How do you deal with d-subs and tiny wires?

[Jamie]

Guys:

I'm tidying up my electrical stuff on my -7A. I have both aileron and elevator electric trim on both sticks and am consequently using relays. I'm using the RAC grips 207 and 205 grips.

Anyway...I'm curious how people deal with d-subs and those tiny trim wires. Here are my options:

1) Throw out the d-sub connectors and just connect the pins together and heatshrink over them. I've done this in some other places but I wanted to make it easier to remove the relays when (not if) they fail.

2) 'Lectric Bob's shoe goo connector deal, which I presume he does for vibration insulation purposes.

3) Use solder d-subs instead of the crimp style, then heatshink each wire over the solder connection for vibration insulation.

I guess my main concern is that those wires are VERY fragile. I've already crimped a couple of pins that easily fell off when I did a pull test. I don't want to be chasing trim wires in the future. Also, I feel that there exists a safety of flight issue here. If the elevator trim runs away it's going to make for an interesting landing. :-)

Thanks,
Jamie (sort of wishing I would have just done manual trim)

[Low Pass]

Originally Posted by Jamie

Guys:

I'm tidying up my electrical stuff on my -7A. I have both aileron and elevator electric trim on both sticks and am consequently using relays. I'm using the RAC grips 207 and 205 grips.

Anyway...I'm curious how people deal with d-subs and those tiny trim wires. Here are my options:

1) Throw out the d-sub connectors and just connect the pins together and heatshrink over them. I've done this in some other places but I wanted to make it easier to remove the relays when (not if) they fail.

2) 'Lectric Bob's shoe goo connector deal, which I presume he does for vibration insulation purposes.

3) Use solder d-subs instead of the crimp style, then heatshink each wire over the solder connection for vibration insulation.

I guess my main concern is that those wires are VERY fragile. I've already crimped a couple of pins that easily fell off when I did a pull test. I don't want to be chasing trim wires in the future. Also, I feel that there exists a safety of flight issue here. If the elevator trim runs away it's going to make for an interesting landing. :-)

Thanks,
Jamie (sort of wishing I would have just done manual trim)

Got a buddy that likes the crimp style. I soldered all mine. Just have to make sure you have a hot iron, clean connections and a good bond. (Knock on wood) have had only one bad connection in almost 900 hrs. Was in a transponder encoder connector back around 40-50 hrs. IMO, it's easier for me to tell that I have a good joint when soldering.

I just converted from hardwired Infinity stick grip to that having a d-sub connector. PITB soldering all those little wires - but not as much as much as having to deal with all those leads hard-wired into the plane.

I have 4 or 5 others soldered d-subs in various locations in the plane with no problems. Will have to check out the Shoe Goo thing. I guess this is where you'd glue the leads at the connector to prevent vibration damage?

[Bob Brown]

Hey Brian,
FWIW, I always doubled the tiny (24&26ga) wires back on themselves before crimping the pins. Be careful not to trim off too much insulation or you'll end up with a mechanically weak connection. I used itsy bitsy heat shrink (not too far forward on the pin or you'll be unable to seat the pins in the d-sub) on the back of the pins. I then used another (larger) piece of heat shrink around the wires as they go into the back of the d-sub.

Inside the stick and in other places where I wanted a splice, I simply used the male/female pins as connectors, and then used heat shrink over them. If you find the right fit on the heat shrink, these make a great connection. On some cables, you need to sequence your splices so you don't end up with a big bundle of splices in one spot.

I assume you are not planning on using d-subs INSIDE the stick tubes...that seems a little tight to me.

[Mike S]

how are you crimping the joints?? Regular automotive crimper's wont work well on such tiny pins.

Check out the crimper just for d-subs here http://www.steinair.com/tools.htm

Part sat 004.

While using solder is an alternative, the solder tends to wick up the wire, and stiffen it, ends up causing a place for the wire to weaken/break. Be sure to use shrink tubing or some other method as shoo goo to support the wires out to past the solder.

Mike

[kentb]

Stip back a little extra and then double back to make a better connect with the crimper.

Kent

[Jamie]

I forgot to mention that I'm using Stein's 4-day indent crimper.

On my pax stick I have a Molex inside of the stick to make it removeable but that's it. The rest of the stuff is just for make the relays and the servos easily serviceable.

Oh yeah...one neat thing that I did was pull a separate ground run to the pax stick to a switch on the instrument panel. Flipping the switch enables pax trim. That way I don't have to worry about white-knuckled pilots in the right seat hitting the hair trigger trim buttons on top of the grip.

[JimP]

I don't have the link handy, but Digikey has a micro-Molex connector that may work well. I bought a bunch of the 6-pin connectors/ pins but haven't given them a try yet.

Jim

[RudiGreyling]

Originally Posted by JimP

I don't have the link handy, but Digikey has a micro-Molex connector that may work well. I bought a bunch of the 6-pin connectors/ pins but haven't given them a try yet.

Jim

Jim, do you have an online source for those??

[az_gila]

Originally Posted by RudiGreyling

Jim, do you have an online source for those??

Rudi,

DigiKey has a good on-line web store.

I believe these are the connectors referred to above...

http://dkc3.digikey.com/PDF/T071/0157-0159.pdf

They don't mind small orders...Small fee added if order is under $25...

Handling Charge
A $5.00 handling charge applies to all orders less than $25.00. This fee will be waived on orders of $25.00 or more.
A $6.00 processing fee will be applied to all International orders, excluding Canada.

gil in Tucson

[JimP]

The part number I have is A25660-ND (Mini Univi Mate 2). Again, I haven't tried these yet but they are the right size and look like they will do the job. You'll need to order the associated pins with these as well.

As Gil mentioned, Digikey has a nice on-line catalog, but with so much stuff, it's sometimes hard to figure out what you want/ need. I find their service is some of the best. I normally get an order in 2-3 days max and order size isn't an issue. Again, weeding through the catalog or even the hard copy takes a little doing.

Jim