Problem when daisy chaining the ground wire

[frynturn]

I have an interesting problem that is simply doing my head in because it should be sooooo simple.

I have a premade daisy chain for grounding my buttons which works fine, unless, you skip a connector in the chain.  If you do that then all of the buttons after that skip don't work.

In the picture below my wire goes from the ground on the ipac, 1st connector is empty, 2nd connector goes to P1 start, 3rd/4th connectors are empty, 5th/6th connectors go to P1 buttons 1&2.   Only the P1 Start button works?!



So I'm thinking there is a break in the chain somewhere but the weird thing is that if I disconnect the 2nd connector from P1 start button then suddenly the P1 buttons 1&2 start working!  Similarly if I leave connector 2 fixed to P1 start and chuck a couple of spare microswitches on connectors 3&4 I get all 3 buttons working.

So it can't be a break in the chain and it has left me stumped. 

Please embarrass me and tell me the obvious thing I am doing wrong.

[Malenko]

has to be an issue with your crimping / break in the chain. Perhaps the switch being inserted is enough to fix the break?

[Louis Tully]

.

[frynturn]

I'll get the multimeter out again tomorrow and have another crack to see if I can find any bad crimps.  Continuity testing I did yesterday was fine but maybe I'll check resistence and see if there is any differences along the wire.

I just wanted to check there was no twilight zone thing happening I wasn't aware of.  There should be no reason why I can't skip connectors because everything is all joined together.

[PL1]

In addition to the continuity/resistance checks when powered off, do voltage checks when it's powered on.

You may have a microswitch (or two) that is intermittently open/shorted depending on the force applied to the COM tab by the ground chain.

Sometimes gently wiggling the wire/tab will reveal the intermittent while testing with your multimeter.


Scott

[matsadona]

Are you 100% sure that you haven't connected the ground wire to any of the NO/NC pins by mistake (instead of the common pin)?

[Generic Eric]

I've connected the wires to the wrong connector before.  I've also made crimps that didn't hold.  I've even changed out a switch.  Of things that are cheap in this, wire and crimps are among them.  I wouldn't spend to much time on it, if it isn't obvious now.  Sounds like getting close to time to recrimp.
 

Happy sleuthing.

[dkersten]

One daisy chain ground I got was full of bad crimps, and would have shown the same kind of intermittent issues that the OP is having.  Meter from one end of the chain to the other to check resistance, if it is more than a few ohms (or no connection), you have bad crimps, whether it is hooked up wrong or not.  I was seeing something like 47 ohms even after fixing two completely breaks in the chain and found almost every crimp to be loose.  Once repairing I dropped the resistance from end to end down to about 2 ohms. 

[matsadona]

Except from that I'm lazy, this is the reason why I stopped crimping in my projects. Soldering is the way to go for me nowadays

[Sarver Systems]

I prefer to solder the factory-made crimps.

[SavannahLion]

I prefer to solder the factory-made crimps.

Same here. When I can.

When I was younger and knew little about electricity, I had a harness that had an intermittent connection somewhere. I couldn't pull the entire harness so I applied solder (badly) to the crimps. Problem went away.

Crimping is great if you do it right and have the right tools but I always have at least one bad crimp somewhere that bites me in the ass later.

[Vigo]

90% of the crimpers on the market suck. One hand tool probably worth spending a little extra money on.

[Sarver Systems]

90% of the crimpers on the market suck. One hand tool probably worth spending a little extra money on.

I couldn't agree more.

[SavannahLion]

To be honest, I would like to know what tool that is. Local hardware stores sell crap.

[yotsuya]

Screw this kind, where the crimpers are in the front...



Someone here recommended this style, where the crimps are on the back side, and it has been soooooo much better on my hands....

[Generic Eric]

To be honest, I would like to know what tool that is. Local hardware stores sell crap.

I bought this one (for less than it is listed)



It works better than the generic one at the hardware store.

[yotsuya]

Or, what Eric said.

[Generic Eric]

Or, what Eric said.

:ha:
No, like you said.  You said it first. 

[PL1]

Ratchet crimpers FTW.

http://forum.arcadecontrols.com/index.php/topic,135379.msg1398034.html#msg1398034


Scott

[wp34]

Using the wires from a cheap Jamma harness might be one of the best pieces of advice I've seen on this forum.  I just did this on my Tron CP and wow what a time-saver.

https://forum.arcadecontrols.com/index.php/topic,132248.msg1358554.html#msg1358554

[yotsuya]

Ratchet crimpers FTW.

I use ratchets for Molex (thanks, Neph!), but not QDs. However, if conked out on me, I'd look at a ratcheting one for QDs.

And yeah, wires from a cheap JAMMA harness is my favorite method, too.

[Vigo]

Paying a little extra for a good stripper is worth it, too. The cheap ones you end up sitting there having to yank on your wire forever trying to get it off. You get some classy strippers that do a more thorough job and they will pull your wire clean off for you. Well worth the money.

[Generic Eric]

Paying a little extra for a good stripper is worth it, too. The cheap ones you end up sitting there having to yank on your wire forever trying to get it off. You get some classy strippers that do a more thorough job and they will pull your wire clean off for you. Well worth the money.

I feel like having a cigarette after that.

[dkersten]

This is what I have been using now for about 24 years.  I use this for crimping anything from red to yellow insulated crimps (22-10 ga), and it can go a little smaller too although you don't see insulated crimps below 22 ga that often.  This would be for the QD, butt connectors, crimp caps, bullet type QD's, spades, forks, etc.  I bet my pair of T&B crimpers has seen well over 200,000 crimps, but then I used to do that 100s of times a day.
http://www.amazon.com/Thomas-Betts-WT111M-Insulated-Terminals/dp/B0018LD2PU/ref=sr_1_5?s=power-hand-tools&ie=UTF8&qid=1409260759&sr=1-5

For "OEM" style crimps (the kind that crimp both the wire and the insulation and then you slide the insulator over it all), I use this type:
http://www.amazon.com/Barrel-Terminal-Crimping-O-E-M-Terminals/dp/B0040CZ1F8

I use ratcheting for coax and compression crimping, and I have a ratcheting now for the 2.54mm DuPont style pins, but I don't like the one I got, the teeth for it are not defined enough and it just doesn't work well.

For stripping, the type shown above works well, and if you want something a little easier to use, something like this works surprisingly well, although they don't hold up well over time:
http://www.amazon.com/Neiko-RI-01908-Automatic-Wire-Stripper/dp/B000KT791Y/ref=sr_1_40?s=hi&ie=UTF8&qid=1409260837&sr=1-40&keywords=wire+stripper

Honestly, I have just used the cutter at the end of my T&B crimper to strip wires pretty much all the time.. Even 15 years after I stopped doing it daily, I still have the callouses on my fingers from it.. lol.

As for soldering, not everyone knows how to do it properly and you can get a worse connection than a crimp pretty easily.  Solder is not a great conductor by itself, so having good contact between the wire and the terminal before you apply solder is key.  Also, making sure you don't move the wire before the solder solidifies is very important because you can make a bad connection even worse and also end up with a cold solder joint that can break off very easily.

[frynturn]

Thank you all for the replies. 

The problem turned out to be a loose wire at terminal #4.  It was just barely loose and giving it a good wiggle still didn't really show it as being loose (however the multimeter was saying otherwise).  I guess the physical act of pushing the connector on to something must have been enough to push the wire against the connector to make a circuit.  Also might explain why when I first tested with the multimeter it was fine as the probes probably did enough to press the wire against the terminal.

I will definitely be looking into a ratcheting crimper to do the wiring in my final build but the store bought wiring has done enough to let me test everything first

Happy Building.

[Malenko]

yay I was right.