Kenwood CP-C7 "Walkman" and Repair

I have been wanting an ultra-thin walkman for a while...preferably with Dolby c. So I found this Kenwood cp-c7 (technically not a walkman since it is not Sony). Bad cosmetic condition. But it does work... sort of. It has some serious battery corrosion.

To clean it, I have to open it up and that is not an easy task. The buttons are printed upon soft PCB films, which are stuck to the plastic frame by adhesive. The circuit board inside is thin and fragile. The worst part is that, after unscrewing all the screws, I still found myself unable to take out the board. I thought it was held together by double-sided tapes, so I tried to pry it open carefully, not aware that a solenoid was attached to both the PCB board and the mechanical frame. That did not end well. The solenoid was broken. Looking back to it, I should have tried harder tracking down the service manual.

So I had to rebuild the coil and add new soldering leads (and of course, clean up the corrosion inside the walkman also). The belt seemed fine with enough tension. Although this device is designed to run on a single gum stick battery, in practice, the w&f seems rather unstable when running on a gum stick, likely due to the lower voltage. So I use a 5V-to-1.5V converter, which ensures a constant voltage supply (it was later modded to run a single AA battery. Blackube in this case, which is rechargeable by USB).

It is working properly now. It has trouble with a few tapes (in terms of w&f) but works fine for most. Compared to my DDII, it has more treble but less bass. The bass is not as powerful and deep. Mechanical noise is kind of loud (needs more lubrication). I can also hear some motor buzzing noise during the quiet session of the music. I think it is probably due to old capacitors. Dolby c does work, but I haven’t had the best experience with it so far. A huge bummer is that the buttons aren't very responsive. Film buttons really aren't great.

Walkman archive puts the white model of cp-c7 on the list of the cute and stylish designed walkman. I think my particular device isn’t that impressive visually. This model is also mentioned in the “which walkman sounds the best” article since its design is based on the best Aiwa. Mine does sound decent. Wish I could do a better job in terms of repairing and refurbishing the device.

Update: I lubricated the device recently and the mechanical noise got a lot quieter. The device also ran faster so I had to reduce it to standard speed. Motor buzzing noise from headphone output was also reduced significantly.

Kenwood CP-C7 modded to run on an USB-rechargeable AA battery

CP-C7 running on a 5V-to-1.5V convertor

Working on CP-C7

You can see the film buttons at the bottom

Rebuild the blue solenoid

Comments

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