Trantec S4000 beltpack innards

[cedd]

Hi All

Has anyone got any experience opening up a Trantec S4000 (S4.5) beltpack?

I'm needing a cheap and cheerful hire rack. Mainly for schools work. Don't really want to be spending huge bucks on them, and don't want to be too gutted if they get damaged. There are some very affordable S4000 systems out there at the minute, and they should more than meet my needs. 

But.... I'm on 4 pin mini xlr's for all of my other systems, and it'd be really nice to have some commonality across my stock. I'm tempted to try and convert them. The S4.5's are on Lemo 0B. From what I can see the Lemo is a 9mm diameter hole, whereas 4 pin mini xlr is 11 or 12mm. I have access to a 3d printer and am reasonably adept at 3d design, so can come up with adapters, shims or whatever else is needed to (I think) do a reasonable job of the mechanical side of things. But having not seen a beltpack yet I'm not sure what's going on inside of one. 

Could do with knowing if that Lemo is pcb mount or panel mounted with flying leads (like the S5.3's are). The photos suggest to me that it's panel mount as there looks to be an external flange suggesting an internal nut. How much space have I got to play with on the inside? 

Any help much appreciated.

Chris 

[richardash1981]

I don't know about S4000 / S4.5 beltpacks, but if it's any help the similar-date and similar looking S3500 beltpack is a panel mount LEMO socket with flying leads to the PCB (it even has silk screen saying what they do!). There isn't much room inside however given the shape of the beltpack, and the fact the PCB runs alongside the connector body (there isn't a cut-out in that corner).
It's worth knowing that the 4 pins are functionally a bit different to most other beltpacks, in that you get ground, DC and two signal pins. One of the signal pins has a DC bias on it, so you can connect 2-wire electret mics to just that pin and ground, without needing a bias resistor in the plug. The other pin is free of DC voltage, but not AC coupled, and is the signal input for line / instrument and dynamic microphones. The hairy bit is that this input doesn't pass signal if any DC offset finds it's way onto the signal (you just get silence). This is different to the Shure beltpacks and most others where the signal input pin is AC coupled and can be pulled up to the DC bias pin voltage by external mic wiring without any problems.

The overall result is that I have two different wiring LEMO to 4-pin Mini XLR adaptors - one works with dynamic mics and 3-wire electrets, the other with (commoner) 2-wire electrets ...

[cedd]

Thanks Richard. Useful to know there isn't much space inside. May have to be an adapter cable. Was trying to avoid having to buy 20 LEMO's as they're not the cheapest (even if you buy direct). 

Been catching up on some of bigclive's videos as well and am going to give some of the rechargable pp3's with on board usb charging a go. Would need to experiment with RF noise from the buck/boost circuitry, but it's definitely worth an experiment. If they work then I'm even toying with drilling the case over where the usb connector falls so they're simple plug and play charging. Will have to see. 

Had spotted the odity with the Leno pinout. What they've done makes sense I guess, but is going to take some thought. I'd pretty much exclusively 2 wire cheap headsets (CPC etc). Some of my very cheap no brand Chinese ones have little attenuators that I've built in to the mini xlr, so will need to do some thinking on the impact to those. 

Thanks for your help. 

 

[richardash1981]

I'll be very interested in the USB-charge PP3 batteries. I run the S3500s on Vapex 9.6V PP3s. They do need a specificially 9.6V charger, but the runtime is good after using them (only about once a month) for several years now. https://www.componentshop.co.uk/9-6v-220mah-pp3-nimh-rechargeable-battery-9v-pp3-replacement-vapex.html

Re the LEMO input connectors, below are compatible ones which work have switched to, and don't seem to have trouble with:

https://www.gigatronix.co.uk/push-pull-connectors/browse/0b-push-pull-series/straight-plug

I understand Gigatronix can't call them LEMO connectors because that's a trademark, but they can't be stopped from making compatible connectors as the design is old enough not to be under patent etc. any more.

[DrV]

P.M. sent

 

[cedd]

Thanks everyone. Apologies for the delayed response. 1 1/2 year old has covid and it's been a very snotty and unpleasant week! 

I've just ordered 6 channels to play with. Going to open a transmitter up and see what options I've got. The aim is to have 20 channels in total eventually. Most of my school hires are 16 channels but I always like to send some spares. Buying a separate set of cheap headsets on Lemo isn't the end of the world if needs be. Though cross compatibility would be great too. 

Will let you know how I get on. 

[J Pearce]

We have a small stash of Lemo to threaded 3.5mm adapters so that we can use the cheap CPC headsets with our Senn 2000s (reterminating the CPC headsets to Lemo would double their value...)

They work fine, the tail of the adapter can be a little awkward, but we tend to use the CPC headsets for corporate style events, they wouldn't be appearing on one of our musicals.

The same seller has what you appear to need - might be worth playing with before committing to hacking the packs apart?

Edited July 12, 2022 by J Pearce
amended second link