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Nakamichi MusicBank MB-10 mods

linuxguru

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Joined
Feb 1, 2010
Messages
575
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Location
Chennai
The Nakamichi MB-10 is a 5-CD, slot-loading CD changer in the same form factor
as many single-CD players, and has an excellent 24-bit, 96 kHz DAC (AD1855) and
a high-quality build as well as electronics. Its only weakness (if any) lies in the
analog output stage, which is already very good, but can be improved a bit without
significant expense. Here I'm documenting all my modifications to the electronics,
mainly in the signal path:

(Note: Nakamichi uses very good shielding in the form of a metal shield below the solder
side of the PCB, which is secured by double-sided foam standoffs and soldered to the
PCB ground with tubular ceramic caps at various locations on the periphery. It's easy to
desolder 1 lead of each of the tubular ceramic caps, but be careful not to break them off
since the leads are delicate. The foam standoffs are firmly stuck to the shield, but the
glue can be softened by heating with a soldering iron on the metal shield, and the shield
can then be gently peeled off. After the upgrades, reverse the process to re-install the
shield to the PCB. It's time-consuming and delicate, so take care to do *all* the component
replacements in one shot before reattaching the shield. Also check for dry solders and
annular fractures at all the connectors, and reflow the solder with fresh solder if needed.
This is particularly important at the RCA output and Coax digital output connectors JK300
and JK601, respectively.)

Level 1:

1. IC301L, IC301R: Orig. JRC2114 unsoldered and DIP8 sockets installed. Socket pins
have to be bent outwards by about 0.5mm in both directions to fit the PCB holes. Install
your favourite dual DIP8 opamps here. I used 4x THS4041 on 2x Sjostrom Type-C 2x
SOIC8 single to DIP8 adapters. Upon reflection, LME49990 would be the opamp of
choice here.

2. C317L, C317R: Orig. Nichicon VR 22uF/16V replaced with Wima 3.3uF/50V MKS2XL.

3. C754, C755: Orig. NCC SMG 220uF/10V replaced with Panasonic FM 220uF/25V.

Level 1 mods are the only required mods, but if you can't leave well enough alone,
here are the Level 2 mods:

4. C753: Orig. Nichicon VR 1000uF/10V replaced with Rubycon YXG 1000uF/16V.

5. C100, C106 (DAC rail bypasses): Orig. NCC SMG 220uF/10V replaced with Panasonic
NHG 220uF/35V (lower voltage ratings are fine too).

6. C05 (Main PSU filter cap): Orig. Jamicon SK 2200uF/25V replaced with Elna RFO
3300uF/25V (just happened to have it on hand - 2200uF should be fine).

7. C07: Orig. Nichicon VR 220uF/16V replaced with Panasonic NHG 220uF/35V (lower
voltage rating should be fine).

8. (Designation obscured by glue, may be C06): Nichicon VR 1000uF/25V (I left it alone,
since it was glued on both sides and looked OK).

Headphone output section (optional, only required if you want to use the onboard
headphone amplifier):

9. C203R, C203L: Orig. Nichicon VR 1uF/50V replaced with Wima MKS2XL 3.3uF/50V
(lower values should be fine as well).

10. C202L, C202R: Orig. Nichicon VR 330uF/10V replaced with Rubycon ZLG 470uF/25V
(this is in the output signal path, so it's good to have a low ESR, low DF capacitor here).

11. C205: Orig. NCC SMG 220uF/10V replaced with Panasonic FM 220uF/25V.

I stopped my modification exercise there, since it had probably reached my point of
diminishing returns. If you want to go further, you can populate connector CN502 to get
access to the digital audio signals, which can be fed to a separate daughter-card with a
modern 24/192 DAC like the ES9023. I personally don't think it's worth the effort for a
20-year old Redbook audio CD-P like the MB-10, but YMMV. The transport and clock-
recovery digital audio/clock recovery sections seem to be very robust, reliable and clean.
 
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Tanoj

Active Member
Joined
Jul 6, 2011
Messages
512
Points
43
Location
Bangalore
I have same CDP, i love the sound of this CDP, although the Display got burnt and i am searching for its replacement,
the only problem w.r.t sound quality is one of the channel is weaker than other, can you help ?
 
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