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October 07, 2022, 02:32:58 AM

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Maybe a bit off topic... Adding an aux input to a radio CD and tape player, boom

Started by Oooscar, March 10, 2022, 10:29:45 AM

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Oooscar

Hello all,

Maybe a bit off topic, but maybe you can give me some help...

I am trying to add an aux input to a boombox radio I have at home
I have not found the schematic of the main board, it's a MX-Onda
MX-MCP6428Mp3. So far, I don't want to use the tape player or the
CD player. I want to modify the circuit on the radio Mode.
It has an analog volumen pot with six pins, and the following ICs,
SA2111 is the radio IC, and NEC1316C is the power amp IC.
I can't see any sort of Jumper wire that would allow to connect an
stereo 3.5 female Jack with 'two poles' to keep the radio on, but
connecting an aux instead of the radio. Everything seems printed
on the board.

I have tried to connect directly my smartphone to one of the inputs
of the NEC1316C ic, but the sound is barely heard, It's like the IC
ignores that signal, and the radio signal keeps there. The volume pot
does not improve the situation. Something is going on, but I am lost.

Anyone here has any clue how can I make It if it's possible?

Thank you very much for your attention. Thanks for stopping by.

Cheers



joecool85

To be clear, you are trying to keep the radio, CD, and tape functionality and add an aux input?
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

Oooscar

Yes, exactly. Just modding the radio circuit. Actually, later I checked
the SA211 ic, the radio IC, and I looked at the tracks of its outputs.
I think there are some jumpers/resistors along those tracks that I can
open, maybe, and connect there the 3.5 female Jack stereo, with
double pole. I Will try that, similar to this example

http://www.outosoft.com.au/blog/files/boombox-aux-in-part1.html

Cheers

joecool85

Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

Jazz P Bass

I would 'cut' the traces coming out of the SA21111 at pin 13 (R OUT) & pin 14 (L OUT).
Solder in your aux input after the cut in the traces.

Oooscar

Quote from: Jazz P Bass on March 11, 2022, 12:04:57 PM
I would 'cut' the traces coming out of the SA21111 at pin 13 (R OUT) & pin 14 (L OUT).
Solder in your aux input after the cut in the traces.

Heyy, thanks a lot for your reply... That's what I did, yes... And It works... I cut the jumpers on the output tracks, and added a female 3.5 stereo Jack with five pins, so that I can listen the radio and also an aux input...

joecool85

Quote from: Oooscar on March 13, 2022, 08:43:31 AM
Heyy, thanks a lot for your reply... That's what I did, yes... And It works... I cut the jumpers on the output tracks, and added a female 3.5 stereo Jack with five pins, so that I can listen the radio and also an aux input...

Good job, and great choice using a switching jack so you can keep the radio as well!
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com