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DIY harness for car amplifier?

primuspaul

Feb 7, 2018
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Is it possible to build a custom harness (assuming the original harness is missing) that is compatible with the pins (shaped like blades) of this head unit?

stereo.png

Also, if I want to solder/crimp on connectors to those copper wire ends, what is the best type of connector to use? Dupont? Bullet? What AWG?
 
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KJ6EAD

Aug 13, 2011
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Automotive applications including to a lesser extent third party audio are notoriously proprietary about their connectors. Consequently, it's very difficult to source matching pieces. As you found, there are some aftermarket suppliers like Crutchfield that specialize in solving some of the more frequently wanted bits but complete, correct harnesses are the exception. Kludgy, multiply-jointed tape and solder or abbysmal plier crimp jobs are the rule.
 

primuspaul

Feb 7, 2018
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Automotive applications including to a lesser extent third party audio are notoriously proprietary about their connectors. Consequently, it's very difficult to source matching pieces. As you found, there are some aftermarket suppliers like Crutchfield that specialize in solving some of the more frequently wanted bits but complete, correct harnesses are the exception. Kludgy, multiply-jointed tape and solder or abbysmal plier crimp jobs are the rule.
What about soldering a connector to the other side?
 

KJ6EAD

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What about it? You have wires which you're free to terminate in whatever manner you please. My preference is a crimped pin connector but those short leads that come with your universal connectors are targeted to the solder blob and tape crowd. Many automotive shops sell generic multi-pin connectors that are pre-pinned with leads. The only crimp connectors readily available to DIY, non industrial savvy users are the spade and bullet types.
 

primuspaul

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What about it? You have wires which you're free to terminate in whatever manner you please. My preference is a crimped pin connector but those short leads that come with your universal connectors are targeted to the solder blob and tape crowd. Many automotive shops sell generic multi-pin connectors that are pre-pinned with leads. The only crimp connectors readily available to DIY, non industrial savvy users are the spade and bullet types.
Yes, that's what I mean. Let's say I have the harness that plugs into the radio and has bare copper wire at the other end. Then I buy a Toyota-compatible harness that plugs into the harness that comes out of the car wiring behind the original stereo. That has bare wires on the other end.

Obviously the most obvious solution is to solder and/or crimp the two sets of bare wires together and shrink seal them from coming into contact with each other. But what if you think you'll be putting in a different radio into that car at some point in the future? To avoid buying a new car end harness (we're assuming the stereo comes with the stereo end harness), you can solder/crimp bullet/spade connectors to each of the above mentioned sets of bare wire ends and plug them in as you want.

I've seen the spade and bullet connectors. The main problem I see is bulkiness, as you typically need to crimp up to 11 wires (2 +V12, 1 GND, 8 audio). That's why I started looking at things like the 2.54mm Dupont connectors and was wondering if they are big enough to accommodate whatever AWG wire comes with these harnesses since I see this as superior to the bullet/spade variety of connectors.
 

KJ6EAD

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Of course, it's just that most people don't have or want to acquire the more specialized crimping tool needed for the better connector option nor does the typical automotive DIYer have the requisite skills hence my comment about solder blobs and tape.
 

primuspaul

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Of course, it's just that most people don't have or want to acquire the more specialized crimping tool needed for the better connector option nor does the typical automotive DIYer have the requisite skills hence my comment about solder blobs and tape.
Right, but if I were getting the tools, which particular connection would you recommend for those particular wires?
 

KJ6EAD

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For the number of wires you describe, I'd probably get a 12-position Molex 0.093 connector. There is a Molex generic open barrel hand crimp tool that sells for ≈$40. You need to pay attention to wire gauge when buying the pins.
 

primuspaul

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For the number of wires you describe, I'd probably get a 12-position Molex 0.093 connector. There is a Molex generic open barrel hand crimp tool that sells for ≈$40. You need to pay attention to wire gauge when buying the pins.
Anyone sell that stuff in bulk? Looks like those are literally 10x the price of Duponts (the connectors, not the crimp tool) on eBay.
 

KJ6EAD

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You can get them from most electronic suppliers; Digikey, Mouser, Jameco, some automltive shops and any local electronics shop if you have one.

I have no idea what you're referring to by "Duponts". I'm aware of the company but they make thousands of things across multiple industries.
 

primuspaul

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You can get them from most electronic suppliers; Digikey, Mouser, Jameco, some automltive shops and any local electronics shop if you have one.

I have no idea what you're referring to by "Duponts". I'm aware of the company but they make thousands of things across multiple industries.
https://www.ebay.com/itm/100Pcs-Fem...ch-Dupont-Jumper-Wire-Cable-HICA/152941642075

They come in male and female variety and get inserted into a hard plastic sleeve once soldered/crimped
 

primuspaul

Feb 7, 2018
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That's the right type (F crimp). The packaging lists a range from 28 – 18 AWG so unless some of your wires are bigger than 18 AWG, you should be good.

Take a look at this thread for some advice on F crimps:
https://www.electronicspoint.com/threads/crimp-bullet-shur-connector-te-connectivity.288585/
I used a gauge circle to measure the wires. It is a used unit so the harness had solder on it, but as is the wires came up 21 AWG for most and 16 AWG for the power, so I'm thinking it might be 18 AWG without the solder.

Anyone know why they use a dedicated line for each audio GND connector instead of using the common chassis ground like they do for power? So if I for example put in my own speakers into the car and wired the head unit's GND and the speakers' GND to the chassis, would it work fine?
 
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primuspaul

Feb 7, 2018
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Anyone know why they use a dedicated line for each audio GND connector instead of using the common chassis ground like they do for power? So if I for example put in my own speakers into the car and wired the head unit's GND and the speakers' GND to the chassis, would it work fine?
Just wondering if anyone has an answer for the above. I was searching on google and couldn't find a solid answer. Is it to prevent ground loop hum in the audio or something?
 
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