Tech discussion > Wiring
How to wire a 24 circuit DL plug (Jim L method)
jimlfixit:
I thought it may be an idea to show how I wire a DL plug connector in case it helps anyone who hasn't done one before. This example is a 24 pair Van Damme cable wired to a typical 24 circuit DL channel connector as used for mics and multitrack connections as well as most user option DL's. This is just my method but see my comments at the end (if you can stay awake long enough).
Tools required: From top left and clockwise:
1 Hellerman rubber sleeve expanders. I use rubber sleeves rather than heatshrink so that is why this is included. Lubricating oil is also required (not shown).
2 Lacing twine (as used by SSL on their internal patchbay looms) I use this to secure the sheathing and separate the 3 batches of 8 wires for the DL.
3 Cable strippers (Stripmaster in this case). Notice the long spacer used with tape to measure the length of strip.
4 Core wire strippers. I have several versions but these cheap ones can strip both hot and cold wires at the same time.
5 Jewellers screwdriver used to push home various loaded crimps if required.
6 DL crimpers. These are ITT versions with a metal block to a hold the crimp.
1 I don't know anyone who does this but I strip the multicore insulation back 200mm and put some cable sheathing on. This is for three reasons:
1 It gives the loom more flexibility especially if the loom exits the DL at an angle (as used on patch panels rather than just hanging down from an SSL connector panel).
2 It allows the individual circuits to be orientated to suit their load positions within the DL (see picture in point 11).
3 Most importantly, this extra length allows you to properly strip and deal with the individual cables without having up to 32 circuits fanning out over a short 90mm length. This picture shows a length of SSL multicore unlike the Van Damme used in the rest of this post.
2 Tape the ends so that you can add suitable heatshrink and 175mm of 20mm sheathing. This is shown in its final place but move it up and over the multicore insulation to keep it out of the way so you can work on the 24 wires with about 200mm of access length. The masking tape label is only temporary by the way!
3 Separate the loom into lots of 8 circuits. I normally tie each batch of 8 together so I know which circuits they are. This also helps while you load the connector and saves you having to deal with 24 wires at once. The green ties were only used as I couldn't find my lacing twine in time!
4 Stagger the batches of 8 circuits into the DL. I normally stagger each batch of 8 circuits by cutting them to different lengths. 1-8 is the longest and 25-32 is the shortest. These differ in lengths by about 8mm. I leave 1-8 as 200mm, cut 9-16 down by 8mm, the 17-24 circuits (which are the other side of the centre section spindle) by 16mm and 25-32 by another 8 mm. By the way, I'm not advertising Snap On cutters here, I have had these since 1981 and they are still just about up to cutting a few cables at once!
5 I stripped the balanced circuit wires with the red Stripmaster strippers using the spacer with tape marking to get the required length. Notice that I left the insulation on the cables. You can now see the DL plug with the staggered batches of 8 in line with it.
6 Sleeve the circuits with heatshrink or sleeves ... your choice and another subject (both rubber sleeving and heatshrink have their good and bad points). This picture is actually for a different cable (3 x 12 pairs into one DL ...a separate subject) but shows the sleeving involved.
7 Once the insulation and drain wires are sleeved, I tend to crimp the drain wires first although this is not essential. By doing them now it gives an idea of how far back to strip the core wires (hot and cold) so that they are in line with the screened wire and also stops them fraying out while you deal with the core wires. I don't crimp the rear part of the drain wire with the sleeve as it would be too big (unless you use very small heatshrink) and may present problems when inserting or removing in/out of the DL. When you crimp these drain wires, you will have to twist them tightly first and chop off any excess. Notice I have now secured each batch of 8 wires with lacing twine.
8 I used the small black strippers to strip the hot and cold wires in one go. Again, twist them after stripping and end up with about 3mm so that they fit into the crimp with the rear part of the crimp holding the wire insulation unlike the screen (see point above).
Inspect and tug all the wires. This is important and I have a careful look in case the conductive part of the wire is not making proper contact with the crimp. If not, it may be able to be removed or, failing that, you could possible carefully solder the crimp and test it out from the other end. If your eyesight is not too good, use a magnifying glass.
I tug the wires by grabbing hold of the crimp and tugging it a few times. With the proper crimp tool used there should not be a problem but if it is faulty or you have only partly crimped the wire, it may come loose. This picture shows the wires after tugging hence not being straight (Stop it ... I'm not saying they are gay ... and no more thoughts about tugging either!).
9 Inserting the crimps. Bear in mind the retention flap on the pins needs to be the correct way round for both plugs and (chassis) sockets. On plugs, the flap is facing outwards away from the centre spindle on both sides (cct 1-16 and 17-32) and on sockets, they face towards the centre.
Start from the bottom near the cable exit to load the wires. Insert cct 17-24 (or 25-32 if loading the whole DL) and bear in mind the retention flap is facing the correct way. Also, have a careful look at the connector labelling to make sure you don't load it upside down. I did this recently and I should know better after 32 years but the writing on the DL's has got smaller over the last few decades.
Close up picture of 17-24 loaded.
10 Insert cct 9-16. You now have 17-24 fitted so 9-16 just get loaded above them and keeps the view clear. These are somewhat more difficult though as they are scattered around the centre area. Be careful.
11 Insert cct 1-8. These should be easy to load as they are in a row without the more complex loading around the centre area plus you are at the end of loading a DL and should be more relaxed by now!
In point 1.2, I mentioned that the wires could have a chance to be orientated properly. You can see from this picture that some wires cross over each other to get into the right place!
Looks like I have cut off the lacing twine! Perhaps that is because it keeps the budge near the multicore insulation fairly small and the connector has already been loaded so, no need to keep them separated.
Close up picture of the 24 circuits fully loaded. Nearly there!
12 The black sheathing was resting further back on the cable insulation up to this point to keep it out of the way whilst I dealt with the 24 circuits (see point 2). Now, move it into place onto the 24 wires as shown.
13 I now secure the sheathing into the DL with lacing twine and then apply tape over it. Orientate the loom to exit the backshell out of the rear or at a right angle. I don't use heatshrink at the DL end because:
1 There is no need in my view.
2 It makes servicing hard to deal with.
3 Most console installations are a one off fit lasting 5-10 years or so therefore, once fitted, most DL's will probably not be tampered with for years.
14 Secure backshell lightly by fitting two screws. Unscrew the cable clamp and fit the backshell making sure that the loom is pushed into it a bit to allow some slack within the shell. The rear clamp takes the strain.
15 Fit the handle and covering plate. Test the whole loom if possible and only then:
1 Fit the last two screws
2 Secure the sheathing at the multicore end and tape if required.
3 Apply a heatgun to the heatshrink at the multicore end.
Bear in mind that you may need to take the DL apart to some extent if there is a fault (hence my suggestions above).
I hope this proves useful as it has taken many hours to finally present this post (nearly 50 pictures, photobucket uploads, draft forum posts etc). This is just my method of constructing a 24 circuit DL plug and I realise that everyone has their own opinions. Hardly anyone uses the black sheathing shown and most people use heatshrink these days it seems. I would argue that rubber sleeving for individual circuits is better but that debate can wait. My methods are based on practical experience over 30 years especially if confronted with a quick fix repair after a wiring company has permanently heatshrunk everything in sight and doesn't have to deal with the consequences!
Must go and get some din dins (or an early breakfast) as it is 3 am. More lengthy wiring posts from me fairly soon when I recover from this one!
Finally, I attach a blank DL plug wiring layout for your own use.
Regards from Jim Lassen (www.profcon.co.uk). Also on Facebook FACEBOOK
marcmozart:
Hall of Fame-Post!!! I just wired my first (prototype)-DL yesterday and 12 hours later here are all the answers to yesterdays questions... :)
sintech:
Jim, it's pure art to my eye, thanks for sharing.
marcmozart:
Jim,
thanks again - here's proof I'm officially using the Jim L-method. Still on a learning curve though, but my first 24 circuit D-Sub to DL plug is actually working beautifully and already delivering sound into my G-Series!
jimlfixit:
Hi Marc. Thanks for replying. I saw your picture and wondered what cable are you using? It is a standard type colour code judging from the colours but I can't be sure what make it is. What type of strippers are you using for this? Did you see the red Stripmaster version I showed in my DL post?
Be careful stripping the black insulation off the balanced circuits as it looks like you may be in danger of accidentally cutting into the core wires. Also, why have about a 40mm length of heatshrink on there? Surely, you only need enough to cover the circuit and core wires plus screen. Maybe 20 or 25 should be enough.
Heatshrink is okay but less flexible than rubber sleeving especially if used in a small area like a DL connector although it has a smaller diameter. I have mentioned advantages and disadvantages for both in one of my wiring posts about patchbays I think.
I'm about to wire some DL's to PT 25 way D connectors so, will take pictures, document and post something in the wiring menu soon.
Hope this helps for now and regards from Jim Lassen (www.profcon.co.uk).Also on FACEBOOK
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