Need schematic and possible help with DELCO radio mod.

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dacflyer
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Need schematic and possible help with DELCO radio mod.

Post by dacflyer » Tue Feb 07, 2017 6:49 am

Need schematic and possible help with DELCO radio mod. "model 30015807" for Geo Metro.

i am wanting to modify the radio, take out the defunct tape deck and make it possible to flip a switch to make it go from radio to tape mode, and use the tape input as an AUX. input for a mp3 player or to connect phone to to play musik.. i had seen it done somewhere else before, but not with this model.
a schematic would help a lot.. i know i'll need to fool the tape reel sensors somehow..

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Externet
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Re: Need schematic and possible help with DELCO radio mod.

Post by Externet » Tue Feb 07, 2017 7:25 am

Done that, without schematic. Key is to compare various ICs in the stereo with their data sheets to find which one handles the audio path, usually obeying a microcontroller data to do the selection.
Manual band buttons/tape mode switches may input to a microcontroller, and the microcontroller tells the audio path IC to select which audio input.

Then probing you find which pins are L,R 'tape in' to the audio path selector IC. Hook up the new auxiliar L,R audio to those instead of the 'preamped tape head'. When tape button or tape mechanism is engaged, the audio selected will be 'Aux' from an added jack/cable for the player.

Can be as simple as a CD4052, or a dedicated audio industry IC.

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Re: Need schematic and possible help with DELCO radio mod.

Post by dacflyer » Wed Feb 08, 2017 7:09 am

my issue is also the reel sensors, and the mode switch on the tape deck,, the tape deck is not a simple one, it is one of them auto reverse units, the IC's on this unit are also covered in what looks like hot melt glue or epoxy.
there is 2 cables that goto the tape deck..
1st cable is white with 13 white wires and 1 black
2nd is a red cable with 6 reds and i white.
all that just for the tape deck..

other option i was looking at was the volume input.. looks like a single pot with SW. might be easier solution to try..
i hope it is not anything digital..

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Re: Need schematic and possible help with DELCO radio mod.

Post by dacflyer » Mon Feb 13, 2017 2:02 pm

no luck yet....

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Externet
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Re: Need schematic and possible help with DELCO radio mod.

Post by Externet » Thu Feb 16, 2017 11:06 am

Check if your stereo has the TEA6320 IC in it. That is the one mine uses. Its data sheet is available to do the hacking.

Inserting the auxiliar audio into the volume control input (at X) before the final amplifier could be simpler, using a cancelling stereo jack. I have obtained those proper 3mm jacks canibalizing defunct PC sound cards.

Selected audio ------X--------volume control--------final audio stage--------speakers

----> http://factoryradioservice.com/images/MVC-185S_LR_1.JPG

----> http://landroverforums.com/forum/discov ... nit-72682/
- Abolish the deciBel ! -

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dacflyer
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Re: Need schematic and possible help with DELCO radio mod.

Post by dacflyer » Thu Feb 16, 2017 6:11 pm

nope,, nothing like that in my radio.. all chips in this radio are house marked..

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Re: Need schematic and possible help with DELCO radio mod.

Post by haklesup » Fri Feb 24, 2017 1:56 pm

still, you should be able to find the nodes where the tape head amplifier leads into the source switch by touching the nodes and seeing when you hear a buzz in the speaker. it can't be too new and integrated, it has a tape deck for goodness sake.

Matching the impedance of that to your new sources is something that also needs attention or you will oversaturate and get hiss or under drive and get whispers. used radios are practically falling out of cars at pick and pull and show up on ebay regularly. What size hole in the dash do you need to fill?

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Re: Need schematic and possible help with DELCO radio mod.

Post by CeaSaR » Fri Feb 24, 2017 5:59 pm

The Geo Metro is either DIN, DIN and a half or Double DIN. They are too new for shaft and too old for "Infotainment". Hate to say it, but you could have purchased a new unit and a Scoshe install kit and been enjoying by now.

Can't you follow the tape head path? As for the other issues, use a "screw together" cassette and remove the tape from the reels. F the tape Ned's to be there, make a continuous loop of blank tape that will allow the reels Ro turn and the sensors sense the tape. Should be straight forward enough, one would think.

CeaSaR
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dacflyer
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Re: Need schematic and possible help with DELCO radio mod.

Post by dacflyer » Tue Feb 28, 2017 7:43 am

it is a double DIN and low on the console, just above the ashtray.. using a modern radio with a display screen is not feasible because of the viewing angle and such..

and the radio i got right now is missing the tape mechanism..
the radio that's actually in my car i have not removed yet, was trying to figure the donor radio out 1st.
it would help a lot if i was able to cross the IC's. i think i found it, but not sure.. the tone controls and volume go into the chip. but i can't make out the outputs yet.. digital output ?

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Re: Need schematic and possible help with DELCO radio mod.

Post by dacflyer » Thu Sep 28, 2017 2:51 pm

hi all, i am back on this project now.. it's been on the back burner a long time now..
anyway i been doing some more probing around the radio some today and i think i found the raw audio before the processors..
all the raw audio goes into 2 small transistors ( 1 for right and 1 for left i suspect ) then they proceed to a IC chip labeled as
( house marked )
16191250
ZP9KT9509 ( the chip is located near the power connector, there is no IC location number )

only thing is, i cannot find any data on the chip, the maker of the chip is marked "ST" microelectronics ?
it is some sort of audio control or processor chip. i'm looking for a pin out.
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haklesup
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Re: Need schematic and possible help with DELCO radio mod.

Post by haklesup » Thu Sep 28, 2017 3:39 pm

ST made lots of Amplifiers, most are in the TI product line now especially the D class amps but plenty of analog integrated amps too, usually in a SIP package with a Tab. Post a photo for our experienced eyes to see.

Once you identify the primary Amp chip, the app note circuit will probably be very close to part of the radio circuit.

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Re: Need schematic and possible help with DELCO radio mod.

Post by dacflyer » Fri Sep 29, 2017 8:12 am

it is not a amp. it is a SMT flat chip.. i didn't count the pins. if you want a pic, i'll post one when i get home this afternoon..

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haklesup
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Re: Need schematic and possible help with DELCO radio mod.

Post by haklesup » Fri Sep 29, 2017 10:54 am

D class amps usually take this package but most have a metal top heat spreader which may or may not have a heat sink on it.

For example

TDA7492 has no heat sink was developed by ST
http://www.st.com/content/st_com/en/pro ... a7492.html
http://www.ebay.com/itm/TDA7492P-50W-50 ... Swi8VZRIcF

TPA 3116 (usually has heatsink applied to the top surface, I found this image without)
http://www.ebay.com/itm/TPA3118-PBTL-Mo ... SwiqtZisbT

the TDA7498 http://www.st.com/en/audio-ics/tda7498.html

If the radio is more then 5 years old, it may be all analog, D class is relatively new. These 3 are common is todays designs with many boards on ebay

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dacflyer
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Re: Need schematic and possible help with DELCO radio mod.

Post by dacflyer » Mon Oct 02, 2017 5:10 am

well Saturday night i was bored, i took radio apart, and just probed around for a while.
i discovered that all the controls are digital controlled. (A/D) they all go into a 16 pin chip where they are digitally outputted. all controls are pots,
anyway i finally found some decent sounding audio.. probed some more and found good audio. so with this good audio i did some circuit surgery, i added in a switched 1/8" stereo jack, so that
the radio still plays,,but when you plug in your audio device ( my satellite radio ) it disconnects the fm radio audio and my audio is fed into the circuit..
this audio is somewhere before the audio controls ( volume tone etc ) bench tested it, it sounds great. i was done about 2am..lol
i just need to find me a belt now for the cassette deck now..

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Janitor Tzap
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Re: Need schematic and possible help with DELCO radio mod.

Post by Janitor Tzap » Tue Oct 03, 2017 11:20 am

Here's the 2006 PRB Belt Guide.
http://www.russellind.com/client/downlo ... t_XRef.pdf

Nice tinkering Dacflyer. :)

But couldn't you of just used one of these?
Image


Signed: Janitor Tzap

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