the home of the turntable

The Hacking Of AKAI AP-B21

tales from the tool shed

The Hacking Of AKAI AP-B21

Postby hal rockwell » 22 Jun 2012 20:59

I decided to liven up my interest in my turntable and my record collection by making it more user friendly.

First of all, fixing the cover hinges so I won't have to remove the cover entirely when playing records. The springs in the hinges broke the plastic overtime. I drilled through the hinges from side to side and inserted nails through them to hold the springs in place and covered the broken plastic with painted shapelock. I couldn't find replacement hinges anywhere.

Second, I integrated a complete phono preamp with its power supply within the turntable's chassis. This also required a power switch for the entire system because the amp's power supply is wired in parallel to the power input of the turntable and I didn't want it to be active all the time that the turntable is connected to the wall socket. My first attempt at wiring the amp in the chassis failed because it added a lot of electrostatic hum and interference. After some experimenting I found out that these interferences are caused due to faulty cable I used for wiring (speaker cable). I changed the cable to a musical instruments shielded cable and that fixed the hum problem completely.

Third, I bought a new belt on the web and it fixed the lag problem the turntable seemed to have with the old belt.

After downloading the service manual and completing the hacks and the setup, the turntable works better, takes less space on my desk and is much easier to connect to my powered speakers.

Image
The entire chassis view.

Image
The input and the output of the amp.

Image
The preamp and the power supply.

Image
The power switch.

Image
Preamp closeup.

Image
Power supply closeup.

Image
Rear Panel.

Image
Front Panel.

Image
The fixed hinge.
hal rockwell
junior member
 
Posts: 17
Joined: 19 May 2012 12:56

Israel

Re: The Hacking Of AKAI AP-B21

Postby midnightmayhem » 24 Jul 2012 05:41

That is awesome dude! Iv been thinking about doing that type of thing with an old radio turntable combo with an old ceramic cartridge. If i added a preamp like you have i could run a real cartridge!
Reworked Pioneer PL-50
Dual 1242
David Bogen AP-35
Custom hand built (by me) 12AU7A Preamp
2 Hammond Monoblock 6BQ5pp Converted to HI-FI
4 large advents
$9700 in cables alone LOL
midnightmayhem
member
 
Posts: 79
Images: 1
Joined: 11 May 2012 01:10

United States of America

Re: The Hacking Of AKAI AP-B21

Postby Blue Angel » 24 Jul 2012 11:33

Nice work!

I once had a Micro Seiki MB-18 into which I built a motorcycle battery and charger to run the deck off 12Vdc. I added a mechanical, solenoid-operated mono switch which had a pushbutton on top of the plinth, together with a red LED to show when mono was selected.

I then changed the pitch potentiometer to give me also 78rpm.

Your IEC socket is upside down, btw :lol:

Happy tinkering.

ba
"If you don't like my principles, I have others" - Groucho Marx
Blue Angel
contributor
 
Posts: 5852
Images: 241
Joined: 15 Aug 2005 20:15
Location: Cape Town, South Africa

South Africa (old)

Return to DIY


Design and Content © Vinyl Engine 2002-2013

faq | site policy | advertising | hifiengine