Hi Karl,
Yes, I think so too. Thank you.
All,
As for the KSS-240A, you'd best not touch any of those pots as they are not marked. Hit the E-F balance (tracking offset) and you're in trouble. Hit the laser power, and you might be toast. Obviously if you have the equipment and know exactly what you are doing, sometimes you can make an improvement. Often, no improvement is possible. I won't say much more than that simply because I don't want to encourage people to mess with those controls. Even most working techs should leave them alone!
Please, do not touch the controls on the KSS-240A. That head is pretty much plug and play. If the focus is out, the table height is more likely to be out than the adjustment.
-Chris
Yes, I think so too. Thank you.
All,
As for the KSS-240A, you'd best not touch any of those pots as they are not marked. Hit the E-F balance (tracking offset) and you're in trouble. Hit the laser power, and you might be toast. Obviously if you have the equipment and know exactly what you are doing, sometimes you can make an improvement. Often, no improvement is possible. I won't say much more than that simply because I don't want to encourage people to mess with those controls. Even most working techs should leave them alone!
Please, do not touch the controls on the KSS-240A. That head is pretty much plug and play. If the focus is out, the table height is more likely to be out than the adjustment.
-Chris
Sony CDP-C201 5-disc changer update:
This machine worked great earlier when I was playing only one disc. But the roulette wheel didn't need to rotate from one disc to the next during that test. This fault only got discovered after I filled up the tray with 5 discs.
First issue: Occasionally the roulette wheel didn't rotate all the way to the next disc.
It also made a slight grinding noise while rotating. Trying a fresh belt made no difference at all (the old belt didn't slip).
Then I observed the wheel drive motor made a (barely audible) whining noise when it stalled out just before reaching the next index position. Giving the wheel a bit of a push at this time would temporarily "fix" the problem and then the next disc would play. The "whining noise" is from PWM applied to the wheel motor to cause it to slow down just before detection of the next index position (I'm a bit surprised at how sophisticated the design engineers were).
After more checking and inspection I observed the roulette wheel had way too much friction. It didn't rotate easily. This extra friction caused the motor to stall just before reaching the next index position.
After considerable head-scratching I determined the plastic roulette wheel itself is slightly warped in the shape of an umbrella: Its center is higher than its circumference. The wheel is difficult to rotate when the center pivot bolt is tightened normally. Loosening the center pivot bolt by a couple of turns frees it up. So I took out the center pivot bolt and placed one steel washer underneath it to shim it up. This totally freed up the roulette wheel. Now the wheel rotates smoothly and freely with the center pivot bolt tightened at the normal torque.
Second issue: The disc platter which is part of the transport/pickup assembly often bumped into the tray assembly while the tray was opening/closing.
The tray didn't get stuck but clicking noises could be heard. Close examination confirmed the transport assembly didn't tilt down far enough to avoid touching the tray. This issue was caused by one missing part: There is a metal post on the transport frame which engages with the cam wheel which raises/lowers the transport frame. This post is supposed to have a "roller" on it where it engages with the ramp tracks on the cam wheel (roller part number is Sony p/n 4-927-631-01). I vaguely recall having some of these rollers on hand many years ago because they tended to get lost when disassembling these machines for repair. But instead of searching through boxes of old parts I fabricated a new "roller" from a short length of nylon tubing. It works perfectly.
After operating it for 12 more hours in "repeat all 5 discs" mode it is still going strong.
-EB
Well, the wheel and tray didn't always work perfectly after loading up 5 discs and putting the machine on "repeat all 5 discs."
This machine worked great earlier when I was playing only one disc. But the roulette wheel didn't need to rotate from one disc to the next during that test. This fault only got discovered after I filled up the tray with 5 discs.
First issue: Occasionally the roulette wheel didn't rotate all the way to the next disc.
It also made a slight grinding noise while rotating. Trying a fresh belt made no difference at all (the old belt didn't slip).
Then I observed the wheel drive motor made a (barely audible) whining noise when it stalled out just before reaching the next index position. Giving the wheel a bit of a push at this time would temporarily "fix" the problem and then the next disc would play. The "whining noise" is from PWM applied to the wheel motor to cause it to slow down just before detection of the next index position (I'm a bit surprised at how sophisticated the design engineers were).
After more checking and inspection I observed the roulette wheel had way too much friction. It didn't rotate easily. This extra friction caused the motor to stall just before reaching the next index position.
After considerable head-scratching I determined the plastic roulette wheel itself is slightly warped in the shape of an umbrella: Its center is higher than its circumference. The wheel is difficult to rotate when the center pivot bolt is tightened normally. Loosening the center pivot bolt by a couple of turns frees it up. So I took out the center pivot bolt and placed one steel washer underneath it to shim it up. This totally freed up the roulette wheel. Now the wheel rotates smoothly and freely with the center pivot bolt tightened at the normal torque.
Second issue: The disc platter which is part of the transport/pickup assembly often bumped into the tray assembly while the tray was opening/closing.
The tray didn't get stuck but clicking noises could be heard. Close examination confirmed the transport assembly didn't tilt down far enough to avoid touching the tray. This issue was caused by one missing part: There is a metal post on the transport frame which engages with the cam wheel which raises/lowers the transport frame. This post is supposed to have a "roller" on it where it engages with the ramp tracks on the cam wheel (roller part number is Sony p/n 4-927-631-01). I vaguely recall having some of these rollers on hand many years ago because they tended to get lost when disassembling these machines for repair. But instead of searching through boxes of old parts I fabricated a new "roller" from a short length of nylon tubing. It works perfectly.
After operating it for 12 more hours in "repeat all 5 discs" mode it is still going strong.
-EB
Thanks!Those multi disc tray players were never that good (speaking generally across all makes and models) and tbh I never liked working on the mechanics of the ones we dealt in... which were mainly Philips and Aiwa.
Sounds like you have done a good job with this one though
I’ve never been a big fan of multi-disc players either. All of the disc players in my own personal audio systems are single-disc units. But there are plenty of people who actually want multi-disc CD players so I’ll be more than happy to sell these after I get them into working condition.
Also I wanted to check out every CD player in my collection (hoard?) which has a KSS-240A in it. I learn a lot when my workbench has several similar units on it at the same time which I can compare to each other.
-EB
The CDP970 used the PCM63 dac chip. The reason many of the older Sony CDPs sounded thin and had lack of low end was due to the smaller value coupling caps at the outputs. Bumping up their size helped this.
I have owned many KSS240 equipped players and they were very reliable. The only time I had skipping problems was due to a dirty lens or bad servo caps / transistors.
I have owned many KSS240 equipped players and they were very reliable. The only time I had skipping problems was due to a dirty lens or bad servo caps / transistors.
I think Denon was the better bet. They used Sony transports (KSS-151A being really good), Sony servo / DSP chip sets, and then a higher quality audio section. The better Denon CD players have always been my favorite. I'm looking at a DCD-2560GL now. I just got a DCD-2560, but the champagne gold looks really nice. I do have a DCD-S10 that I bought new as well. I improved the audio section and it really sounds excellent! That is a KSS-240A transport.
I totally agree that Denon does a terrific job making “musical sounding” CD players with Sony optical pickups and Sony servo/decoder IC chips.
I think a large part of this is from Denon using better DACs vs. typical Sony machines.
Many Sony DACs which tend to sound “thin” use a form of PWM (Sony’s “Pulse DAC” concept). This gradually evolved into the DSD system employed by the SACD format. But Sony’s early versions didn’t have a high enough clock rate to preserve “musicality.” To me a well-encoded MP3 file can actually sound better than these 1990-vintage Sony pulse DACs.
In contrast Denon was using true-PCM DACs with 16-bit or better linearity during the 1980’s/1990’s. And Denon stayed with this architecture.
Another difference is that Sony used only +/-5V rails for the analog output stage opamps. And those rails were shared with the servo and digital logic. Some Denon models have independent +/-9V or +/-12V rails to power the opamps.
I doubt these differences in “musicality” can be entirely explained by the differing uF values of the analog audio output coupling capacitors. I frequently replace factory original polarized 10-47uF coupling caps with high-grade 100uF bipolar caps. I use bipolar caps because standard polarized electrolytics can be nonlinear when there is no DC voltage across them. However I only observe modest sonic improvements from upgrading output coupling caps.
I’ll save additional thoughts about modifications for other threads. In this thread I want to stay focused on getting my vintage KSS-240A CD players into working condition.
For now I’ll confirm that I hear a difference between a typical Sony “pulse DAC” CD player vs. a Denon (or Philips) with actual PCM DACs. I hear this even through the modest speakers on my workbench. I have CD’s on my workbench that I’ve heard hundreds of times. I rarely feel “hey this really sounds awesome” when listening to Sony CD players.
-EB
I’ll look for a Sony CDP-970. It’s “garage sale season” where I live. Older CD players often get priced at $5 or $10 USD.
I always like the sound of CD players that have the Burr-Brown PCM-series DACs.
-EB
Sony CDP-C201 5-disc changer update:
My Sony CDP-C201 has continued to operate perfectly in "repeat all 5 discs" mode for several days after I fixed the mechanical issues with the tray and carousel wheel.
I’m going to set the Sony player aside while I revisit my Denon DCM-320. The replacement servo IC chip for the Denon arrived yesterday.
I’ll install the servo chip and then do a bit of listening to both machines. My recollection about the Denon is that it sounded really great (when it decided to work). In contrast, audio quality from the Sony is tolerable (and I’m being generous when I say this).
I also have an Onkyo 6-disc CD changer which needs to get onto the workbench for its initial checkout. All 3 of these CD changers have a KSS-240A transport section.
-EB
My Sony CDP-C201 has continued to operate perfectly in "repeat all 5 discs" mode for several days after I fixed the mechanical issues with the tray and carousel wheel.
I’m going to set the Sony player aside while I revisit my Denon DCM-320. The replacement servo IC chip for the Denon arrived yesterday.
I’ll install the servo chip and then do a bit of listening to both machines. My recollection about the Denon is that it sounded really great (when it decided to work). In contrast, audio quality from the Sony is tolerable (and I’m being generous when I say this).
I also have an Onkyo 6-disc CD changer which needs to get onto the workbench for its initial checkout. All 3 of these CD changers have a KSS-240A transport section.
-EB
Well, maybe I'm biased?
To me this Sony CDP-C201 sounded only "OK" compared to other CD players I've been listening to recently. But I was thinking the Sony CDP-C201 had a Sony "pulse DAC."
However, the Sony CDP-C201 uses a TDA1543A. Most people (including myself) would agree the TDA1543A is capable of sounding quite good.
There are other items in the Sony CDP-C201 which could be improved:
- The I-V converter opamp is an RC4558P with +/-5V supply voltages. Not the worst possible choice but certainly not the best either. I prefer a well-regulated +/-12V power source for the I-V converter stage along with an 8-pin DIP socket for easy substitution of better opamps.
- Audio output coupling caps are generic 100uF 25V polarized. I prefer premium-grade "non-polar" electrolytics for this application. I'll change these caps before I take it upstairs to hear it through my main audio system. This is the only mod I intend to install now.
- The output muting circuit (Q501, Q551) could be an issue. I really need to study these muting circuits. I know that some people suggest removing them entirely.
-EB
Hi EB,
Those muting transistors should be 2SC2878. Those are designed with very high reverse E-B breakdown voltage and cannot be replaced with a normal transistor. But only an idiot would just remove them! If you pull the muting transistors, you must install something to do the same job. I'll assume you would install a relay to short the signal to ground when muted. That's what the better machines use.
TDA1543A is a budget DAC. Not a great choice, but some folks champion things just because they are cheap. Like NAD product, which isn't very good at all. The use of an RC4558P is just more down that cheap road, same as running everything off the bipolar 5 V rails. Cheap, cheap, cheap. You do know the 4558 is a slightly souped up 741 - right? Another cheap op amp, the 5532, would be a massive upgrade. Those are also very old, but more highly engineered op amp. Still more than good for audio in that location.
I wouldn't bother with the output capacitors unless you replaced the filter capacitors (probably polyester - yuk!) first, and used at least 5532 op amps. Anything better would be a waste on a TDA1543A, but that is just my opinion.
-Chris
Those muting transistors should be 2SC2878. Those are designed with very high reverse E-B breakdown voltage and cannot be replaced with a normal transistor. But only an idiot would just remove them! If you pull the muting transistors, you must install something to do the same job. I'll assume you would install a relay to short the signal to ground when muted. That's what the better machines use.
TDA1543A is a budget DAC. Not a great choice, but some folks champion things just because they are cheap. Like NAD product, which isn't very good at all. The use of an RC4558P is just more down that cheap road, same as running everything off the bipolar 5 V rails. Cheap, cheap, cheap. You do know the 4558 is a slightly souped up 741 - right? Another cheap op amp, the 5532, would be a massive upgrade. Those are also very old, but more highly engineered op amp. Still more than good for audio in that location.
I wouldn't bother with the output capacitors unless you replaced the filter capacitors (probably polyester - yuk!) first, and used at least 5532 op amps. Anything better would be a waste on a TDA1543A, but that is just my opinion.
-Chris
Hi Karl,
Interesting. I'll have to check the reverse hFE.
I really do not like his invention of a new symbol. It is an NPN transistor and the symbol should remain the same. Otherwise he is telling me there are two emitters and no collector. This is not true.
I just measured > 500 beta in the normal connection and around 200 with emitter and collector reversed. So, much more symmetrical than a normal transistor, but I wouldn't use that word because the two gains are very different.
Failure mode. I don't agree with him They just die in systems that have remained connected for years. I don't buy the ESD suggestion - although that can certainly kill them. I think the failure mode has more to do with high reversed bias voltage across the junction than anything else.
Interesting. I'll have to check the reverse hFE.
I really do not like his invention of a new symbol. It is an NPN transistor and the symbol should remain the same. Otherwise he is telling me there are two emitters and no collector. This is not true.
I just measured > 500 beta in the normal connection and around 200 with emitter and collector reversed. So, much more symmetrical than a normal transistor, but I wouldn't use that word because the two gains are very different.
Failure mode. I don't agree with him They just die in systems that have remained connected for years. I don't buy the ESD suggestion - although that can certainly kill them. I think the failure mode has more to do with high reversed bias voltage across the junction than anything else.
Today’s update:
New CXA1372S servo IC arrived yesterday from China.
I installed it.
I put the player on repeat with 5 discs in it.
It is still operating perfectly after running all night long.
Also: This machine sounds really great. I don’t think I’ve heard any other multi-disc player sound this good.
-EB
So true!Well that sounds promisingIt's never 'the big chip' except now and again it is
Some items have certain "high failure rate" parts which are well known.
We can refer to them as "the usual suspects."
Example: Optical pickups & spindle motors in CD players.
But it's not always that "high failure rate" part every time.
I have a new problem:
It's more fun to listen to this Denon DCM-320 than it is to reassemble it and put a different machine onto my workbench.
So instead of finishing it I'm cleaning my workbench while I listen to it.
-EB