In common with many MD units, the Aiwa remote sends commands by simply connecting different resistances across a couple of pins, which we will come to in a moment. I haven't tried connecting resistors across the inputs yet, just measured them with a meter.
Here is the pinout that we will use for the remote connector (the numbering
is my own):
The colour coding of the wires is as follows:
The AM-F65 remote signals commands with different resistances across
pins 1 and 2 on the connector. These were measured using a digital multimeter,
and are listed in the table below (column 2). The actual values
(column 3) were calculated by looking at the available resistors inside
the remote, and working out which resistor series (column 4) would be needed
to produce the value seen on the meter. Finally, the voltage between the
chassis (assumed to be at ground), and pin 1 was measured for each button
press (column 5), with the remote connected to the main unit.
|Play||1.6ohm||0||Short circuit pins 1+2||0v|
|nothing||-||-||Open circuit pins 1+2||2.811v|
Internally, the following resistors are used by the remote (you can
clearly see these on the scanned images of the PCB below):
1k2, 1k5, 2k, 2k7, 3k9, 6k8, 12k, 30k
Naturally, you could work this out properly by following all the tracks on the PCB. Fairly obviously, if you wanted to control the unit remotely, then it would be preferable to do so by chaining various resistances across the inputs. One way to do this digitally, from a PC for example, would be to use an analogue switch IC with a set of suitable resistors.
I include some pictures of the PCB from the remote, taken on both sides. These were produced by simply placing the PCB on a flatbed scanner and scanning at 600dpi, you can get the original images (which are quite large) by clicking on the smaller thumbnails.
Here is the underside of the PCB, you can see five push-buttons around the outside and the 'hold' switch on the bottom right hand side.
[click for larger image]Here is the top-side of the PCB, note the unused pads for LCD display and backlight:
[click for larger image]That's all the information I have to put up here so far, please contact me if you have anything you want to contribute. I don't plan to dismantle the main unit myself, it looks rather delicate and it's a bit expensive to risk damaging it :)
1. I have received an e-mail from Bryan Valencia (who has both AM-HX30 and AM-F65) which seems to suggest that the HX30 remote does not function with the F65 unit - apparently there is no drive for the LCD or backlight. This is bad news.
2. The table has been updated with (hopefully) more accurate resistance measurements taken with a digital multimeter (rather than the old 1950s analogue meter I used previously :), and now includes the voltage measured at pin 1 for the various commands - presumably the resistors on the remote form the lower leg of a potential-divider inside the main unit, which could be read using an ADC.
3. Several people have written to me and asked about the possibility of building a PC interface like this one. Although possible, it doesn't appear to be worthwhile since you cannot title from the remote.
Maintained by James Ward,
last updated 14/02/01.