mikebarber Posted January 9, 2020 Report Share Posted January 9, 2020 i'm about to put together a bunch of TC cables, and was wondering about ground. for example, the TC LEMO 5-pin pinout from the SD633 is: 1 = ground 2 = SMPTE TC in 3 = ASCII in/out 4 = tuning out 5 = SMPTE TC out so, using a single conductor cable, i'll connect LEMO pin 5 to the DIN conductor pin for my uni-directional cable for feeding TC from my SD633 to UltraSync One. but i'm wondering if it's necessary (or at least wise/best practice) to connect LEMO pin 1 to the cable shield for grounding? or is that totally unnecessary? Quote Link to comment Share on other sites More sharing options...
tourtelot Posted January 9, 2020 Report Share Posted January 9, 2020 Un-necessary. No benefit and no need to make soldering those connectors any harder than they already are. D. Quote Link to comment Share on other sites More sharing options...
Derek H Posted January 10, 2020 Report Share Posted January 10, 2020 I think yes it would be. To complete the circuit, no? TC can be treated like unbalanced audio. Sort of. Quote Link to comment Share on other sites More sharing options...
Charlie Parra Posted January 10, 2020 Report Share Posted January 10, 2020 Yes, you will need the ground signal to complete the circuit, as Derek has mentioned. Quote Link to comment Share on other sites More sharing options...
mikebarber Posted January 10, 2020 Author Report Share Posted January 10, 2020 hmmm, i made the cable last night before i saw the additional replies saying i do need to. fwiw, the cable works just fine without it, and appears that it's in fact not necessary. whether or not it's best practice is a different matter, but it works just fine without it. Quote Link to comment Share on other sites More sharing options...
Bouke Posted January 11, 2020 Report Share Posted January 11, 2020 eeh, measure the resistance between pin 1 and shield on the device. It should read zero, meaning, if you jack in the plug, it is connected. How hard is this? (Or I'm missing something...) Quote Link to comment Share on other sites More sharing options...
tourtelot Posted January 14, 2020 Report Share Posted January 14, 2020 And sorry, I thought the question involved attaching the shield to the connector shell. But you can't send any signal, balanced or not, on one wire. Pin 1 and Pin 5 on the Lemo to lo and hi on whatever connector feeds the Ultra Sync. Looks like an SMC? Gad, a different connector for TC. Ugh! Looks like the perfect application for my Camlock-to-SMC (TM) adapter. D. Quote Link to comment Share on other sites More sharing options...
mikebarber Posted January 15, 2020 Author Report Share Posted January 15, 2020 20 hours ago, tourtelot said: And sorry, I thought the question involved attaching the shield to the connector shell. that's a correct assumption, as the cable shield is mechanically connected on both the LEMO and DIN 1.0/2.3 via crimping. following the connector manufacturers' assembly instructions, and connecting LEMO pin 5 to the DIN conductor pin, i have exactly what i need for a uni-directional TC cable from the SD633 to UltraSync One. it worked perfectly in my testing and in the field over the weekend, so it's safe to say that it is NOT required to involve the LEMO's ground pin. Quote Link to comment Share on other sites More sharing options...
tourtelot Posted January 15, 2020 Report Share Posted January 15, 2020 That assumes that chassis ground and electronic ground are strapped together. Sometimes that is true and sometimes the two grounds are not connected and if Pin 1 on the Lemo is not connected, the cable will not work. I would always connect Pin 1 on the low side but see no need to connect the low side (shield probably) to the Lemo shell. In fact, in some situations, that would open the path for a ground loop and increase the possibility for putting T/C audio into your primary audio path. D. Quote Link to comment Share on other sites More sharing options...
Charlie Parra Posted January 15, 2020 Report Share Posted January 15, 2020 1 hour ago, tourtelot said: That assumes that chassis ground and electronic ground are strapped together. Sometimes that is true and sometimes the two grounds are not connected and if Pin 1 on the Lemo is not connected, the cable will not work. I would always connect Pin 1 on the low side but see no need to connect the low side (shield probably) to the Lemo shell. In fact, in some situations, that would open the path for a ground loop and increase the possibility for putting T/C audio into your primary audio path. D. Doug is correct on this...... Quote Link to comment Share on other sites More sharing options...
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