Help wanted: Factory radio aux/bluetooth mod retrofit 89-92

[Luis5.oh]

Before anything I already spent like 15 hours (no jokes) doing my research with few discoveries but not enough and NO I'DONT want to replace with a sh**ty aftermarket unit, I already have done that several times other cars and this one is in great condition, also I want to probe myself.

The radio is a base Cassette player with dolby and rev, same as 89-92 mustangs foxbodies, after a lot of research I found that IC601 is equivalent to a TDA3420 and works as the preamp of the tape player, after that Im lost, I wasn't able to find or tell if this radio has a commuter(like newer style radios have) to switch signals from AM/FM and the TAPE, I have the new style cheap bluetooth module already, I wasn't able to find a schematic for this radio. My goal is to replace AM trace with this, I don't mind losing AM since it doesn't work where I live and I do plan to use tape and FM.

Sorry for this too much text, hope I explained myself.

 

[RobbieD]

I wasn't able to find a schematic for this radio.

Welcome to TRS.

Sorry that I can't help you with the PCB mods that you want to make, but I do have the Ford audio repair manual for 1986.

It should cover the head unit that you're working on, and if you can give me an idea of the information or sections that you're looking for, I'd be glad to image it and post it.

For starters, this is the electrical schematic for IC601 and the AM section: (for "AM/FM Cassette Without Equalizer")

Just try to give me an idea of what you're needing; there's a ton of info in this manual (description text, block diagrams, voltage measuring tables, etc.).

 

[Luis5.oh]

Wow, I really appreciate your input! That pretty much explains the route that the L and R signals from tape go, they enter the IC601 through pin 7 and 9 and then go to the DOLBY IC651, I wonder where they go then, my goal is to intercept the AM signal so BT plays only with AM on and ignores FM and TAPE, just like @BlackBII did in this post https://www.therangerstation.com/forums/index.php?threads/blackbiis-white-ranger.138828/post-1604373

The other unknown IC's are: IC501, IC502 and IC851.

Many thanks, may god bless you!

 

[85_Ranger4x4]

@BlackBII

I put together a Retrosound radio for mine, looks kinda like the old base model radio that was factory to my truck but it has blueteeth, aux inputs and all that.

 

[RobbieD]

Wow, I really appreciate your input! That pretty much explains the route that the L and R signals from tape go, they enter the IC601 through pin 7 and 9 and then go to the DOLBY IC651, I wonder where they go then, my goal is to intercept the AM signal so BT plays only with AM on and ignores FM and TAPE, just like @BlackBII did in this post https://www.therangerstation.com/forums/index.php?threads/blackbiis-white-ranger.138828/post-1604373

The other unknown IC's are: IC501, IC502 and IC851.

Many thanks, may god bless you!

You're welcome, and I'm glad that it helped.

A pic of IC501, IC502 and IC851 is included here; hopefully you can zoom in to see enough detail.

Again, if there is any other information that you need out this manual, just ask, and tag me on the reply so that I'm sure to see it.

 

[Luis5.oh]

You're welcome, and I'm glad that it helped.

A pic of IC501, IC502 and IC851 is included here; hopefully you can zoom in to see enough detail.

Again, if there is any other information that you need out this manual, just ask, and tag me on the reply so that I'm sure to see it.

View attachment 127740

After I saw you reply I started to do some testing, Its not on you, that schematic is huge! It's hard to post and there is literally no digital version of it, I'll post my progress, it doesn't look like much but it took me several hours to know what ICs do.

Im pretty sure those all are the ICs in this radio with the exception of one under the board but I think it controls the LCD so it's not relevant I think. If you see I added some orange arrows, the ones with a "?" in the tip means I'm not sure that's the route they go, the ones with the checkbox im pretty sure they follow that route.
I couldn't confirm but I think IC851 is the one that ultimately feed the actual amplifiers, maybe the stereo decoder is the one I want to intercept, I can't see much but it think the AM and FM chips doesn't provide actual L and R speaker signal, but maybe the decoder is the one that does that job as in the last picture you posted it appears to have L and R outputs.

Sorry for too much text! I promise that if I solve this puzzle I'll post the "How to" to help other geek folks like me, reminds me of the old times when people used to post guides without wanting any reward, there are few guys that have solved this but WONT help me since they charge to get the service done and I don't blame them, work is work.

 

[RobbieD]

It will have to be later today, but I'll see if there's a description, flow chart or block diagram that shows how the L and R channels run.

The wiring schematic is huge; it's 10 joined sheets that unfold out of the book.

 

[BlackBII]

Man that was years ago. I did eventually add a 12-5v stepdown converter and powered the bluetooth module by the radio itself. But, I swapped in a touch screen unit a couple years ago; the factory amplifier in the stock radio just didn't have the power to drive the new kenwood speakers I put in, and I also wanted to run a small subwoofer behind the seat.

I remember working on this for many hours. Once I found the data sheet, it made it much easier. At one point, I had the radio hooked up to 12v with two speakers wired in, and I was prodding chip terminals with a audio signal to try to find where the AM inputs were.

The stereo you have there is different, so I am not sure I'll be much help here but I can help where I can

BlackBII's white ranger

New parking brake cables. These were a huge pain in the ass. Especially the front one. But, now I have a working parking brake so it was worth it.

www.therangerstation.com

 

[Luis5.oh]

Man that was years ago. I did eventually add a 12-5v stepdown converter and powered the bluetooth module by the radio itself. But, I swapped in a touch screen unit a couple years ago; the factory amplifier in the stock radio just didn't have the power to drive the new kenwood speakers I put in, and I also wanted to run a small subwoofer behind the seat.

I remember working on this for many hours. Once I found the data sheet, it made it much easier. At one point, I had the radio hooked up to 12v with two speakers wired in, and I was prodding chip terminals with a audio signal to try to find where the AM inputs were.

The stereo you have there is different, so I am not sure I'll be much help here but I can help where I can

BlackBII's white ranger

New parking brake cables. These were a huge pain in the ass. Especially the front one. But, now I have a working parking brake so it was worth it.

www.therangerstation.com

The 5v step-down is the easy part, I actually have a cheap small usb 5v adapter to cigarette port, so Im positive it has a 5v regulator inside, noise is a concern but I also have a few components that may help in that case, what I truly fear is this having no commuter like yours did that you just overwrite the AM signal, this one apparently has AM and FM in one line, that case I may need to make a small relay.
I recently upgraded the audio system of my 95GT with alpine stereo and discrete 400w amp hidden where the OE amp is, JBL component speakers and it sounds way better than wife's new car, however driving my 90 ranger all stock that I bought just to carry my mountain bike hits different.

 

[Luis5.oh]

It will have to be later today, but I'll see if there's a description, flow chart or block diagram that shows how the L and R channels run.

The wiring schematic is huge; it's 10 joined sheets that unfold out of the book.

That would be great, I wonder if the schematic defines what are the actual chip name for the ICs, I mean, I don't know if im missing something but the actual chip names on my radio won't pop anything on google to see the data sheet.

 

[Luis5.oh]

Made some progress, I connected L, R and G signals from bluetooth module to pin 4, 15 and 18 of IC851 (Active Tone) respectively.
Here is YouTube short video of demonstration
The sound is glitchy, it sounds worse than in the video, of course a the speaker is not enclosed but I noticed that when I turn the volume or bass to much the audio cuts for a few seconds. I noticed some people put capacitors in series with the signal, unsure if I should do it too.
My next move will be re-assembly the radio to test it on the truck.

 

[RobbieD]

@Luis5,oh , I've had a busier than expected day, but I'll be posting some images from the repair manual later tonight. I like your idea of using the AM function for the bluetooth, so I'm looking at posting anything that's related to the AM circuits in the unit.

Stay tuned!

 

[RobbieD]

I've got some images for you, and some comment.

It'll probably go much easier if I make several posts.

For openers, here's is the ICs as listed in the manual's parts list. This might get you farther in finding IC spec sheets.

Second, some "Precautions" in testing that jumped out at me, for you to be aware of as to not get tripped up.

I had to shrink the images. I hope that you'll be able to read them.

More to follow; bear with me.

 

[RobbieD]

"Same song, second verse. Ought to get better, but it's gonna get worse."

First of all, I have no idea what I'm doing here, but you sound to be a lot knowledgeable with board electronics.

Something that caught my attention, is the IC551 Muting Distribution seems to kind of control the show in these radios.

These pages caught my attention.

And

So . . . it seems to me, if you were wanting to interrupt the AM audio line signal, and, replace it with an added outside device, it would seem that it could be done between AM section IC201 and the Mute C551.

Another page; I *think* that "Mute Distribution IC501" is a typo, and should be "IC551".

More to follow . . .

 

[RobbieD]

This is the section of the HUGE schematic sheet that covers circuitry between IC201 and IC551. I have added some highlight to trace the AM audio circuit between them. Unfortunately, it turned out lo-res.

I could PM you a higher-res of this image, if you'd like it.
Interestingly, AM audio input is on two jumpered pins on IC551, because there's an option for AM stereo. If you could get a bluetooth signal in at this IC, it might be possible to have 2 channels for stereo, I'm thinking.

These two pages show the PCB layout, top and bottom, in case it's helpful.

One more post to follow . . .