I expect this radio to be a long term project that will take me years to complete. A little background info first.

I am rebuilding a 1971 Datsun 510 wagon. I have an Datsun AM/FM radio that I want to gut and fill with modern components. I want modern function with vintage appearance.

My goals for this radio:

Bluetooth and Aux 3.5mm jack inputs (minimum)
4 speaker output with Volume, Fader, Balance, Treble, Mid, and Bass controls
Internal Amp
Digital screen hiding incognito behind the original faceplate.
All of this contained inside the radio housing.

Here are some other things I've found that have much of what I am trying to build.

80s style radio for classic Celica - http://www.retrojdm.com/ArduinoCarStereo.asp

Joe's Classic Car Radios - http://www.joesclassiccarradio.com/addons.html

Here's a video showing some of what his radios do

The Plan:
Obtain a cheap Bluetooth/aux/other stuff module like this one -
and then cut the outputs and send them to a 4 speaker sound controller before they reach the sound chip on the Bluetooth module
then to an internal amp
remount the screen in my radio housing
Let cheap Bluetooth module control the inputs like normal for it
Let Arduino control Bluetooth module buttons and control sound controller
use extensions to put aux (and other inputs?) where I want them in the car

What I've done so far:

I spent a great deal of time looking around for front/rear fader capable sound boards built for Arduino. I was not able to find anything. I also couldn't find anything with the 3 tone control I was hoping to get from the radio. So I turned to my garage to find what I thought would work. I disassembled a radio/cd player from a 2003 Mazda Protege5 that I have had sitting in there for quite some time. I knew that this radio was capable of the various sound controls I wanted. I broke the radio down until all I had left was the main board.

The main sound control chip on the board is marked M62490FP. Here's a link to the datasheet.
http://www.alldatasheet.com/datasheet-pdf/pdf/1341/MITSUBISHI/M62490FP.html

That chip outputs the audio signals to a 35W per channel amp. I plan to retain that amp as well. I did keep the heat sink and will integrate it in to the Datsun radio housing.

The amp is an AN7555Z. Here's the datasheet.
https://industrial.panasonic.com/content/data/SC/ds/ds4/AN7555Z_E_discon.pdf

The amp I have totally figured out. But there are a few pins on the M62 that I'm struggling with. Pins 10 and 27 say "Outside Harmonic Parts for MID". As far as my skills take me, it appears that the op amps for the bass and the treble are present in the IC, but the mid range has been sent out to another chip. When I follow those lines to the other chip, I cannot figure out what is going on.

Chip number three, somehow linked to MID controls is marked with a Mitsubishi emblem, 5228, and then below that, 22H2. It has 14 pins. the only chip from Mitsubishi I can find marked 5228 is the M5228P. It's a 14 pin quad op amp chip so it seems right. But when I try to match what I see on my board to what the pinout for the chip shows, nothing makes any sense. Here's the datasheet.
http://datasheet.octopart.com/M5228P-Mitsubishi-datasheet-105375.pdf

I can trace pin 10 from M62 to pin 14 (output 4) on the 5228. But pins 1, 2, and 3 on the 5228 all seem to be connected to the same tracer. Pins 4 and 5 also seem to be connected to a different single tracer. I'm not seeing any variable resistors or potentiometers to control the output for the mids either. So I have absolutely no idea what the 5228 is doing or how its really connected.

Can you help me understand the 5228s connections? do I have wrong datasheet? Should I just replace the 5228 with a different chip? If I drop it, do I just loose mid control or does it do more damage than that?

Is there another, better way to achieve my goals without sacrificing them?

 

I had planned to edit my first post to include some extra pics but it won't let me edit it. So i apologize for repeating myself below, but there is additional info included.

I expect this radio to be a long term project that will take me years to complete. A little background info first.

I am rebuilding a 1971 Datsun 510 wagon. I have an Datsun AM/FM radio that I want to gut and fill with modern components. I want modern function with vintage appearance.

My goals for this radio:

Bluetooth and Aux 3.5mm jack inputs (minimum)
4 speaker output with Volume, Fader, Balance, Treble, Mid, and Bass controls
Internal Amp
Digital screen hiding incognito behind the original faceplate.
All of this contained inside the radio housing.

Here are some other things I've found that have much of what I am trying to build.

80s style radio for classic Celica - http://www.retrojdm.com/ArduinoCarStereo.asp

Joe's Classic Car Radios - http://www.joesclassiccarradio.com/addons.html

Here's a video showing some of what his radios do

The Plan:
Obtain a cheap Bluetooth/aux/other stuff module like this one -

and then cut the outputs and send them to a 4 speaker sound controller before they reach the sound chip on the Bluetooth module
then to an internal amp
remount the screen in my radio housing
Let cheap Bluetooth module control the inputs like normal for it
Let Arduino control Bluetooth module buttons and control sound controller
use extensions to put aux (and other inputs?) where I want them in the car

What I've done so far:

I spent a great deal of time looking around for front/rear fader capable sound boards built for Arduino. I was not able to find anything. I also couldn't find anything with the 3 tone control I was hoping to get from the radio. So I turned to my garage to find what I thought would work. I disassembled a radio/cd player from a 2003 Mazda Protege5 that I have had sitting in there for quite some time. I knew that this radio was capable of the various sound controls I wanted. I broke the radio down until all I had left was the main board.



The main sound control chip on the board is marked M62490FP. Here's a link to the datasheet.
http://www.alldatasheet.com/datasheet-pdf/pdf/1341/MITSUBISHI/M62490FP.html

And a pin diagram



That chip outputs the audio signals to a 35W per channel amp. I plan to retain that amp as well. I did keep the heat sink and will integrate it in to the Datsun radio housing.

The amp is an AN7555Z. Here's the datasheet.
https://industrial.panasonic.com/content/data/SC/ds/ds4/AN7555Z_E_discon.pdf


The amp I have totally figured out. But there are a few pins on the M62 that I'm struggling with. Pins 10 and 27 say "Outside Harmonic Parts for MID". As far as my skills take me, it appears that the op amps for the bass and the treble are present in the IC, but the mid range has been sent out to another chip. When I follow those lines to the other chip, I cannot figure out what is going on.

Chip number three, somehow linked to MID controls is marked with a Mitsubishi emblem, 5228, and then below that, 22H2. It has 14 pins. the only chip from Mitsubishi I can find marked 5228 is the M5228P. It's a 14 pin quad op amp chip so it seems right. But when I try to match what I see on my board to what the pinout for the chip shows, nothing makes any sense. Here's the datasheet.
http://datasheet.octopart.com/M5228P-Mitsubishi-datasheet-105375.pdf


I can trace pin 10 from M62 to pin 14 (output 4) on the 5228. But pins 1, 2, and 3 on the 5228 all seem to be connected to the same tracer. Pins 4 and 5 also seem to be connected to a different single tracer.



I'm not seeing any variable resistors or potentiometers to control the output for the mids either. So I have absolutely no idea what the 5228 is doing or how its really connected.

Can you help me understand the 5228s connections? do I have wrong datasheet? Should I just replace the 5228 with a different chip? If I drop it, do I just loose mid control or does it do more damage than that?

Is there another, better way to achieve my goals without sacrificing them?

And if anyone is interested, the car and radio in question.





Theres a whole long build thread if anyone would like to read it, just google "lockleaf z22 swapped goon".

 

The Harmonic Mid pins are for resistor /capacitor gain setting, i would use the original inputs to the chip pins2,3 and 34,35 and feed your Bluetooth in there, or use the Tape input.

 

So would it be best for Mids to simply choose a capacitor between the values used on bass and treble (0.068u for bass and 0.01u respectively) and/or figure out a resistor? Would that make the mids function?

 

According to the datasheet it says Resistor ladder, so i would use a preset resistor like a 10- 100k for starters, the capacitor is already on the exterior of the chip on pins 8,9,11.

 

Excellent. Thank you. That gives me something to work with.

Why would the original setup have the Mids going out to an op amp? Or is more likely that I traced it incorrectly on the board?

 

Possibly for Tape head frequency compensation, better to try and substitute the input signal for your Bluetooth, and see what happens, it may need more or less bass/treble with the external resistors.