Mini Converter power clamp
A strain relief for the 12 V lead on Blackmagic's Mini Converter DAs and sync generator, so a tug on the lead pulls on a cable tie instead of the jack.
What it does
The SDI Distribution, its 4K sibling and the Sync Generator all take their 12 V through a plain barrel socket in one corner of a BNC end. It has no latch, so the only thing keeping a DA powered mid-show is friction and good luck.
This clamp takes the two case screws on the jack's side. From that arm a spine runs out beside the plug, with a floor under it, to a block just past the plug's moulding. You tie the cable into a groove in the block, on the jack's own axis, and from then on a pull on the lead stops at the tie.
Everything stays on the jack's outer side and below the plug. On the Sync Generator the nearest REF OUT is only 12.3 mm from the jack, so there's no room for anything between the two plugs. The clamp is flush with the case's top and underside, so the converter still sits flat. For something shorter that covers the whole end, see the Mini Converter power guard.
Where it stands
v0.1. I've modelled it and checked it in software, but I haven't yet printed one and fitted it to a real converter. The steps below are written from the model, and every number for the converter comes from Blackmagic's pictures. Once one has been on a real one, I'll update this page with anything that turned out differently.
Print your own
Fitting it
You'll need
- A Phillips screwdriver
- Two M3 countersunk screws, each 2 mm longer than the side screws you take out
- One cable tie, up to 5 mm wide and 1.5 mm thick. A reusable one with a release tab is kinder to hire stock than one you have to cut off
Check the longer screws fit before the clamp goes on. Nothing shows what's behind the side screws, and a screw that's too long could foul something inside the case. Step 2 checks it.
Do this with the converter unpowered.
- Take out the two side screws on the jack's side: the side nearest the POWER +12V socket. Leave the other side's pair alone; they hold the cover on meanwhile.
- Run one of the longer screws into an empty hole on its own, without the clamp. It should go all the way home without forcing. If it stops short, don't force it: put the originals back and let me know.
- Hold the clamp to the case: the arm flat on that side, flush with the top and the underside, and the spine's back against the case's front edge at the corner. Put a longer screw through each slot, and push the clamp towards the power end while you tighten them. Snug is enough.
- Plug the 12 V lead in, down the channel.
- Lay the cable in the groove in the block. From the outer face, push the cable tie in through one tunnel, round the cable and back out through the other, and close it on the outer face.
- Pull the tie snug, not tight: it only has to stop the cable sliding. Leave the cable a little slack between the plug and the block.
How it holds
A pull on the lead stops at the tie, the tie pulls on the block, and the block pulls on the case's two screws. The groove holds a 4.5 mm cable on the jack's axis, so the tie doesn't drag the plug off line either. The screw holes are slots, ±1.5 mm along the case and ±0.6 mm up and down, so the clamp can sit on the case's edge wherever the screws actually turn out to be.
The screws
Blackmagic's manual calls the side screws M3 Phillips, two each side. In Blackmagic's renders the heads sit flush, so I've taken them to be countersunk. I haven't had one apart to check.
The arm is 2 mm thick and its countersinks sit an M3 flat head just under flush, hence screws exactly 2 mm longer. Don't reuse the originals: they'd lose 2 mm of thread.
The BNCs next door
On the Sync Generator the REF OUT nearest the jack is 12.3 mm from it, centre to centre, so a BNC plug there comes within about 5 mm of the jack's axis. The clamp keeps out of its way, with at least 1.2 mm to spare.
The 12 V plug is another matter. On the Sync Generator, a plug moulding much more than 10 mm across will rub a BNC plug in that REF OUT, clamp or no clamp.
The case is shorter than it says
Blackmagic's drawings give the SDI Distribution as 4.80 in long, and retailers turn that into 123 mm. That's with the BNCs. The case itself is about 97 mm, which matters here because the screws sit a quarter and three quarters of the way along it.
Will your leads fit?
| 12 V plug moulding | Up to 13 mm across, centred on the jack |
|---|---|
| Moulding length | Up to 40 mm from the case's edge, boot included |
| Cable diameter | 3.5 to 6 mm (4.5 mm sits on the jack's axis) |
| Cable tie | Up to 5 × 1.5 mm |
Blackmagic's current supply has a 5.5 × 2.5 mm plug with a knurled locking collar about 10.4 mm across, which fits. On these plain jacks the collar doesn't lock anything.
Taking it off
- Release or cut the cable tie and unplug the 12 V lead.
- With the converter unpowered, take out the two longer screws and lift the clamp off.
- Put the original screws back in.
What's been checked
In software only, against the model. Nothing here has been tried on a real part yet, which is what the second list is for.
in software Flush with the case's top and underside, nothing inside the case, and the arm 0.2 mm clear of its side.
in software A plug moulding 13 mm across and 40 mm long fits the channel.
in software A BNC plug in the nearest BNC is clear with the BNCs anywhere from 10.9 to 13.9 mm up: on the Sync Generator with at least 1.2 mm to spare, on the DAs 5.5 mm.
in software Cables from 3.5 to 6 mm lie in the groove within 0.8 mm of the jack's axis. Both tie tunnels are clear, and a screwdriver reaches each screw.
not yet Where the side screws really are, and whether screws 2 mm longer go fully home.
not yet The jack's exact position, and the BNCs' height, which Blackmagic's pictures don't settle.
not yet Whether your 12 V lead's moulding fits the channel and finishes before the block.
Where the numbers came from
Written from scratch: nobody had published a part for these converters. Blackmagic doesn't publish drawings with port positions, so everything was measured off their product renders and top views, and a close-up of a Mini Converter end taken nearly straight on. The DA's and the Sync Generator's renders agree on the screws to 0.15 mm and on the jack to 0.2 mm.
More views
Fitted one?
Tell me how it went
If you've put one on a real converter, I'd like to hear about it, good or bad: whether it seated, whether your plug went in, and anything that got in the way.