anatech said:
One of the first things to do is convert the stopped clock system to a continuous clock one. It is necessary to count clock cycles in order to reposition WS relative to the now continuously moving data. The two missing clock cycles would have loomed rather large on the scope. Not that it actually matters as data is always 16 bits. Data and STR1 is the minimum requirement.
Nakamichi om5 se
Dear Anatech,
Please could you help me out.
I have a Nakamichi OM5 SE.
The sound is superb but it will not always play a disc first time and will spit it out.
Also it will sometimes not play the first or last track of a CD.
I have read all your comments but when I have taken the lid off I havnt a clue where to begin.
If you have a paypal account I am more than willing to pay you for your advice in taking the thing to bits.
Best wishes
Kwasiaesem
Dear Anatech,
Please could you help me out.
I have a Nakamichi OM5 SE.
The sound is superb but it will not always play a disc first time and will spit it out.
Also it will sometimes not play the first or last track of a CD.
I have read all your comments but when I have taken the lid off I havnt a clue where to begin.
If you have a paypal account I am more than willing to pay you for your advice in taking the thing to bits.
Best wishes
Kwasiaesem
Hi Kwasiaesem,
Please check the feed belt. It is beginning to slip. What should be done is to remove the slide rail very carefully. Retain all washers and hardware, work on a well lit, clean table. Clean the slide rail and then lubricate it using a fine oil, no additives. Make sure there is a very thin film only. There should be no visible drips when you are done, just a very thin coating of fine oil. Clean any dust out of the head area and bearing area on the head itself. Reinstall the rod and reassemble the rest.
Before placing the belt back, clean all surfaces the belt runs on. Clean the belt carefully. You may find it slips on the motor shaft. If another belt is not available, place a bit of heat shrink tubing on the motor shaft and carefully shrink it into place. Now it will work if everything else was done correctly.
At no time do you disconnect any wires from the head.
If you wish to pay someone, please make a donation to DiyAudio. That would make me a happy camper.
Let me know how this works out for you.
-Chris
Please check the feed belt. It is beginning to slip. What should be done is to remove the slide rail very carefully. Retain all washers and hardware, work on a well lit, clean table. Clean the slide rail and then lubricate it using a fine oil, no additives. Make sure there is a very thin film only. There should be no visible drips when you are done, just a very thin coating of fine oil. Clean any dust out of the head area and bearing area on the head itself. Reinstall the rod and reassemble the rest.
Before placing the belt back, clean all surfaces the belt runs on. Clean the belt carefully. You may find it slips on the motor shaft. If another belt is not available, place a bit of heat shrink tubing on the motor shaft and carefully shrink it into place. Now it will work if everything else was done correctly.
At no time do you disconnect any wires from the head.
If you wish to pay someone, please make a donation to DiyAudio. That would make me a happy camper.
Let me know how this works out for you.
-Chris
Thank you
Dear Anatech,
Thank you so much for your reply,
I was about to give up hope.
I stumbled across your reply by accident. I find this forum extrodinarily difficult to navigate around and highly frustrating.
Apparantly as I am not a full member I cant email you directly.
I will make a donation.
I too feel sad Nakamichi is disappearing. It must have been a brilliant place for you to work and I envy you.
I used to work for Akai UK supporting their pro audio samplers and multitrackers ( dinasaurs now) at the end of the `80s
Ive been in and out of all the top studios in London and have heard some absolutely staggering sound - not always my personal cup of tea- but but so clear it starts to scare you.
I have a 682zx cassette deck I had serviced years ago by Nakamichi in UK down in Brighton.
I could not believe the level of service.
They rang me- would I mind if I waited two weeks before work started on my machine as the 682 "guru " is on holiday ?
Fine I thought.
Later he rings me upwith a quote which was fine.
Then he asks me if I want everything else that is replacable, replaced with higher spec bits.
I ask why
He says that the technology the day it left the factory has been superceeded
I agree.
When I go down and pick it up I am told this machine will be fine for 10 years or so.
Then he pulls out a four sheet paper list of everything else replaced from pennies to a coulpe of quid.
I could not believe the sound difference- absolutely staggering.
Everything tightened up especially the bottom end.
Very nice people indeed - and my 682zx still sounds just as good.
I will follow all your advice and let you know how I get on.
Thank you once again
Chris
Dear Anatech,
Thank you so much for your reply,
I was about to give up hope.
I stumbled across your reply by accident. I find this forum extrodinarily difficult to navigate around and highly frustrating.
Apparantly as I am not a full member I cant email you directly.
I will make a donation.
I too feel sad Nakamichi is disappearing. It must have been a brilliant place for you to work and I envy you.
I used to work for Akai UK supporting their pro audio samplers and multitrackers ( dinasaurs now) at the end of the `80s
Ive been in and out of all the top studios in London and have heard some absolutely staggering sound - not always my personal cup of tea- but but so clear it starts to scare you.
I have a 682zx cassette deck I had serviced years ago by Nakamichi in UK down in Brighton.
I could not believe the level of service.
They rang me- would I mind if I waited two weeks before work started on my machine as the 682 "guru " is on holiday ?
Fine I thought.
Later he rings me upwith a quote which was fine.
Then he asks me if I want everything else that is replacable, replaced with higher spec bits.
I ask why
He says that the technology the day it left the factory has been superceeded
I agree.
When I go down and pick it up I am told this machine will be fine for 10 years or so.
Then he pulls out a four sheet paper list of everything else replaced from pennies to a coulpe of quid.
I could not believe the sound difference- absolutely staggering.
Everything tightened up especially the bottom end.
Very nice people indeed - and my 682zx still sounds just as good.
I will follow all your advice and let you know how I get on.
Thank you once again
Chris
Hi Chris,
Yes, a proper service and calibration will do wonders for a Nakamichi cassette deck. Doing a great job is as simple as following the instructions in the manual. Most people don't.
Those old VCR based multitrack machines didn't like to be moved or vibrated! I looked at doing these and backed out. We serviced the Tascam DA-88 format machines. Semi-pro customers could be a handful! Give me a real reel to reel any day (Studer). The upper Tascam machines were okay, but you adjusted everything to get them aligned mechanically. With Studer and Revox, you just replaced the worn parts. Much less shimming!
SO let me know how you make out with your CD.
Make sure your mail notifications are set to "on". You will get a link to your thread. You are now a full member, so the email system will work now.
-Chris
Yes, a proper service and calibration will do wonders for a Nakamichi cassette deck. Doing a great job is as simple as following the instructions in the manual. Most people don't.
Those old VCR based multitrack machines didn't like to be moved or vibrated! I looked at doing these and backed out. We serviced the Tascam DA-88 format machines. Semi-pro customers could be a handful! Give me a real reel to reel any day (Studer). The upper Tascam machines were okay, but you adjusted everything to get them aligned mechanically. With Studer and Revox, you just replaced the worn parts. Much less shimming!
SO let me know how you make out with your CD.
Make sure your mail notifications are set to "on". You will get a link to your thread. You are now a full member, so the email system will work now.
-Chris
OM5 fix attempt - anatech
Dear Chris,
I will be starting your recomendations on Saturday.
Week days my head is too caved in ( I work in I.T. now)
I should explain that at Akai I was a software bod - user support hotline.
I did take stuff to bits with the hardware guy who was a genius.
The nearest I got, was blowing EPROMS which held the various operating systems.
All the stuff I supported was digital direct to disc stuff.
There was some "tape gear" (digital ish) in the studio there, but was more of a museum piece than anything else.
Have made a donation.
Will let you know how I get on next week.Thanks again.
Chris
Dear Chris,
I will be starting your recomendations on Saturday.
Week days my head is too caved in ( I work in I.T. now)
I should explain that at Akai I was a software bod - user support hotline.
I did take stuff to bits with the hardware guy who was a genius.
The nearest I got, was blowing EPROMS which held the various operating systems.
All the stuff I supported was digital direct to disc stuff.
There was some "tape gear" (digital ish) in the studio there, but was more of a museum piece than anything else.
Have made a donation.
Will let you know how I get on next week.Thanks again.
Chris
Hi guys,
I have a similar problem to one of those stated here however, my problem is with my OMS-5. Like the guy with the OMS-4, when I stick a cd in I can hear the motor spinning the CD (And see it when I took the top off) but it won't play anything and will eject the disk after a few seconds. I'm handy with DIY but I've never really touched any electronics before so when I open up my player and try look for the feed belt I can't really find it. I'm hoping it's a problem with this and not the laser (My father replaced the laser once already when it used to be his and the parts are now unavailable here in Hawai'i) but any help would be greatly appreciated. Thanks in advance!
-David
I have a similar problem to one of those stated here however, my problem is with my OMS-5. Like the guy with the OMS-4, when I stick a cd in I can hear the motor spinning the CD (And see it when I took the top off) but it won't play anything and will eject the disk after a few seconds. I'm handy with DIY but I've never really touched any electronics before so when I open up my player and try look for the feed belt I can't really find it. I'm hoping it's a problem with this and not the laser (My father replaced the laser once already when it used to be his and the parts are now unavailable here in Hawai'i) but any help would be greatly appreciated. Thanks in advance!
-David
Hi David,
The feed belt is underneath the transport, on the bottom.
-Chris
The feed belt is underneath the transport, on the bottom.
I am really hoping he was trained by Nakamichi on how to set this unit up. He should have the original service manual, with out which, there is zero hope of getting it running even close to properly. Replacing the head by unscrewing the old one and installint the new one isn't even close to correct. This head is completely adjustable mechanically. Margin for error is very small. Then you do the electrical stuff. A god 'scope and real test CDs are required. Philips 5A for starters.
-Chris
Hi Chris,
Thanks for the help! Hopefully I'll be able to find it when I open it up again. About the laser, my dad didn't actually replace it himself but he payed the Nakamichi repair center here on Oahu (When they were still here) to replace the laser. He said it cost him about $500 back in the late 80s so I'm really hoping it hasn't malfunctioned again. The cd doesn't spin excessively fast when reading though, so I'm not too hopeful that it's just a feed belt problem.
-David
Thanks for the help! Hopefully I'll be able to find it when I open it up again. About the laser, my dad didn't actually replace it himself but he payed the Nakamichi repair center here on Oahu (When they were still here) to replace the laser. He said it cost him about $500 back in the late 80s so I'm really hoping it hasn't malfunctioned again. The cd doesn't spin excessively fast when reading though, so I'm not too hopeful that it's just a feed belt problem.
-David
Hi Folks,
btw, has anyone an idea, where to find replacement belts for those being used in the Naks OMS-5EII/7EII?
The lenght is 5.4 cm, as far as I remember. I once checked all available catalogues with a technician here in Germany, looks like those lenghts are not produced anymore...
All the best,
Salar
btw, has anyone an idea, where to find replacement belts for those being used in the Naks OMS-5EII/7EII?
The lenght is 5.4 cm, as far as I remember. I once checked all available catalogues with a technician here in Germany, looks like those lenghts are not produced anymore...
All the best,
Salar
Hi,
Sorry to bring back an old thread, but I have an OMS-5A II, I'm having similar symptoms to the ones listed in the first couple posts, and I'm not so sure about whether I want to mess with a CD player on my own. I've built a bunch of speaker boxes, reconed woofers, and redone crossovers and such, but when it comes to anything with a laser, I'd rather trust a pro.
Anatech, or anyone else - can you recommend someone I could send it to in the US, preferably in the southwest? Is it even worth it, or should I just buy something else?
Sorry to bring back an old thread, but I have an OMS-5A II, I'm having similar symptoms to the ones listed in the first couple posts, and I'm not so sure about whether I want to mess with a CD player on my own. I've built a bunch of speaker boxes, reconed woofers, and redone crossovers and such, but when it comes to anything with a laser, I'd rather trust a pro.
Anatech, or anyone else - can you recommend someone I could send it to in the US, preferably in the southwest? Is it even worth it, or should I just buy something else?
Hi Izmarkie,
you´ve got mail...
And here it comes. My Nakamichi OMS-5EII / 7EII alignement adventure!
But for those, who do not want to read the entire post, one question:
Got my Nak into ball park, but it will only play scratched CD´s perfectly about ONE HOUR OR MORE after being powered up. Any Ideas on that? Some old transistor in the servo circuit? I could have the Nak being powerded up the whole day, but hey, seriously, these are not the times for wasting energy any more...
Now the alignment story:
I have a two test CD´s for this purpose, a perfectly manufactured YEDS-18 test CD from Sony - but in fact, any other well manufactured CD will do the same.
For scratches, I use Digital Recordings "CD-Check".
It has black lines printed on the disc surface, ranging from 0.3mm up to 1,5 mm for testing the error correction, divided into four check levels.
The third CD is an old one from Keith Jarrett. It has a small spot on the aluminium layer, (no scratches on the disc surface) about 0,5mm, maybe a scratch from the label side.
The Nak did not even manage to play errors of about 0.3 mm on CD - Check (which btw delivers a very clean eyepattern, it seem to be very reflective, maybe because it is gold plated). The Nak also hang on the Jarrett recording. The laser is almost brand new, I swapped it two years ago.
But my other player from Sony manages to play scratches on CD-Check of about 1mm without any clicks, as well as the Jarrett recording. Because four lines are printed on CD-Check in an angle of 90 degrees, they in fact sum up to an error/gap of 4mm!!!
A friend of mine is developing a DAC based on the PCM 1704, which i will probably built into my Nak.
Because of this and because i was so frustrated about the Naks bad performance, I decided to give other electronics a try.
Because I have already built a clock from Tentlabs into my Nak, I started to look for a Philips based transport clocked with 16.9344 Mhz.
Got a cheapish player CD 753 with CDM12.1 from ebay and already drew plans for building this transport into the Nak - anatech would kill me for that!!!
But you can find the CDM-12 in almost any philips based player, even in High-End machines, lasers are easy to get, so wanted to check this out.
Unpacked the Phillips, (2 kg of plastic, the Nak weights 10 kg) played CD-Check, again no problems with scratches up to 4mm .
Played the Jarrett recording, (0.5mm on the aluminium layer) and the dammn Philips hang!!!
Now it looked like the Nak was not as rusty as it seemed. Maybe, the Sony´s and Philips optics have another focal lenght, in order to blur out scratches more easily?
I then experimented with the mechanics.
The disc motor could have been worn out. I bought a new one (Mabuchi RF-300T-11400).
But the shaft was too long. I did not want to take the risk in cutting it down, bought a bronce bearing and asked a mechanic to mill an aluminium spacer for the motor to house the bearing and shaft.
In fact, this did not seem to have any effect, but well, this construction should last forever - at least until the brushes of the motor fail...
BTW table height should be 4.5mm, measured from the top of the motor ( a brass spacer is originally fixed on it) to the bottom of the disc table.
Now the electrical alignment:
Alignment according to the service manual is only the first step. The second step is to look at the eyepattern. (Thanks anatech!)
One example:
According to the service manual, you trim focus offset by observing DC level on a certain test pin while playing a disc. You then stop playing and raise or lower the level until there is no change in play/stop mode.
But you will still get a clearer eypattern by turning the trimmer a bit more clockwise. The sweet spot is just before the eyepattern reaches the highest amplitude - and is the clearest. But according to the manual, focus is now far off, but my Nak works better now.
The same with E-F balance. When i try to align according to the service manual, I get a very noisy and bouncing signal in test mode wihich is not easy to observe.
But a workaround is to take a CD with long tracks and simply jump/skip between the tracks while observing E_F. It is now a relatively clear sinewave until the laser has reached the next/previous track and goes back to play mode. This wave should be trimmed while skipping until it crosses 0 V symmetrically.
I then took a CD with small clicks/ errors (i.e the Jarret recording) and fine tuned E-F until the cd was played without errors. In my case, this really meant turning the trimmer in fractions of a millimeter.
Now everything works perfect, I but as I stated, I get annoyed by the fact, that the Nak has to warm up for more than an hour until it performs best and I would like to find the cause for this.
Another backdraw was the additiona bearing for the disc motor . It starts to "sing" at low speeds, sounds almost like a testtone.
I later found out, that the clamper has some play. This is normal, but I fixed the clamper by placing a small brass rivet in the center hole of the clamper. The rivet sits now very tight on the motor shaft when a CD is inserted the clamper is more centered than before. I also removed the rubber cover from the clamper. With this lighter and centered clamper, the bearing runs silent now.
End of story,
all the best,
Sal
you´ve got mail...
And here it comes. My Nakamichi OMS-5EII / 7EII alignement adventure!
But for those, who do not want to read the entire post, one question:
Got my Nak into ball park, but it will only play scratched CD´s perfectly about ONE HOUR OR MORE after being powered up. Any Ideas on that? Some old transistor in the servo circuit? I could have the Nak being powerded up the whole day, but hey, seriously, these are not the times for wasting energy any more...
Now the alignment story:
I have a two test CD´s for this purpose, a perfectly manufactured YEDS-18 test CD from Sony - but in fact, any other well manufactured CD will do the same.
For scratches, I use Digital Recordings "CD-Check".
It has black lines printed on the disc surface, ranging from 0.3mm up to 1,5 mm for testing the error correction, divided into four check levels.
The third CD is an old one from Keith Jarrett. It has a small spot on the aluminium layer, (no scratches on the disc surface) about 0,5mm, maybe a scratch from the label side.
The Nak did not even manage to play errors of about 0.3 mm on CD - Check (which btw delivers a very clean eyepattern, it seem to be very reflective, maybe because it is gold plated). The Nak also hang on the Jarrett recording. The laser is almost brand new, I swapped it two years ago.
But my other player from Sony manages to play scratches on CD-Check of about 1mm without any clicks, as well as the Jarrett recording. Because four lines are printed on CD-Check in an angle of 90 degrees, they in fact sum up to an error/gap of 4mm!!!
A friend of mine is developing a DAC based on the PCM 1704, which i will probably built into my Nak.
Because of this and because i was so frustrated about the Naks bad performance, I decided to give other electronics a try.
Because I have already built a clock from Tentlabs into my Nak, I started to look for a Philips based transport clocked with 16.9344 Mhz.
Got a cheapish player CD 753 with CDM12.1 from ebay and already drew plans for building this transport into the Nak - anatech would kill me for that!!!
But you can find the CDM-12 in almost any philips based player, even in High-End machines, lasers are easy to get, so wanted to check this out.
Unpacked the Phillips, (2 kg of plastic, the Nak weights 10 kg) played CD-Check, again no problems with scratches up to 4mm .
Played the Jarrett recording, (0.5mm on the aluminium layer) and the dammn Philips hang!!!
Now it looked like the Nak was not as rusty as it seemed. Maybe, the Sony´s and Philips optics have another focal lenght, in order to blur out scratches more easily?
I then experimented with the mechanics.
The disc motor could have been worn out. I bought a new one (Mabuchi RF-300T-11400).
But the shaft was too long. I did not want to take the risk in cutting it down, bought a bronce bearing and asked a mechanic to mill an aluminium spacer for the motor to house the bearing and shaft.
In fact, this did not seem to have any effect, but well, this construction should last forever - at least until the brushes of the motor fail...
BTW table height should be 4.5mm, measured from the top of the motor ( a brass spacer is originally fixed on it) to the bottom of the disc table.
Now the electrical alignment:
Alignment according to the service manual is only the first step. The second step is to look at the eyepattern. (Thanks anatech!)
One example:
According to the service manual, you trim focus offset by observing DC level on a certain test pin while playing a disc. You then stop playing and raise or lower the level until there is no change in play/stop mode.
But you will still get a clearer eypattern by turning the trimmer a bit more clockwise. The sweet spot is just before the eyepattern reaches the highest amplitude - and is the clearest. But according to the manual, focus is now far off, but my Nak works better now.
The same with E-F balance. When i try to align according to the service manual, I get a very noisy and bouncing signal in test mode wihich is not easy to observe.
But a workaround is to take a CD with long tracks and simply jump/skip between the tracks while observing E_F. It is now a relatively clear sinewave until the laser has reached the next/previous track and goes back to play mode. This wave should be trimmed while skipping until it crosses 0 V symmetrically.
I then took a CD with small clicks/ errors (i.e the Jarret recording) and fine tuned E-F until the cd was played without errors. In my case, this really meant turning the trimmer in fractions of a millimeter.
Now everything works perfect, I but as I stated, I get annoyed by the fact, that the Nak has to warm up for more than an hour until it performs best and I would like to find the cause for this.
Another backdraw was the additiona bearing for the disc motor . It starts to "sing" at low speeds, sounds almost like a testtone.
I later found out, that the clamper has some play. This is normal, but I fixed the clamper by placing a small brass rivet in the center hole of the clamper. The rivet sits now very tight on the motor shaft when a CD is inserted the clamper is more centered than before. I also removed the rubber cover from the clamper. With this lighter and centered clamper, the bearing runs silent now.
End of story,
all the best,
Sal
Hi Salar,
And you now have a technician's touch. That is what separates the good techs from the great techs. The bad ones don't even read the manual.
Glad to hear you have it settled. It does sound like your disc table height is off a little though.
Hi izmarkie,
Look for a well regarded audio service shop or a semi-retired good technician working out of home. You need a patient, careful guy. An ex-Nakamichi tech might be a good bet. TV shops are probably not what you want, they can be destructive. Usually are on audio gear.
-Chris
And you now have a technician's touch. That is what separates the good techs from the great techs. The bad ones don't even read the manual.
Glad to hear you have it settled. It does sound like your disc table height is off a little though.
Hi izmarkie,
Look for a well regarded audio service shop or a semi-retired good technician working out of home. You need a patient, careful guy. An ex-Nakamichi tech might be a good bet. TV shops are probably not what you want, they can be destructive. Usually are on audio gear.
-Chris