Author Topic: Becker mexico - amplifier upgrade  (Read 9750 times)

s class

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Becker mexico - amplifier upgrade
« on: 16 September 2009, 01:28 AM »
Hi,

I have a becker mexico pinstripe that I bought off Cam, and I'd like to get it going.  It is lacking the external amplifier, which is no big deal really as I'd like to use something modern.  So I need to know the pinout of the DIN cable that comes out of the radio - can anyone help?  Well, if goes further than that really, the cable has been cut already, so I actually need to know which colour wire is which in the multicore cable. 

I could of course just fire it up and play around.  I'm guessing there will be one or more grounds, and a left channel + and -, plus a right channel + and - .

'77 6.9 Euro, '78 6.9 AMG, '80 280SE, '74 350SE, '76 350SE, '80 280SE -parts, '81 500SEL euro full hydraulics

TJ 450

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Re: Becker mexico - amplifier upgrade
« Reply #1 on: 16 September 2009, 03:11 AM »
That was unfortunate timing... I just had mine out for an input modification. I am dissatisfied with the sound, as the shielding on the cable is insufficient... I can hear all sorts of interference. Needless to say, I will be removing it again and experimenting with different cabling.

Has the cable on yours been cut at the unit? What's what should be apparent when you separate the conductors. I think the signal cabling consists of a pair of shielded conductors within another layer of shielding.

My previous complaint with these units was a harsh, gritty treble and glassy midrange... I'm confident that all these issues lie in the cabling, as despite the background noise, the sound out of my unit now is remarkably free of distortion and goes quite loud with the W123 speakers. Thus, it would be worthwhile removing the original cable altogether and sourcing something better, or better still, mount some RCA jacks on the back of the Becker so you can use some modern cabling to your new amplifier and simply plug it in.

Tim
1976 450SEL 6.9
1988 560SEL ECE
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“If this is the best of all possible worlds, what then are the others?”
― Voltaire, Candide

s class

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Re: Becker mexico - amplifier upgrade
« Reply #2 on: 16 September 2009, 03:41 AM »
...... or better still, mount some RCA jacks on the back of the Becker so you can use some modern cabling to your new amplifier and simply plug it in.

That is rather clever, embarrased I didn't think of it. 

'77 6.9 Euro, '78 6.9 AMG, '80 280SE, '74 350SE, '76 350SE, '80 280SE -parts, '81 500SEL euro full hydraulics

s class

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Re: Becker mexico - amplifier upgrade
« Reply #3 on: 16 September 2009, 03:43 AM »
Well, step 1 will be to get it working.  Step 2 will be the amp connection (probably RCA as you suggest).  Step 3 will be the koan-style input modification, though I will be mounting the connection at the back.  My intended use for the extra input will be an external CD changer.  I don't know too much about whats on the market - can one buy units that have a stereo line out? - and presumably some form of remote control?

'77 6.9 Euro, '78 6.9 AMG, '80 280SE, '74 350SE, '76 350SE, '80 280SE -parts, '81 500SEL euro full hydraulics

s class

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Re: Becker mexico - amplifier upgrade
« Reply #4 on: 16 September 2009, 03:44 AM »
My previous complaint with these units was a harsh, gritty treble and glassy midrange... I'm confident that all these issues lie in the cabling,

Is this with the original becker amp, or some other unit?

'77 6.9 Euro, '78 6.9 AMG, '80 280SE, '74 350SE, '76 350SE, '80 280SE -parts, '81 500SEL euro full hydraulics

TJ 450

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Re: Becker mexico - amplifier upgrade
« Reply #5 on: 16 September 2009, 03:50 AM »
That's with the original amp, as there is no form of noise filtering. I fitted an RF choke like I seem to recall seeing on Koan's amp.

I mounted a full size stereo TRS jack on a dongle out the back as per Koan's instructions too.

Tim
« Last Edit: 16 September 2009, 03:52 AM by TJ 450 »
1976 450SEL 6.9
1988 560SEL ECE
----------------------
“If this is the best of all possible worlds, what then are the others?”
― Voltaire, Candide

Papalangi

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Re: Becker mexico - amplifier upgrade
« Reply #6 on: 16 September 2009, 08:27 AM »
A quick search came up with this which unfortunately is not quite what you wanted,
http://www.crutchfield.com/p_130FM1289/Pioneer-Premier-CDX-FM1289.html?tp=133

I've searched using "universal cd changer" and "add on cd changer" and so far only come up with FM modulated units.

This one is cheap at $109 from http://www.onlinecarstereo.com/CarAudio/ProductDetail.aspx?ProductID=18393
Michael
1976 450SEL, 116.033  Sold it to buy a '97 Crown Vic.  Made sense at the time.
1971 250C, 114.023      Sad but true, it's gone to a new home.
1976 280C  Stolen by the City of Seattle, sort of.
1970 250/8, traded in on a 1993 Land Rover Disco

s class

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Re: Becker mexico - amplifier upgrade
« Reply #7 on: 22 September 2009, 05:07 AM »
OK, I have been playing with the Mexico.  I had about 50mm remaining of the umbilical cord, and I stripped it back, and then stripped the constituent wires.  I found about 4 coaxes, and several other thin wires.

I powered the unit up and probed the outputs with an oscilloscope, and subsequently discovered that at least half the wires in the bundle don't go anywhere, and pulled out easly.  I was left with the screen (ground), a thick +12v supply and two coaxes - left and right audio presumably.  So in the end it was quite simple. 

What I see on the audio lines with the oscilloscope is not what I expect, but admittedly I didn't have an aerial connected.  So the next step is to give it an antenna, and perhaps put the audio into an amp and speakers so I can hear what's going on. 

I fitted a new belt to the cassette mechanism, but it is still not engaging.  More investigations needed. 

'77 6.9 Euro, '78 6.9 AMG, '80 280SE, '74 350SE, '76 350SE, '80 280SE -parts, '81 500SEL euro full hydraulics

Papalangi

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Re: Becker mexico - amplifier upgrade
« Reply #8 on: 22 September 2009, 09:17 AM »
I don't know how much if any info this guy will share but he does sell a cable that plugs into the DIN socket on the back of the radio to add an input.  They used to be for the Mexico's with cassette but now he lists them as only for radios without cassette.

http://www.koenigs-klassik-radios.de/_py_accessories/c-28-0-0-0-0-0/

Michael

1976 450SEL, 116.033  Sold it to buy a '97 Crown Vic.  Made sense at the time.
1971 250C, 114.023      Sad but true, it's gone to a new home.
1976 280C  Stolen by the City of Seattle, sort of.
1970 250/8, traded in on a 1993 Land Rover Disco

TJ 450

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Re: Becker mexico - amplifier upgrade
« Reply #9 on: 22 September 2009, 10:35 AM »
I was led to believe that those DIN inputs were mono, but there may be exceptions.

I don't know what you had the scope on s class, but it may have been out of band noise or similar in the audio signal. The extra conductors may have been for shielding purposes.

Tim
« Last Edit: 22 September 2009, 10:39 AM by TJ 450 »
1976 450SEL 6.9
1988 560SEL ECE
----------------------
“If this is the best of all possible worlds, what then are the others?”
― Voltaire, Candide

s class

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Re: Becker mexico - amplifier upgrade
« Reply #10 on: 22 September 2009, 11:25 AM »
I think the DIN input is indeed mono - intended for use with the VK5 kurier. 

TJ, I expected to see the audio signal (which is presumably mostly noise at this stage) increase and decrease with the volume control, but that was not the case. 

'77 6.9 Euro, '78 6.9 AMG, '80 280SE, '74 350SE, '76 350SE, '80 280SE -parts, '81 500SEL euro full hydraulics

koan

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Re: Becker mexico - amplifier upgrade
« Reply #11 on: 22 September 2009, 03:04 PM »

I found about 4 coaxes, and several other thin wires.


Doesn't sound right, shouldn't be that many connections, some one may have got at it.

That DIN socket on the back for the "Radio Traffic Adaptor" needs a shorting plug with pins 1 and 2 jumpered for the radio to work normally.

I've read somewhere the sockets are mono early and stereo post Mexico.

I have a circuit scanned in if it's any use.

koan
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Papalangi

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Re: Becker mexico - amplifier upgrade
« Reply #12 on: 22 September 2009, 04:43 PM »
I think there are two socket on the back of the Mexico but could be quite wrong.  The Europa II sitting in front of me has an input for a traffic adapter and an stereo input for a record player or tape recorder.

This place claims to have service manuals in PDF but I've no idea if they are telling the truth. http://www.becker.manuals-in-pdf.com/becker-c-242.html?page=1&sort=20a

If you can get FM modulators there you could record a test tone and play it back through a modulator to identify left VS right.

Michael
1976 450SEL, 116.033  Sold it to buy a '97 Crown Vic.  Made sense at the time.
1971 250C, 114.023      Sad but true, it's gone to a new home.
1976 280C  Stolen by the City of Seattle, sort of.
1970 250/8, traded in on a 1993 Land Rover Disco

s class

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Re: Becker mexico - amplifier upgrade
« Reply #13 on: 23 September 2009, 02:28 AM »
My mexico has the DIN socket on the back, with the shorting plug still present.  I also have an additional "mini" DIN socket, the purpose of which I dont know. 

'77 6.9 Euro, '78 6.9 AMG, '80 280SE, '74 350SE, '76 350SE, '80 280SE -parts, '81 500SEL euro full hydraulics

Big_Richard

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Re: Becker mexico - amplifier upgrade
« Reply #14 on: 23 September 2009, 02:56 AM »
indeed, there is a mini din connector of 8 pins, i just looked at my old one. What does this connect to ?