Beogram 4002 (5513) Remote Control: Now With a Professionally Made PCB

I redesigned the circuit board for the remote control receiver that I recently built for my Beogram 4002 (5513), and had a few manufactured by a professional PCB manufacturer. The boards came today, so I had to populate one of them right away and give it a spin in the Beogram...;-). Exciting!! I always love to see a new circuit board come together.

The main design changes were to put all components on the top side to ease the assembly process, and to move the ISP port out of the way of the fixture that holds the top aluminum panel. I also removed the reset button from the design and gave the keypad connector some more room. Furthermore, the location of the header that allows to directly plug the board into the keypad socket now protrudes from the main board area. This makes it much easier to plug it in, since one can now see next to the header pins and direct them into the proper female jacks on the keypad socket. This was difficult with the prototype. Here are a couple pictures of the assembled board. Front:

and back:

The large hole is for access to the screw that holds the main PCB of the Beogram. I am planning to give the receiver a 3D printed 'tray' to fix it in place with that screw, and to insulate it from the solder points of the board below. For now, this insulation is provided by a cut from a overhead transparency taped to the bottom of the board - not too pretty, but works. After populating the board the Atmega328p microcontroller needed to be programmed. I hooked the board up to a bench supply and connected the AVRISP MkII programmer and gave it some brain:

Now it was time to install the board. Here is a photo of the board plugged into the socket of the keypad connector. The connector itself is plugged into the socket on the board. This preserves the keyboard functionality.

This looks pretty nice now!...Perfect location of the IR receiver cable, too. I am looking forward to having the printed tray. This should make it fully plug-and-play. After reinstalling the panels the Beogram functioned identical to the prototype (as recently demonstrated in this YouTube video).

Hot Beolove..;-)!!

Beogram 4002: Apple Remote Controls All Functions of Turntable

I recently developed a remote control receiver that plugs into the keypad connector socket on the main circuit board of Beogram 4002 (5513 model) turntables. I have been testing it now for a few weeks, and it works very reliably. So it is time to post about it.

The implemented receiver board takes over the keypad without interfering with it, i.e. the Beogram can still be operated as usual via the keypad. I decided on using the latest Apple IR remote control that still comes with the Apple TV. I was attracted by its sleek aluminum surfaces, which match the 4002 style well. The sparseness of its buttons also almost perfectly matched the application at hand.

My main motivation for the development of the remote system was to preserve my perfectly restored keypad from wear and tear. In addition, I always thought the cueing function of these Beogram models could use a bit of improvement. For my taste the "<" and ">" buttons result in too slow cueing if one wants to skip a couple tracks, while using the "<<" and ">>" buttons requires quick action to stop the movement with either the "<" and ">" buttons or the tone arm up lift button. This makes it difficult to effectively place the arm at the start of a certain track.

The implementation of the remote control allowed me alleviate this issue by programming a dynamic cueing function that automatically switches to the higher cueing speed after ~2 seconds of pressing the cueing button, and that also automatically terminates when the button is released. This makes it much more straight forward to precisely hit the transition groove between two tracks.

I made a video demonstrating the remote control. It also shows some details about the implementation of the receiver board:

The remote board is based on the Atmega 328p microcontroller (aka "Arduino"), which receives its commands via an integrated 38 KHz IR receiver (IRM 3638). The board essentially 'imitates' the pressing of keys via transistor networks that make 100ms connections in lieu of the switches. Since this is fully parallel to the keyboard switches, they keep working in this scheme. Here are a few pictures of the setup:

Bottom side of the receiver board. Arduino controller and male header that plugs into the keypad socket of the Beogram main PCB can be seen. The small SMD parts are the transistors etc...:

 Top side of the board: The female header connects the original keypad connector:

This shows the board installed:

This shows the remote receiver as it peeks out from underneath the cabinet:

The next step of this project will be the design of a more professional board layout and get it manufactured instead of winging it with Fe-chloride, a laser printer and my wife's iron...;-). The issues with this prototype are for example that the in service programming port conflicts with the fixture that receives the standoffs of the top aluminum panel (hence the strip of plastic over it in the above pic - I was lucky that I could still install the panel...;-). Also the remote receiver connects a bit too far to the right, also interfering with this fixture...obviously, I did not consider its existence when I designed the prototype..;-). I also would like to have some more space for the keyboard cable, i.e. the female connector could be moved a bit further away.

In the meantime, back to my current restoration projects!