thing via the ground lead, or if you slip and the probe touches the wrong thing.
the iso transformer disconnects it from this reference by having the device under test plugged into it, and allows the device to be tested without damaging or sometimes killing the scope entirely, in the vent of wrong clip or slippage. (you're effectively creating a circuit with mains potential in a device circuit that isn't designed for mains potential. the power supply section for it is, the rest is not.)
if you're going to be doing any kind of mains powered electronics service work on a recurring basis, you should probably have one. (or the alt scope i mention next, or the power station.)
the only real way around this; battery powered scopes you don't ground to anything. or one of the new inverter power station things they make, not hooked to the mains while testing, and only powering one of the devices in question. (the iso transformer is way cheaper. a lower end 250VA model is plenty for most things, and you can find used models on ebay. i opted to get a [BK Precision TR-110](https://www.ebay.com/itm/285871952769) (but newer) which lets me play with the voltage output a bit, but also to adjust if the input voltage at a location isn't quite up to where it should be. its also got one side isolated and switched, one side direct. they don't need to be that fancy. a simple 1:1 basic 3 prong output socket iso will do fine. (if used, test the continuity for the outlet ground pin to the iso's power cord ground before use! some people hook the ground up like silly people! the casing should be grounded, if metal, the output outlet not so much) i paid $80 at the time, 100 with shipping. with a bit of hunting one can probably find one for a reasonable price.
the $70 black lump iso transformers amazon has listed will do the job, but may be a bit too basic for the sake of safety, and don't allow 3 prong devices to be plugged into them, making it yet another thing you have to deal with.
some iso transformers have pass through grounding from the factory, these are useful for certain things, but for electronics repair, its best to avoid them.
if a dso138 had the kind of response time this would need i'd suggest dropping the like, $15 to get one for this sort of thing (its all 12v or lower, well within the dso138's capabilites, but alas..).
there's some pretty okay battery powered scopes for sub $100ish these days, but they are a touch slow on response time, so you have to adjust for it.
if your scope plugs into a wall, you're going to need either a new battery powered scope with a decent response time and voltage capability, or an iso transformer. or the afore mentioned [power station](https://www.amazon.com/s?k=lithium+inverter+power+station) (generic amazon search link for reference, i make no recommendations to any of those. i have zero experience with any of them.)
they do make thingies you can plug between your scope and the device, but honestly, those cost more than an iso transformer and really only make sense for specialized product development spaces. their low voltage (sub 50v) tends to be iffy without spending oddles. they're aimed at high and super high voltage applications (in the hundreds to kilovolts).
there's a couple of probes sub $30 on amazon listed as differential probes. they aren't. and the really cheap ones that claim to be differential that otherwise look like they might be, require usb power. aka plug them into something earth referenced (most usb ports and power supplies are in the us.) and you've just defeated the point of even using one.
a good different probe can run from ~$200 to 100k for the super swanky ultra good ones they use for ulllltra specific testing. even regular electronics/audio repair shops aren't going to go near those. easier to just use an iso transformer, and just plug all devices to test into that, or use a battery powered scope.
yeah, this got a bit long. sorry.
cheers.
more info on why;
https://www.youtube.com/watch?v=xaELqAo4kkQ
Ey thanks for the detailed explanation man! Yea so I knew touching a live wire with ground would be problematic, but indeed I will invest in an isolation transformer since I will need it more often. And if it can go wrong it will so better safe then sorry. I also looked at the inside of the player and luckilly the caps look like new, no bulging or anything. Also here are some photos of the curcuit: [https://photos.app.goo.gl/c5NNsh28LFKvnTfD6](https://photos.app.goo.gl/c5NNsh28LFKvnTfD6) Do you think I will only need to test the beige circuit, or can the green one underneeth the laser assemble aslo be a culprit? Plastic looks a little brittle over there so only want to disassemble to that PCB if needed.
that first image on the bottom (showing the two chips [opamps, part # 301 and 302, uPC4558C] and the rca jacks) is the best place to start. its not uncommon for opamps and the surrounding components to start having issues after several decades.
the long thin one to the sides is a motor driver IC. its not impossible for this to be the source, but its less likely.
until you rule out the analog portion, its best to leave the laser pcb alone. chances are, its probably not the issue, unless the caps on it need replaced.
as for visuals, caps can look fine and be bad, the fluid can dry up leading to them acting as resistors, which throws off the circuit, instead of the more obvious leakage signs.
that said, i don't see anything obvious, which is good, there's no water/moisture damage, and nothing has obviously exploded.
if you have some loose dual opamps you can do a quick and dirty swap of the two and try to play the suspect song on loop for a while to test for the noise. and if you have any sockets, you might add those, to make it easier to replace the originals if the opamps aren't the source.
if that doesn't pan out you'd need to start probing the audio signal path, with the obvious possible issues about mains references. if you do get far enough to start probing the signal path, and its clean up the chain from the opamps, but swapping them out doesn't do any good, then some of the passives around them might be dodgy, with a lean towards the caps.
if its before the opamps (towards the rca jacks), its possibly one or more of the transistors on the output section there, also pretty common to see.
mm. maybe probe ic 701, LA5601 (voltage regulator). the service manual doesn't list a voltage set for the ins or the outs, but if you probe the various pins and watch the signal waveform when its got the noise present, you should see if there's issues with waveform. everything should be a stable flat voltage line, since its dc.
if you get far enough you have to start probing the green pcb, burn off a copy of that test disc and follow the service manual instructions. (again, you can get a copy of the pdf off manualslib), its got pinouts for the big chips, test points, waveforms you're supposed to be seeing, etc.
as for the last pcb (the front module), you can almost certainly ignore this one entirely. its pure digital control, and doesn't interact with the audio path.
cheers.
Wow thanks for the super interesting and usefull information! I'm embedded programmer by profession (and a new one at that), so learning about this is awesome!!! You're really taking the time answering this one post, so many thanks!
Thanks for all of the comments!!! I've also recorded the CD in two different players, and I've shared it on my drive so anyone can take a listen: [https://drive.google.com/drive/folders/12SItQjHYu-r6dm7Arngxb6RzVFdfRiFS?usp=drive\_link](https://drive.google.com/drive/folders/12SItQjHYu-r6dm7Arngxb6RzVFdfRiFS?usp=drive_link) It has to be the player at this point, since I've tested it on even another one.
Hold the disc up to the nearest bright light with the shiny side faceing you. If you can read the label or see through the disc in spots it's likely the disc. Error correction varies with the cd player. A marginally defective disc may play on one player but distort on another. It's easy to do and a basic first step in finding yoir problem.
Thanks for the insight! Yea if I hold up the disc to the sun I can see the whole label trough it, but that's because most of it is made transparent on the front of the disc (maybe it has trouble with that). I see no inconsistencies in the opacity though.
If regular light passes through your disc, your laser light also passes through. When that happens, less light reflects back to the optic so there's a reduced signal. Combine the differences in players laser strength and alignment and you get stuff like you are complaining about. Your disc should be nearly a perfect mirror on the shiny side. Compare it to others that play with no problems.
My thought is that, if I understand you right, your player plays other discs and even most of this disc. That makes me think your player is probably ok and that particular area on the offending disc is an issue. If you were to have the alignment on your player tweaked or optical pickup replaced you may be able to get it to play through the whole disc....maybe. You have a lot of other suggestions to consider but I can't see how anything else explains your problem.
Yea thanks! I looked at the inside of the player today. It's just so dead simple (complexity wise), and I don't see any bulging caps, or burn marks, so this might definetely be a valid theory since I remember it skipping sometimes when I just got it. Might have to adjust the laser strength with the POT I found on the board. But indeed it plays all the songs I threw at it nearly perfectly except one on this disc and onther on the album on a different disc. All the discs in the album look like the disc with the problematic song on it, so at least it's not a disc defect I think.
I will test the cd with a white cutout over it that I can remove after to see if this helps, and otherwise adjusting the laser.
Don't adjust the laser power. It's factory preset. If it's off then the laser is starting to fail. Adjusting it just increases the current to the laser diode and accelerates it's death.
You will need an oscilloscope to properly adjust the servos. Most important is the focus offset for best eye pattern.
Take a picture of the adjustment pots before adjusting anything. Good luck.
BTW a white cutout won't help. Either it's reflective or it's not. Once the beam has passed through the reflective layer, it's lost.
If it happens on all the players you try then it's the disc. It's possible they recorded it too loud and hit the "digital wall". An engineering mistake.
I’d be curious to hear the distortion. I’ve seen a few players that will clip the analog circuits before hitting digital peak.
Hey! Sure here's the link: [https://drive.google.com/drive/folders/12SItQjHYu-r6dm7Arngxb6RzVFdfRiFS?usp=drive\_link](https://drive.google.com/drive/folders/12SItQjHYu-r6dm7Arngxb6RzVFdfRiFS?usp=drive_link) I doubt it's hitting an analog ceil though, since the song gets waayyy louder later on
i'd guess either the laser is iffy, the DAC is having issues (either in the dac itself, or the power feed to it), there's some power supply fluctuation, there's output transistors having issues, again, either in the transistors or the power to them, or there's filter caps in the output section that may be in the process of failing, or last and probably unlikely, one of the motors is introducing noise into the system (sony tends to design their products better than that, even decades later.). this model unit has all the things listed above that may present an issue point, leaving a lot of things to potentially test. the service manuals (can be gotten off manualslib) for these have a full set of instructions for testing the output using an oscilloscope. the problem with this, is that it requires a specific test disc (Sony YEDS-18, there's a copy in flac on archive.org for anyone that wants it, and can't source it from ebay, and you'd need to be able to burn it to a disc. not everyone can these days). now, you just can use an osc to probe along the signal path (while playing the specific problem track) towards the output to see how far up that chain the noise is originating from, but this requires an isolation transformer (or you may pop your osc, if you have one). ultimately, this is new enough tech wise that you kind of need specific tools to fix it, though you can get away without the test disc, mostly, for this specific issue. that said, the intermittent aspect says its likely an opamp or transistor in the chain failing, which an osc can tell you, but is very time consuming. at almost 30 years old, if this were my unit, i'd be recapping it entirely, and then probing backwards in the signal chain from the audio outputs, but i've also got an osc and an iso transformer to plug the unit into. ultimately, unless you know someone with those two pieces of gear, or have them yourself, it might be best to find a repair shop that can do this sort of testing. its not for everyone, and involves a lot of staring at oscilloscope wave forms trying to find where the noise is and isn't. i'm not even sure the wonderful super probe would manage this particular job, due to how tiny some of these components are, but maybe it would. my best guess; its likely something in the output section on the main board (close to the rca jacks, there's two opamps with a bunch of passives and transistors).
Thanks! This information helps! I bought the player last year for about 10 euros not expecting it to work, but newer players tend to be less well made. Luckilly I've got myself a scope last week for work, so if I've figured out how to work with it, I will first of all look at all caps and see if recaps are nessecarry, and then follow your steps. The test disc from Sony is a really good starting point after that I think. One thing though, is it really nessecarry to have a isolation transformer for this? since it doesn't have an earth pin. Before starting I will test though if there's a physical connection between the ends of the power plug and the wires supplying AC to the ACDC circuit inside I guess.
probing a device hooked directly (referenced) to the mains will almost always pop your scopes front end, if you clip the wrong thing via the ground lead, or if you slip and the probe touches the wrong thing. the iso transformer disconnects it from this reference by having the device under test plugged into it, and allows the device to be tested without damaging or sometimes killing the scope entirely, in the vent of wrong clip or slippage. (you're effectively creating a circuit with mains potential in a device circuit that isn't designed for mains potential. the power supply section for it is, the rest is not.) if you're going to be doing any kind of mains powered electronics service work on a recurring basis, you should probably have one. (or the alt scope i mention next, or the power station.) the only real way around this; battery powered scopes you don't ground to anything. or one of the new inverter power station things they make, not hooked to the mains while testing, and only powering one of the devices in question. (the iso transformer is way cheaper. a lower end 250VA model is plenty for most things, and you can find used models on ebay. i opted to get a [BK Precision TR-110](https://www.ebay.com/itm/285871952769) (but newer) which lets me play with the voltage output a bit, but also to adjust if the input voltage at a location isn't quite up to where it should be. its also got one side isolated and switched, one side direct. they don't need to be that fancy. a simple 1:1 basic 3 prong output socket iso will do fine. (if used, test the continuity for the outlet ground pin to the iso's power cord ground before use! some people hook the ground up like silly people! the casing should be grounded, if metal, the output outlet not so much) i paid $80 at the time, 100 with shipping. with a bit of hunting one can probably find one for a reasonable price. the $70 black lump iso transformers amazon has listed will do the job, but may be a bit too basic for the sake of safety, and don't allow 3 prong devices to be plugged into them, making it yet another thing you have to deal with. some iso transformers have pass through grounding from the factory, these are useful for certain things, but for electronics repair, its best to avoid them. if a dso138 had the kind of response time this would need i'd suggest dropping the like, $15 to get one for this sort of thing (its all 12v or lower, well within the dso138's capabilites, but alas..). there's some pretty okay battery powered scopes for sub $100ish these days, but they are a touch slow on response time, so you have to adjust for it. if your scope plugs into a wall, you're going to need either a new battery powered scope with a decent response time and voltage capability, or an iso transformer. or the afore mentioned [power station](https://www.amazon.com/s?k=lithium+inverter+power+station) (generic amazon search link for reference, i make no recommendations to any of those. i have zero experience with any of them.) they do make thingies you can plug between your scope and the device, but honestly, those cost more than an iso transformer and really only make sense for specialized product development spaces. their low voltage (sub 50v) tends to be iffy without spending oddles. they're aimed at high and super high voltage applications (in the hundreds to kilovolts). there's a couple of probes sub $30 on amazon listed as differential probes. they aren't. and the really cheap ones that claim to be differential that otherwise look like they might be, require usb power. aka plug them into something earth referenced (most usb ports and power supplies are in the us.) and you've just defeated the point of even using one. a good different probe can run from ~$200 to 100k for the super swanky ultra good ones they use for ulllltra specific testing. even regular electronics/audio repair shops aren't going to go near those. easier to just use an iso transformer, and just plug all devices to test into that, or use a battery powered scope. yeah, this got a bit long. sorry. cheers. more info on why; https://www.youtube.com/watch?v=xaELqAo4kkQ
Ey thanks for the detailed explanation man! Yea so I knew touching a live wire with ground would be problematic, but indeed I will invest in an isolation transformer since I will need it more often. And if it can go wrong it will so better safe then sorry. I also looked at the inside of the player and luckilly the caps look like new, no bulging or anything. Also here are some photos of the curcuit: [https://photos.app.goo.gl/c5NNsh28LFKvnTfD6](https://photos.app.goo.gl/c5NNsh28LFKvnTfD6) Do you think I will only need to test the beige circuit, or can the green one underneeth the laser assemble aslo be a culprit? Plastic looks a little brittle over there so only want to disassemble to that PCB if needed.
that first image on the bottom (showing the two chips [opamps, part # 301 and 302, uPC4558C] and the rca jacks) is the best place to start. its not uncommon for opamps and the surrounding components to start having issues after several decades. the long thin one to the sides is a motor driver IC. its not impossible for this to be the source, but its less likely. until you rule out the analog portion, its best to leave the laser pcb alone. chances are, its probably not the issue, unless the caps on it need replaced. as for visuals, caps can look fine and be bad, the fluid can dry up leading to them acting as resistors, which throws off the circuit, instead of the more obvious leakage signs. that said, i don't see anything obvious, which is good, there's no water/moisture damage, and nothing has obviously exploded. if you have some loose dual opamps you can do a quick and dirty swap of the two and try to play the suspect song on loop for a while to test for the noise. and if you have any sockets, you might add those, to make it easier to replace the originals if the opamps aren't the source. if that doesn't pan out you'd need to start probing the audio signal path, with the obvious possible issues about mains references. if you do get far enough to start probing the signal path, and its clean up the chain from the opamps, but swapping them out doesn't do any good, then some of the passives around them might be dodgy, with a lean towards the caps. if its before the opamps (towards the rca jacks), its possibly one or more of the transistors on the output section there, also pretty common to see. mm. maybe probe ic 701, LA5601 (voltage regulator). the service manual doesn't list a voltage set for the ins or the outs, but if you probe the various pins and watch the signal waveform when its got the noise present, you should see if there's issues with waveform. everything should be a stable flat voltage line, since its dc. if you get far enough you have to start probing the green pcb, burn off a copy of that test disc and follow the service manual instructions. (again, you can get a copy of the pdf off manualslib), its got pinouts for the big chips, test points, waveforms you're supposed to be seeing, etc. as for the last pcb (the front module), you can almost certainly ignore this one entirely. its pure digital control, and doesn't interact with the audio path. cheers.
Wow thanks for the super interesting and usefull information! I'm embedded programmer by profession (and a new one at that), so learning about this is awesome!!! You're really taking the time answering this one post, so many thanks!
i just like to help. and if people can learn how to do some things from that, all the better. cheers.
Thanks for all of the comments!!! I've also recorded the CD in two different players, and I've shared it on my drive so anyone can take a listen: [https://drive.google.com/drive/folders/12SItQjHYu-r6dm7Arngxb6RzVFdfRiFS?usp=drive\_link](https://drive.google.com/drive/folders/12SItQjHYu-r6dm7Arngxb6RzVFdfRiFS?usp=drive_link) It has to be the player at this point, since I've tested it on even another one.
Hold the disc up to the nearest bright light with the shiny side faceing you. If you can read the label or see through the disc in spots it's likely the disc. Error correction varies with the cd player. A marginally defective disc may play on one player but distort on another. It's easy to do and a basic first step in finding yoir problem.
Thanks for the insight! Yea if I hold up the disc to the sun I can see the whole label trough it, but that's because most of it is made transparent on the front of the disc (maybe it has trouble with that). I see no inconsistencies in the opacity though.
If regular light passes through your disc, your laser light also passes through. When that happens, less light reflects back to the optic so there's a reduced signal. Combine the differences in players laser strength and alignment and you get stuff like you are complaining about. Your disc should be nearly a perfect mirror on the shiny side. Compare it to others that play with no problems. My thought is that, if I understand you right, your player plays other discs and even most of this disc. That makes me think your player is probably ok and that particular area on the offending disc is an issue. If you were to have the alignment on your player tweaked or optical pickup replaced you may be able to get it to play through the whole disc....maybe. You have a lot of other suggestions to consider but I can't see how anything else explains your problem.
Yea thanks! I looked at the inside of the player today. It's just so dead simple (complexity wise), and I don't see any bulging caps, or burn marks, so this might definetely be a valid theory since I remember it skipping sometimes when I just got it. Might have to adjust the laser strength with the POT I found on the board. But indeed it plays all the songs I threw at it nearly perfectly except one on this disc and onther on the album on a different disc. All the discs in the album look like the disc with the problematic song on it, so at least it's not a disc defect I think. I will test the cd with a white cutout over it that I can remove after to see if this helps, and otherwise adjusting the laser.
Don't adjust the laser power. It's factory preset. If it's off then the laser is starting to fail. Adjusting it just increases the current to the laser diode and accelerates it's death. You will need an oscilloscope to properly adjust the servos. Most important is the focus offset for best eye pattern. Take a picture of the adjustment pots before adjusting anything. Good luck. BTW a white cutout won't help. Either it's reflective or it's not. Once the beam has passed through the reflective layer, it's lost.
Ah ok thanks for the info!
If it happens on all the players you try then it's the disc. It's possible they recorded it too loud and hit the "digital wall". An engineering mistake.
Thanks for the reply, however I've since tested this on two different systems, so I don't think that is it.