When buying vintage CD player models in used condition from the upper price range, one should generally make sure that, electronic spare parts were used that were not made exclusively for the manufacturer and were also used in common brands and products.
This applies in particular to mask-programmed processors e. g. the MAB series from Philips with individual programming code (Txxx).
The "MD-1" transport seems to be therefore an example (but I am not absolutely sure).
According the youtube video under
(go to 0:11) the MAB 8441P T164 operates as servo processor, this type was also used in CD jukebox models from NSM and B&O Beocenter-Series - in the models 8000, 9000, 9300, 8500 and 9500.
This means, as replacement part still good available despite the age of 35 years, due the fact, that this program version "T164" was not exclusively made for Krell.
(according post #14 under
http://bbs.hifidiy.net/thread-540709-1-1.html
is the "T164" the professional version of the "T082" version used e. g. in Philips CD640/CD650)
But what about the display processor ?
The display itself, type "NSM4202A" which is probably in use - go to
https://www.diyaudio.com/community/...ement-for-philips-sony-cdm-transports.259790/
no issues should occur by ordering of replacements (is in the meantime no longer an issue due present remakes).
But the question is, which display processor is in use. Maybe the "MAB8441P T018" ?
If yes, this program version was also not exclusively made for Krell - go to Micromega's "SOLO" (first series) under
https://www.diyaudio.com/community/threads/micromega-solo-cd-player-help.191732/page-3
(images in post #52+53) and according
http://www.hifidiy.net/index.php?s=/home/marticle/detail/id/9630.html
and
http://bbs.hifidiy.net/thread-1048391-1-1.html
this user processor can be replace by the "MAB8441 T042"
If no, who know the type of the used display processor (in any cases also used for the operation instructions via RC) ?
Maybe the Krell model "CD-DSP" also haven't in the transport and display section processors exclusively made for Krell.
But all this I don't know exactly (unfortunately no images to find in tear-down condition of display PCBs for checking this).
Thank you very much for further advice.
Some URLs:
https://www.hifinews.com/content/space-age-cd
http://bbs.hifidiy.net/thread-1289393-1-1.html (very interesting details concerning first generations of Philips CDM mechanism and driver boards - unfortunately not in english)
https://www.octave-electronics.com/services/cdupgrade/cdupgrade2.shtml
https://audiodripper.jp/krell-md-cd-transport-restore
https://blog.naver.com/cellop2/100113477066
P.S.: Vasiltech published several years ago a CD-Player-DAC-Transport List with the used laser units (please note: URL corrupted or not adapted to current requirements).
If one had the same concerning the user processors, this would be very helpful in making a good choice when buying a used vintage CD player from the top class line.
This applies in particular to mask-programmed processors e. g. the MAB series from Philips with individual programming code (Txxx).
The "MD-1" transport seems to be therefore an example (but I am not absolutely sure).
According the youtube video under
This means, as replacement part still good available despite the age of 35 years, due the fact, that this program version "T164" was not exclusively made for Krell.
(according post #14 under
http://bbs.hifidiy.net/thread-540709-1-1.html
is the "T164" the professional version of the "T082" version used e. g. in Philips CD640/CD650)
But what about the display processor ?
The display itself, type "NSM4202A" which is probably in use - go to
https://www.diyaudio.com/community/...ement-for-philips-sony-cdm-transports.259790/
no issues should occur by ordering of replacements (is in the meantime no longer an issue due present remakes).
But the question is, which display processor is in use. Maybe the "MAB8441P T018" ?
If yes, this program version was also not exclusively made for Krell - go to Micromega's "SOLO" (first series) under
https://www.diyaudio.com/community/threads/micromega-solo-cd-player-help.191732/page-3
(images in post #52+53) and according
http://www.hifidiy.net/index.php?s=/home/marticle/detail/id/9630.html
and
http://bbs.hifidiy.net/thread-1048391-1-1.html
this user processor can be replace by the "MAB8441 T042"
If no, who know the type of the used display processor (in any cases also used for the operation instructions via RC) ?
Maybe the Krell model "CD-DSP" also haven't in the transport and display section processors exclusively made for Krell.
But all this I don't know exactly (unfortunately no images to find in tear-down condition of display PCBs for checking this).
Thank you very much for further advice.
Some URLs:
https://www.hifinews.com/content/space-age-cd
http://bbs.hifidiy.net/thread-1289393-1-1.html (very interesting details concerning first generations of Philips CDM mechanism and driver boards - unfortunately not in english)
https://www.octave-electronics.com/services/cdupgrade/cdupgrade2.shtml
https://audiodripper.jp/krell-md-cd-transport-restore
https://blog.naver.com/cellop2/100113477066
P.S.: Vasiltech published several years ago a CD-Player-DAC-Transport List with the used laser units (please note: URL corrupted or not adapted to current requirements).
If one had the same concerning the user processors, this would be very helpful in making a good choice when buying a used vintage CD player from the top class line.
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