Mitsubishi W142 Factory Radio: 4-Channel Amplifier Connection with RCA Output & LA4708N Power Tips

Question

I warmly welcome,

I would like to take the RCA output from the factory radio to a 4-channel amplifier.

Power tips (2 pcs) LA4708N Specification
The main unit: LC75385Y (replacement according to SANYO is LC75411ES ) Specification

A few pictures:

I would ask for more experienced advice:

I have a dilemma with the place where 4 RCA sockets are connected.

All help is welcome

Greetings,
Michael

cichy lis · Answer

for a peasant understanding then you have to find the signal input to the end of the power and plug in there (in front of capacitors)
The second option is a much easier adapter that can be made or purchased on the Allegro

mico84 · Answer

I connected to Input IN1 (leg 2) and IN2 (leg 7) of system , I used the electrolytic capacitor in front of each signal with 2,2uF 63V electrolytic capacitor, the mass was taken with PRE GND (foot 4). Unfortunately, deaf ... Question where the problem lies?

cichy lis · Answer

And after connecting eg the headphones do not hear anything? do you have these capacitors yourself or do you talk about the original ones?

mico84 · Answer

I can not hear anything, I checked on the receiver, on the loudspeaker and on the speaker with the amplifier. The capacitors were delivered by myself, I followed the diagram and in accordance with it I chose the value of 2.2 uF.

Perhaps you should connect to these places on the board (I greened):

cichy lis · Answer

This is marked on the left - is not GND? I can barely see but these points are as if they are connected - unless the record is two-layered.

Buddy, and it's not better to construct an adapter or buy it? combining should work - I do not understand why the signal reaches the tip do not work - As you have the power to work it can take out the capacitor (so that the signal does not reach the tip) and hook up with a handset without a capacitor - the signal should be!

Added after 1 [minutes]:

I watched the photo on the magnification and You're right - those marked points are the signal handle - a nice description of this cube is on the disc. Get stuck - it must work

mico84 · Answer

From what I've read, all adapters affect the sound quality. Moving outside is a temporary solution, as soon a new headunit will be purchased. I will try to stick to the place marked above. greetings

mico84 · Answer

Welcome,

Unfortunately, I tried, I stopped and I continued to silence.

I noticed that when I touch the rca plugs, the radio will turn off the right or left channels, or both, so it makes a short circuit, so it's definitely not the place to hook up.

Any ideas ?

Greetings,
Michael

mico84 · Answer

In the end, I succeeded, I joined the signal directly in the legs of circuit LC75385Y on the board:

front, right loudspeaker signal - pin 13
front, left loudspeaker signal - pin 22

I pulled the mass for RCA from the housing.

Such a procedure gives us 2 rca to go out to the amplifier.

I did not use additional capacitors.

greetings,
Michael

Karolo MPower · Answer

Buddy, can you post some photos? And what about the second pair of RCA?

mico84 · Answer

I do not need other photos than I have above, but if I wanted to, should not connect with signal directly into the legs of the LC75385Y system on the board:

rear, right speaker signal - pin 14
rear left signal speaker - pin 21

RCA mass - radio housing.

greetings

Added after 1 [hour] 12 [minutes]:

Well, I have a riddle radio in the car does not work .

At home, I checked the radio through an external receiver, and under loudspeakers with a built-in amplifier, on these two devices the radio works properly .

In the car - no

Is it necessary to connect capacitors to the signal?

I checked the voltage at the 4.42 V RCA output

Greetings,
Michael

Added after 23 [minutes]:

One more interesting ...

As I used capacitors (1 unit of 10uF for each signal) recommended by the datasheet above, one channel (right) was clearly louder than the left one.

However, I observed some phenomenon: right channel amplifier connected under RCA right front , while left channel amplifier under RCA left rear which resulted in no difference in the volume of channels.

one more question: what does the PA symbol mean in the triangle in the picture below:

greetings

cichy lis · Answer

Pa is a Power Amplifire (ie an amplifier)

mico84 · Answer

Thank you I do not want to believe that the lack of sound in both channels is due to the lack of capacitors.

mico84 · Answer

Below I present to you the solution checked by me , working both in car , under the external amplifier, and in home conditions . Required, after outputting a signal from each channel from the LC75385Y system, using the appropriate capacitor. Correspondingly for the front speakers (2 RCA), in the LC75385Y system find pin 13 , which is responsible for the signal in the right front speaker . It is soldered to a positive electrolytic capacitor foot with a value of 0.22 uF 50V . The negative foot of the capacitor to the RCA signal. The same operation is carried out for pin 22 responsible for the signal in left front speaker . Mass for both pull from the radio casing. When it comes to outputting the signal for the rear speakers, the principle of operation is almost the same, with the change that we use capacitors with the value 1uF 50V , and solder them accordingly: rear, right speaker signal - pin 14 rear left speaker signal - pin 21 greetings, Michael

Mitsubishi W142 Factory Radio: 4-Channel Amplifier Connection with RCA Output & LA4708N Power Tips

Post #1

Post #2

Post #3

Post #4

Post #5

Post #6

Post #7

Post #8

Post #9

Post #10

Post #11

Post #12

Post #13

Post #14

Topic summary