Audio wiring diagram for E300TD 1992

mick1jones

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I am attempting to work out the rats nest of wires so I can fit a new audio system. Can anyone let me know how I can get hold of audio wiring diagram with associated colour codes?
 

Bolide

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Just work it out with a voltmeter and a 9 volt battery to check which speaker is which. Most ISO connectors you buy have the wires marked so locate the corresponding wire for each one & crimp it on using a butt connector & a crimp tool

Nick Froome
 

MotardMan

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Don't do that. It makes it horrible for the next guy... WhatsApp Image 2019-06-17 at 09.14.25.jpeg WhatsApp Image 2019-06-17 at 09.14.31.jpeg
 

Tony Dyson

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Not only horrible for the next fellow but these connectors are unsuitable for AV connections due to the high resistance of the joints x 3 for every connection you make of this type. There are a plethora of appropriate AV connectors available all of which are gold plated and some requiring special tooling and if you're adding to your AV installation to improve the quality of sound, I would recommend you decide one of those available, if you're just looking to add more noise then either of these cost effective alternatives would work far better than the crimp connectors in the picture;

https://www.ebay.co.uk/itm/180X-Kit...m=312594886605&_trksid=p2047675.c100005.m1851

Or even better these;

https://www.ebay.co.uk/itm/65Pcs-As...101587&hash=item41fa705e4e:g:glkAAOSwb7RcYT3Z
 

LostKiwi

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God no! Not those!!!
To do it properly solder and heatshrink is best.
 

Tony Dyson

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Technically, Copper-Copper connections as the first suggestion will be the connections of least resistance.
Copper-Gold-Gold-Copper as in proprietary connectors will be next best due to the low electrical impedance of Gold.
Copper-Tinned Copper-Copper would be next in line as my second choice as the cutting edge of the guillotine meets directly with the copper conductors.

Soldering is largely dependent upon several factors, the type of solder/flux used and the method of pairing the joint bearing in mind, whichever is chosen, solder will flow between all the copper wire surfaaces and form a Copper-Solder-Copper Joint and could potentially form the connection of highest electrical resistance.

As I said in my earlier post, and bearing in mind you are only transporting mA in the speaker feeds, if you're just looking to add more noise to your sound system then it's almost irrelevant which method you use. I personally wouldn't use Heatshrink on soldered spliced connections, Silocone Cable Sleeves are the way to go there.

https://uk.rs-online.com/web/p/cable-sleeves/3031877/
 

LostKiwi

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solder will flow between all the copper wire surfaaces and form a Copper-Solder-Copper Joint and could potentially form the connection of highest electrical resistance.
I disagree. Resistance of a joint us about contact area as much as materials. As solder gives a very high contact area relative to other methods and inherently seals the connection from outside air when done properly it gives good low resistance connections. In my view if solder is good enough for the internal connection of components to circuit boards it's good enough for joining wires together.
The only time I would not use solder is for very high current applications such as battery cables where the cables can heat up under load and potentially compromise the joint. In this case proper hydraulic crimped connections (using several tons pressure) are superior.
 

Blobcat

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What our flightless antipodean friend said :D

I still gain great pleasure from a perfectly made electrical joint whether it be crimp solder, screw terminal or splice. I used to make lots of RF connections in a previous life and you either get the hang of it or you don’t. RF joints and connections need to be perfect otherwise you can blow the output stages of your transmitter or have very poor reception from your receiver. None of this is particularly relevant for standard car audio although still good practice, you want all the signal or power going to where you want it not getting reflected or lost with high resistance.
 

Tony Dyson

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Well you’re both right within the context of your own relative applications, but let’s not lose sight of what the subject of discussion is here, it’s not the delivery of power to a big electrical consumer, neither is it an RF Signal, it’s an Ultra Low Voltage, Low Current, Analogue, Alternating Current Signal whose waveform is interpreted and modulated from the Audio signal received by the speaker it is connected to, which then translates the Analogue Signal received back into sound.

The design voltage in any given circuit plays an important part of the delivery of what it is designed to ‘push through the pipe’ this is why voltage is often referred to as ‘Pressure or Tension’, I think we are all aware of the problems a failing battery can cause in a car, a corresponding reduction in the waveform modulation of the audio signal will result in the deterioration of the frequency responses at the speaker starting from the high end to the low.

Changing either the speaker’s internal impedance (Resistance) Supply Voltage or circuit resistance will affect the signal quality and as we’re only dealing with mV’s as a supply voltage, the speaker circuit resistance will play a far greater part in the efficient delivery of a quality signal to the speaker.

The average resistivity value of a generic 5c solder is around 10x that of Copper Wire when you have 12/24/240v AC or DC Pressure pushing through the circuit this difference in overall circuit impedance is irrelevant but it is a very different story when you only have mA to start off with, simply by soldering the mechanical joint and introducing an additional barrier of an inferior conducting material you will increase the circuit impedance risking further deterioration of the higher frequencies in the signal.

As I stated previously, my comments re adding quality or noise are relevant, I think if a member is going to the added and probably considerable expense and lengths of upgrading a car’s sound system, it would matter to an Audiophile, if you’re more interested in a Sub-Woofer in the boot, it’s probably not that important!
 

LostKiwi

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Solder seems perfectly adequate for other very low current low voltage applications. The computer or phone you're using now is a classic example.
All the internal circuit connections are soldered, that's hundreds of individual solder connections operating at frequencies between DC to several GHz.
Same with the quartz watch quite possibly on your wrist - that's extremely low current and voltage.
The internal connections of the speaker from the terminal tag to voice coils are generally soldered.
The voltage and current is also not exactly low - a typical head unit will put out 25W per channel after all.
 

Tony Dyson

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And I’m sure the manufacturers have carried out all their design functions correctly in all their different applications, I’ve tried to explain in leyman’s terms it’s about the quality of signal in this particular situation getting through to the speaker, not the quantity, and while a Max Amplifier power output is rated at X, it’s the RMS values and less with most quality manufacturers using figures as low as 40% of the Max values in their calculations, the same applies to speaker outputs all for quality reasons and spread across the 6-13 speakers found in a modern car reduces the figures you quoted in the speaker circuits significantly.

Again, I’m not advocating everyone should not consider using soldered joints in their cars anymore and I find my Audio 20 with 6 speakers more than adequate for my purposes but some members would want to improve on that and the more discerning would feel the need to achieve the best results possible, any additional connections in a circuit of any specification will introduce additional impedance and the best option is of course to replace the cable in it’s entirety without additional joints, but as in this case the better quality of joint would be the best option for a quick fix. Anything you introduce between the two copper wires will have a negative effect on the signal it is designed to carry.
 

MotardMan

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I give you, my use Case....... IMG_20190617_091340.jpg
And the challenge is.....

Loom Hack.jpg

:)
 

Tony Dyson

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Well I'm sure you have enough information already provided in order to make your own informed decision, Good Luck with your project!
 

mattkh

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Very informative.
Would the 'WAGO' style connectors have less resistance?
What about the resistance when using car audio industry supplied connectors?
 

MotardMan

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Very informative.
Would the 'WAGO' style connectors have less resistance?
What about the resistance when using car audio industry supplied connectors?
I think that the point here is I am making a running repair in preparation for the big refurb further on down the road. Excuse the pun. The components and cabling are old. Very old. The connections are poor, very poor. So whatever I do, for the next twelve months, it'll work. I'll have the wireless. I'll have CD.

I PROMISE when the time comes, I'll revisit this thread and thank you all for the great advice and perspective.
 


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