To JST, or not to JST... that is the question

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msknight

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May 15, 2018
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Sussex, UK
I finally took apart the Aiwa TPR 950 and have started working on it. However, it has loads of wires soldered to the baords, but with no connectors. Probably down to its age. Net result... a heck of a lot of soldering and de-soldering required, unless I get smart.
I've spied JST connectors...
Maximum Voltage: 30v DC
Maximum Current: 3 Amp
Supported Wire Size: 22 AWG - 28 AWG
Should I use them, to make life (and future maintenance) easy? Or not? And if not, why not please? I believe that 3 amp should be enough for the internal DC connections, but I don't know enough to be one hundred percent sure that I'm not going to end up causing a fire.
Especially of note, the black and brown cables curled at the bottom of the main board which are a little thicker than the others. However, AD/DC is by a transformer in the back of the unit, so there's no transforming going on in the main board, as far as I can see.
Advice from knowledgeable people would be gratefully appreciated.
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Superduper

Member (SA)
Would the connectors be a male plug for the wires and a female socket for the PCB? Because all I see are tons of individual wires soldered to individual solder pads. If not and you will be basically cutting individual wires to insert a quick disconnect in the middle, there will be a ton of them which adds bulk. And if there are going to be a ton of 1p and 2p connectors/sockets -- are you going to label them all? If not, then there is still going to be massive confusion. Then, there is the reliability factor -- you are introducing something that adds a layer of (potential) reliability concerns. I only speak from my own experience which is that connectors that float and not physically rooted at a PCB are less reliable -- wiggle them and they sometimes drop out. When all is said and done, unless you have cut and individually labeled all 50 (or however many plug/sockets you have added), it will still cause confusion when connecting them all. At the end of the day, it's a lot of work for no performance enhancement. True it may be somewhat easier to disconnect everything in the future, but how often do you plan on doing that? Except for a rebelting every 10 years maybe, if you think you will need more maintenance than that, perhaps the unit isn't reliable enough to be a keeper? I don't know.

In the end, it's up to you. Without knowing specific details of how you intend to accomplish this, I personally couldn't recommend this. However, if I were to decide to do this for my box, and I say IF, then I would use larger connectors that can disconnect many wires at a time. Build it up one wire at a time and place the connector at a suitable location. Then each subsequent wire will be added and shortened or extended as necessary to create a "bundle". For each bundle, use a different number of conductors (16, 10, 6) etc. Doing it in this way allows you to end up with just a few bundled connectors to connect/disconnect and no mistaking which connector connects with which receptacle. Ideally, you will populate the bare connectors by crimping your own terminals. Doing it this way means you won't have 100 spliced wires insulated by electrical tape and/or heat shrink tubing. Although notihg wrong with heat shrink tubing -- a ton of them adds up to make for a huge mass.
 

msknight

Member (SA)
May 15, 2018
9
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Sussex, UK
I'm planning to use JST connectors. They come in varied groups, 2, 3, 4 and 8 - https://www.ebay.co.uk/itm/5-Pairs-8-PIN-JST-SM-Plug-Socket-Connectors-Soldered-Crimp/273303123673

The cables are coloured clearly, so it should be possible for me to make groups which are easily identifiable. Also, if I cut the wires and install these now, then I won't even have to de-solder the first time around. The tuner section can be accomplished with a 2pin and an 8pin. The main board will probably need a couple of 8 pins, and a 4 pin to cover the majority of the connections...at least the ones I can see at the moment.

The bulk aspect is a good point. I hadn't thought of that.

I got this unit because of its reputation, so I'm hoping that it is a keeper. That's why I'm taking my time and asking for thoughts and advice, rather than getting stuck in. The other thing I'm concerned about is the power draw and whether 3amp connectors are enough for the job.
 

Superduper

Member (SA)
This is a 9V box. 3-amp connectors mean that the connector can handle 27 watts. At it's max. That might be enough but for the power connections, you are probably better off with 5-amp for the power connections. Frankly, in my personal opinion, it's really a waste of time and money to go through all that. This isn't a car that you are going to be doing frequent oil changes on. You only fix when there is a problem and in all honesty, your time is better spent on "fixing" whatever is wrong than spending it on doing all this. I mean, are you afraid of soldering or does the charlottes web bother you? You generally don't need to unsolder everything anyhow in order to do what you need to do -- you usually only need to desolder a few wires here and there to gain access to do the task at hand anyhow.
 

msknight

Member (SA)
May 15, 2018
9
0
0
Sussex, UK
The C45 will also get recapped once I've done the Aiwa. Playing state of the Aiwa isn't easy to ascertain as one channel is dead and the radio isn't locking on channels properly, so the whole radio side is going to be re-capped, as is the main board, and then I'll be able to work out where the tape deck is. So I'm looking at potentially having to take it apart a number of times before I've handled all the faults; and that's what the main problem is going to be. I believe I'm going to end up assembling and disassembling this a number of times in order to clear everything.

The transformer is actually in the back of the unit, so it's DC leads heading into the main board and I don't have to touch anything on the mains side, fortunately.

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