Hello,
I´ll have to do some adjustment on my Nakamichi from ´86, which basically is a Sony.
Unluckily, I´ll also have to make an adjustment, which is seldomly required.
You can find the description of the adjustment in the file attached.
(It was not very well translated I guess.)
What troubles me is step 5 of the adjustment procedure:
I´ll need asignal generator, but could use my other CD-Player, playing the test tone needed. (it has to be fed to an IC for adjustment)
The maximum level is 2.5 V at 50 kiloohms, Load impedance over 1 Kiloohm, how do I get 300mV at 220kilohms from that? Could anybody do the math for me?
Also, a bandpassfilter is needed for adjustment. I could loop the signal through my mixing console and apply a filter there before monitoring the resulting signal on the scope (I guess also a peakmeter is needed, but is not mentioned in the service manual.)
Maybe, somebody knows, how steep/flat this band pass filter should be?
All the best,
Salar
I´ll have to do some adjustment on my Nakamichi from ´86, which basically is a Sony.
Unluckily, I´ll also have to make an adjustment, which is seldomly required.
You can find the description of the adjustment in the file attached.
(It was not very well translated I guess.)
What troubles me is step 5 of the adjustment procedure:
I´ll need asignal generator, but could use my other CD-Player, playing the test tone needed. (it has to be fed to an IC for adjustment)
The maximum level is 2.5 V at 50 kiloohms, Load impedance over 1 Kiloohm, how do I get 300mV at 220kilohms from that? Could anybody do the math for me?
Also, a bandpassfilter is needed for adjustment. I could loop the signal through my mixing console and apply a filter there before monitoring the resulting signal on the scope (I guess also a peakmeter is needed, but is not mentioned in the service manual.)
Maybe, somebody knows, how steep/flat this band pass filter should be?
All the best,
Salar
Hi Salar,
Adjust the gain while the unit is playing a CD normally. The sweet spot is just after the low frequency content settles down and before the high frequency noise gets larger. Standard Sony method, works well for me.
One problem I've noticed with those heads is that the pole piece gets sticky with the lens assembly. Watch for sticky heads. You can't clean them either.
I also PM'd you the same response, but posted for the benefit of other members.
-Chris
Edit: The transport is from NEC.
Adjust the gain while the unit is playing a CD normally. The sweet spot is just after the low frequency content settles down and before the high frequency noise gets larger. Standard Sony method, works well for me.
One problem I've noticed with those heads is that the pole piece gets sticky with the lens assembly. Watch for sticky heads. You can't clean them either.
I also PM'd you the same response, but posted for the benefit of other members.
-Chris
Edit: The transport is from NEC.
Hi Chris!
Thanks for the quick reply - so a frequency generator is not needed?
What about a test CD - is the Test - CD from Philips you mentioned in the KSS-151 thread available somewhere? (Looks like the YEDS-18 CD´s from Sony are sold out)
Do you have the name/part number of the Test-CD?
But I can imagine, that a well manufactured Audio CD will help as well, especially CD´s from the beginning of that era, from which I assume, that specifications were very tight...
All the best,
Salar
BTW, my english is not perfect, what is a pole piece?
Thanks for the quick reply - so a frequency generator is not needed?
What about a test CD - is the Test - CD from Philips you mentioned in the KSS-151 thread available somewhere? (Looks like the YEDS-18 CD´s from Sony are sold out)
Do you have the name/part number of the Test-CD?
But I can imagine, that a well manufactured Audio CD will help as well, especially CD´s from the beginning of that era, from which I assume, that specifications were very tight...
All the best,
Salar
BTW, my english is not perfect, what is a pole piece?
Hi Salar,
For gain adjustments it's critical that the exact test disc specified be used. Since you are not following the service manual, pick out a good defect free CD. Monitor the RF (or EYE pattern) and use the disc with a large, clear and stable RF pattern. This will minimize servo noise.
Tracking gains are not precise really. What you do is monitor the tracking error or output terminal. Note where the the controls are before you start. Turn the gain down slightly until the wave starts showing a low frequency component. Then turn it up until the low frequency component is greatly reduced and high frequency noise starts to show up. Back the control off in between these two points. You can increase or decrease the gain from this point a little. Car decks tend more to a little high frequency noise (helps track with bumps). A home machine may want the gain a little lower (doesn't over react to defects on the disc).
Now you know my tuning secrets.
On a KSS-123A, the lens and coils ride up and down around a central pole. There is a bearing in the lens assembly. Anything in there will gum things up. I've tried everything with no luck once these get sticky. Often that is what causes head replacement on these.
Salar, your English is just fine from my end.
-Chris
For gain adjustments it's critical that the exact test disc specified be used. Since you are not following the service manual, pick out a good defect free CD. Monitor the RF (or EYE pattern) and use the disc with a large, clear and stable RF pattern. This will minimize servo noise.
Tracking gains are not precise really. What you do is monitor the tracking error or output terminal. Note where the the controls are before you start. Turn the gain down slightly until the wave starts showing a low frequency component. Then turn it up until the low frequency component is greatly reduced and high frequency noise starts to show up. Back the control off in between these two points. You can increase or decrease the gain from this point a little. Car decks tend more to a little high frequency noise (helps track with bumps). A home machine may want the gain a little lower (doesn't over react to defects on the disc).
Now you know my tuning secrets.
On a KSS-123A, the lens and coils ride up and down around a central pole. There is a bearing in the lens assembly. Anything in there will gum things up. I've tried everything with no luck once these get sticky. Often that is what causes head replacement on these.
Salar, your English is just fine from my end.
-Chris
Hi chris!
Thanks a lot for the exact description! I am collecting CD´s for about 20 years, so I guess, one perfectly manufactured can be found. I hope, the assemby will not gum up when being stored. I guess I will need the next replacement at least seven yeras ahead. The units I bought were spare parts for AKAI, btw.
All the best,
Salar
Thanks a lot for the exact description! I am collecting CD´s for about 20 years, so I guess, one perfectly manufactured can be found. I hope, the assemby will not gum up when being stored. I guess I will need the next replacement at least seven yeras ahead. The units I bought were spare parts for AKAI, btw.
All the best,
Salar
Hi Chris!
Which fact do you mean? Did Sony fix the "pole problem" in later stocks? Maybe, the KSS-123A should be stored with the lens facing upward?
I will make the readjustment when I get some good electrolytic capacitors for the D/A board - maybe you noticed that I redesigned the cabinet, but now it has become more complicated to open the player, so i want to do everything on one occasion. I replaced the original Nichicons for some 105Grade(Celsius) types, but the Nak now lacks a little bit of bass and the treble does not sound clear anymore. Unfortunately, Panasonic FC / Nichicons / OsCons are not easy to get here in Berlin, but somebody here sells Blackgates - for about 35U$ each ... argh
All the best,
Salar
Which fact do you mean? Did Sony fix the "pole problem" in later stocks? Maybe, the KSS-123A should be stored with the lens facing upward?
I will make the readjustment when I get some good electrolytic capacitors for the D/A board - maybe you noticed that I redesigned the cabinet, but now it has become more complicated to open the player, so i want to do everything on one occasion. I replaced the original Nichicons for some 105Grade(Celsius) types, but the Nak now lacks a little bit of bass and the treble does not sound clear anymore. Unfortunately, Panasonic FC / Nichicons / OsCons are not easy to get here in Berlin, but somebody here sells Blackgates - for about 35U$ each ... argh
All the best,
Salar
Hi Salar,
I don't think it matters which way they are stored. On the side might be best.
I've found the 105 ° caps are not as good electrically as the 85 ° caps. Bypass big ones with 1 uF box films. Anything that is 4u7 and below can be replaced by Wima film types (thanks again MikeB!). I suspect a bypassed 85 ° might be as good as a blackgate, just a guess.
-Chris
After I used a lot. I did sell a few and kept a couple for my own machine.
I don't think it matters which way they are stored. On the side might be best.
I've found the 105 ° caps are not as good electrically as the 85 ° caps. Bypass big ones with 1 uF box films. Anything that is 4u7 and below can be replaced by Wima film types (thanks again MikeB!). I suspect a bypassed 85 ° might be as good as a blackgate, just a guess.
-Chris
Hi Chris,
finished the electronical adjustment today (5.00 am)
Well, unluckily I could not adjust the tracking gain with a scope - the pins of the scope did kind of shorten the amp for the tracking circuit - even with using a resistor of one megaohms.
But what seemed to help was monitoring the time the laser takes, when it has to jump from the first to the last track and vice versa. Nak sometimes almost semed to fail when doing so.
After some time of "just travelling" the motors/servos switches to some kind of audible search mode for some moments, (one hears them "cirping") until the beginning of the track is found and the motors run silent again.
I adjusted the tracking gain in a way that this moment does take as less time as possible and sounds "precise"
Putting the gain high results in a hissing noise, I guess? (Lenscoils?)
This was the way it was before. Now the Nak is still not fast (about 5-6 seconds from the first to the last track, lets say 50 minutes of disc time to travel), but was maybe a second faster, when I bought it.
Again, thanks for your help,
All the best,
Salar
finished the electronical adjustment today (5.00 am)
Well, unluckily I could not adjust the tracking gain with a scope - the pins of the scope did kind of shorten the amp for the tracking circuit - even with using a resistor of one megaohms.
But what seemed to help was monitoring the time the laser takes, when it has to jump from the first to the last track and vice versa. Nak sometimes almost semed to fail when doing so.
After some time of "just travelling" the motors/servos switches to some kind of audible search mode for some moments, (one hears them "cirping") until the beginning of the track is found and the motors run silent again.
I adjusted the tracking gain in a way that this moment does take as less time as possible and sounds "precise"
Putting the gain high results in a hissing noise, I guess? (Lenscoils?)
This was the way it was before. Now the Nak is still not fast (about 5-6 seconds from the first to the last track, lets say 50 minutes of disc time to travel), but was maybe a second faster, when I bought it.
Again, thanks for your help,
All the best,
Salar
Hi Chris,
on the board, there are no Fo and To (what do the abbreviations stand for?) test pins but an "Eye P.T" (Pattern?).
But "Eye" is not described for adjustment in the service manual.
Chris, you have a copy of the service manual?
Then I can give you some details:
As one example, Step 4 in the adjustment procedure (E-F balance adjustemt, page 4 and page 28) does not work as described. I always have the "symmetrical swing" described on the scope, distorted by dropouts (longer swings). Using several Cs did not help. The frequency of those dropouts does not change much when I turn the variable resistor.
But just to make two basic things clear to me, so that I can be shure I did nothing wrong:
Raising/lowering the voltage means that the whole wavefom on a scope travels up/down horizontally?
(Step 3, focus servo adjustment, page 6 and 30)
Can the ground of a probe being connected to any ground of the unit?
Or, as a general rule, always as close to the test pin as possible?
Or, as another example, when i have to shorten the test mode pin to the ground pin, the ground of the probe should also be connected there? I always attached the "ground probe" to the cabinet when measuring, maybe this was wrong for some measurements?
I bought a very old scope for testing, still being based on valves, (From Philips, looking for its name in the web lead me to the page of a museum for roentgen tubes)
I had to make the test probes myself, being connected to a BNC jack.
One for the signal, another being connected to the scielding of the BNC.
I borrowed a scope two years ago from a TV shop (not possible any more) and the signals of the philips do look as I remember them from that time, so I think, I did not make anything wrong with my DIY probes..
Al the best,
Salar
on the board, there are no Fo and To (what do the abbreviations stand for?) test pins but an "Eye P.T" (Pattern?).
But "Eye" is not described for adjustment in the service manual.
Chris, you have a copy of the service manual?
Then I can give you some details:
As one example, Step 4 in the adjustment procedure (E-F balance adjustemt, page 4 and page 28) does not work as described. I always have the "symmetrical swing" described on the scope, distorted by dropouts (longer swings). Using several Cs did not help. The frequency of those dropouts does not change much when I turn the variable resistor.
But just to make two basic things clear to me, so that I can be shure I did nothing wrong:
Raising/lowering the voltage means that the whole wavefom on a scope travels up/down horizontally?
(Step 3, focus servo adjustment, page 6 and 30)
Can the ground of a probe being connected to any ground of the unit?
Or, as a general rule, always as close to the test pin as possible?
Or, as another example, when i have to shorten the test mode pin to the ground pin, the ground of the probe should also be connected there? I always attached the "ground probe" to the cabinet when measuring, maybe this was wrong for some measurements?
I bought a very old scope for testing, still being based on valves, (From Philips, looking for its name in the web lead me to the page of a museum for roentgen tubes
)I had to make the test probes myself, being connected to a BNC jack.
One for the signal, another being connected to the scielding of the BNC.
I borrowed a scope two years ago from a TV shop (not possible any more) and the signals of the philips do look as I remember them from that time, so I think, I did not make anything wrong with my DIY probes..
Al the best,
Salar
Hi Salar,
FO = Focus Output, TO = tracking output. It is important your probe is a high frequency type to view the Eye Pattern (RF) signal. You need to be able to use a horizontal setting of 0.5us / div to see it clearly. I fear your scope is not up to the task. I see from the manual that we are actually looking at the signals before amplification. Therefore the impedances here are higher too. Your scope probes are very important.
Please try to get access to a newer scope.
Steps 2,3 and 4 use your scope with DC coupling. Step 4 is critical and rather touchy. I normally start with this setup then fine tune it with the test CD's as I described earlier. Do the setup after allowing the CD player to warm up for 1/2 hour.
The new 20 MHz scopes will do this work comfortably. You should consider getting one. To bad we didn't live closer. I could whiz through this rather quickly.
Are there any other members close to you that you can barge in on?
-Chris
FO = Focus Output, TO = tracking output. It is important your probe is a high frequency type to view the Eye Pattern (RF) signal. You need to be able to use a horizontal setting of 0.5us / div to see it clearly. I fear your scope is not up to the task. I see from the manual that we are actually looking at the signals before amplification. Therefore the impedances here are higher too. Your scope probes are very important.
Please try to get access to a newer scope.
Steps 2,3 and 4 use your scope with DC coupling. Step 4 is critical and rather touchy. I normally start with this setup then fine tune it with the test CD's as I described earlier. Do the setup after allowing the CD player to warm up for 1/2 hour.
The new 20 MHz scopes will do this work comfortably. You should consider getting one. To bad we didn't live closer. I could whiz through this rather quickly.
Are there any other members close to you that you can barge in on?
-Chris
Hello Chris,
again, thanks a lot. Yes, too bad we do not live closer, but maybe beaming will be invented soon (Maybe Ocean´s XX will use it first)
But nobody around in Berlin to take a look...
The scope can run until 15Mhz, a 10X amplification is implemented, so 0.5us/div is no problem (But DC coupling means to connect the ground of the scope directly to the chassis?)
Maybe a clear signal as described in step 4 can only be seen with a proper test disc with no tolerances? (Tried about 4 CD´s, but the results looked the same.)
But is there any way to monitor the error correction? I mean, that´s what this adjustment is about - if the error correction rarely switches on, my adjustment is sufficient...
Have a nice Sunday (mine is almost over),
Salar
again, thanks a lot. Yes, too bad we do not live closer, but maybe beaming will be invented soon (Maybe Ocean´s XX will use it first)
But nobody around in Berlin to take a look...
The scope can run until 15Mhz, a 10X amplification is implemented, so 0.5us/div is no problem (But DC coupling means to connect the ground of the scope directly to the chassis?)
Maybe a clear signal as described in step 4 can only be seen with a proper test disc with no tolerances? (Tried about 4 CD´s, but the results looked the same.)
But is there any way to monitor the error correction? I mean, that´s what this adjustment is about - if the error correction rarely switches on, my adjustment is sufficient...
Have a nice Sunday (mine is almost over),
Salar
Hi Salar,
A happy servo is one that generates the least noise (ie it doesn't have to work hard). That's what you are looking for. With your old 'scope you may have to look right at the connections for the focus and tracking coils. You must set the DC offsets using the test points indiciated.
I have a feeling your oscilloscope is to noisy to work with. How much work do you do? I am wondering if it's not time for you to buy a new, inexpensive 'scope, or a newish used 'scope. I can't see any other way for you to get this done unless there is another member you can get help from.
Salar, have yourself a good Sunday too. It's 5:22 PM here where I am.
-Chris
A happy servo is one that generates the least noise (ie it doesn't have to work hard). That's what you are looking for. With your old 'scope you may have to look right at the connections for the focus and tracking coils. You must set the DC offsets using the test points indiciated.
I have a feeling your oscilloscope is to noisy to work with. How much work do you do? I am wondering if it's not time for you to buy a new, inexpensive 'scope, or a newish used 'scope. I can't see any other way for you to get this done unless there is another member you can get help from.
Salar, have yourself a good Sunday too. It's 5:22 PM here where I am.
-Chris
Hi Chris!
Well, the adjustment of the nakamichi would be the only work to do. The only sorurce for me for buying a scope to me would be ebay - I´ve seen even trashy scopes (10Mhz) being sold for about 150€ and more. Too much for me for this single work.
But the measurements I took with my scope, which I bought from a used electronics shop for 30€ some weeks ago, look the same as two years ago, when I borrowed a standard scope (A Panasonic scope) from a company I worked with. (They are specialized in digital projection for exhibitions, music events etc.) The technicians later got a lot of trouble with their boss for giving away their scope for one night, so this source is "closed".
I would rather like to get hold on a YEDS-18 test disc (or something equal, because no special tracks have to be played for adjustment ... ) any ideas from where to get one?
All the best, Salar
Well, the adjustment of the nakamichi would be the only work to do. The only sorurce for me for buying a scope to me would be ebay - I´ve seen even trashy scopes (10Mhz) being sold for about 150€ and more. Too much for me for this single work.
But the measurements I took with my scope, which I bought from a used electronics shop for 30€ some weeks ago, look the same as two years ago, when I borrowed a standard scope (A Panasonic scope) from a company I worked with. (They are specialized in digital projection for exhibitions, music events etc.) The technicians later got a lot of trouble with their boss for giving away their scope for one night, so this source is "closed".
I would rather like to get hold on a YEDS-18 test disc (or something equal, because no special tracks have to be played for adjustment ... ) any ideas from where to get one?
All the best, Salar
Hi Salar,
Forget about the YEDS-18. I've never needed it. Just pick out the discs with the best eye pattern and use those. If you want to get a great alignment CD, the one from Pierre Vernally (two disc set) is excellent. I think I want to pick up another since mine is pretty scratched by now. It was $50 US the last time I bought one. It has tracks that I use to fine tune E-F balance.
Your servo adjustments will result in the cleanest, most stable (lowest jitter) RF pattern. This coincides with the least servo noise. A touch extra tracking gain will help the player not skip from vibration but make it more sensitive to defects.
-Chris
Forget about the YEDS-18. I've never needed it. Just pick out the discs with the best eye pattern and use those. If you want to get a great alignment CD, the one from Pierre Vernally (two disc set) is excellent. I think I want to pick up another since mine is pretty scratched by now. It was $50 US the last time I bought one. It has tracks that I use to fine tune E-F balance.
Your servo adjustments will result in the cleanest, most stable (lowest jitter) RF pattern. This coincides with the least servo noise. A touch extra tracking gain will help the player not skip from vibration but make it more sensitive to defects.
-Chris
Thread Overview and Gallery arround KSS Series from Sony
in this case this thread could be of interest (include a little gallery and some schematic samples):
http://www.diyaudio.com/forums/digi...ailable-optical-pickups-sonys-kss-series.html
in this case this thread could be of interest (include a little gallery and some schematic samples):
http://www.diyaudio.com/forums/digi...ailable-optical-pickups-sonys-kss-series.html
Hi tiefbassuebertr,
I understand that you are trying to help, but you must refrain from posting links to your thread in all other threads. Besides, your thread has nothing to do with what Salar is trying to accomplish here.
Did you just search "CD Laser head" and post in every single one of them? Again, don't do this any more. Your threads can stand on their own just like everyone else's threads can.
-Chris
I understand that you are trying to help, but you must refrain from posting links to your thread in all other threads. Besides, your thread has nothing to do with what Salar is trying to accomplish here.
Did you just search "CD Laser head" and post in every single one of them? Again, don't do this any more. Your threads can stand on their own just like everyone else's threads can.
-Chris
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