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Old 14th August 2015, 01:57 PM   #1
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Default Mods cd-player Kenwood dp-7090

I purchased this wonderful machine in second hand market (ebay). black color.It is well built, nice looking device. simple. I made modification in the components and the final result is impressive.
Here below main characteristics of Kenwood dp-7090:
Digital converter: 8 x PCM1702, 20 bit
CD Mechanism: KSS-213B / KSS-213C
Download the service manual here:
KENWOOD DP-7090 Service Manual free download, schematics, eeprom, repair info for electronics

The interior is very tidy, accurate wiring and a lot of free space in the cabinet. But the original manufacturer designed the electronics in an interesting but bizarre way at the same time.

PROS: High-end DAC grade, dual mono design with 4 DAC x channel, Left channel and Right channel analog filters are with separate opamp, Power supply are regulated with high quality circuits, superb design of digital section, remote control with digital out level volume reg, very silent and accurate reading mechanism, headphone out with dedicated amp, superb layout engineering design.

CONS: several low quality components in the analog section which vanish the potential sound quality (see details below)

HOW to MODIFY the electronics to transform this Cdplayer into a high definition sounding machine:
- remove all transistors of the muting system Q33, 34,35,36,37,38 ; unsolder from pcb and throw them away
- replace all electrolytic capacitors used in the power supplies 22uF, 47uF and 100 uF with OSCONs Panasonic capacitors of same value
- remove 100pF ceramic capacitors C15, 17, 195, 197, 199, 201, 196, 198, 200, 202, 212, 213 unsolder from pcb and throw them away

- remove capacitors C87 and C88 ; unsolder them from PCB and solder a wire JUMPER in their place

- replace all NJM4580L OPAMP IC-19,20,21,22,23,24 with AUDIO Grade high res OPAM. I used LME49990, it is wonderful. Use an smd general purpose pcb as adaper, weld the opamp and solder pins. Attached the datasheet for your reference. Here you need some skills.. not an easy job for everybody

- replace all capacitors on OPamp filters with MKP polypropylene caps

- I deem that there is no benefit in changing the power transformer. The power supplies are so very well designed that I do not see any benefit , it will not give any effect.

ENJOY the sound of this fantastic machine!!
Attached Files
File Type: pdf NJM4580.pdf (165.9 KB, 8 views)
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