ekul1978 Posted December 15, 2015 Share Posted December 15, 2015 Hi guys, we have a second hand tecpro PS7111 Power supply that we use at work (school). The unit has worked fine up to now but tonight during our panto the power unit kept tripping off then coming back on. What I mean by this is the DC light on the front would dim, cutting comms then come back on to full brightness, then after a minute or so do exactly the same. I turned the unit off and on again after a short pause only to have it do the same thing after a few minutes of working properly. I've checked the plug and the internal wiring in case there was a loose connection but nothing. Does anyone have an idea what may be wrong with it? Got a few more shows this week to do so I could do with it back up and running asap. Thanks Luke Link to comment Share on other sites More sharing options...
timsabre Posted December 15, 2015 Share Posted December 15, 2015 Could it be a problem in the loop wiring - a dodgy cable on a beltpack that shorts as it is moved?Or does it do this when the PSU is not plugged into the loop? Link to comment Share on other sites More sharing options...
ekul1978 Posted December 15, 2015 Author Share Posted December 15, 2015 It happens when its in the loop - can check the cable tomorrow as its all wired in place. But again its been working fine, guess someone could have pulled a wire Link to comment Share on other sites More sharing options...
timsabre Posted December 15, 2015 Share Posted December 15, 2015 it does sound like a cable fault somewhere in the system. Get someone to go round wiggling while you watch the psu. Link to comment Share on other sites More sharing options...
ekul1978 Posted December 15, 2015 Author Share Posted December 15, 2015 Yeah - had he PSU running for over an hour now without the beltpacks attached and nothing yet. If it is the cable better dig out my soldering iron :) Link to comment Share on other sites More sharing options...
J Pearce Posted December 16, 2015 Share Posted December 16, 2015 I've also had a beltpack go down with a high load across the PSU (on a hire, so never investigated further than labelling it as dead and getting a spare out), so perhaps check the beltpacks as well as the cabling. I'd probably unplug all beltpacks/stations, breaking the loop as I went. Plug in PSU then work from the PSU, pluggin in branches/loops til the PSU is unhappy. If the cabling isn't at fault, then add beltpacks until the PSU goes, then you have the dodgy one. Boring and dull, but unlikely to fail. Link to comment Share on other sites More sharing options...
bruce Posted December 16, 2015 Share Posted December 16, 2015 Check the cabling, check the belt packs. Do a binary search to identify the culprit. I had a system with exactly the same symptoms as you. One of the nuts holding the xlr in place on a belt pack had come loose, and was rattling about inside the pack, shorting the pcb. Link to comment Share on other sites More sharing options...
ekul1978 Posted December 16, 2015 Author Share Posted December 16, 2015 Thanks - Ive just checked the cabling and none of it seems to be broken, will run a spare that I know is definitely working just to make sure and will check the beltpacks too. Thanks for the advice guys. Fingers crossed. Link to comment Share on other sites More sharing options...
ekul1978 Posted December 16, 2015 Author Share Posted December 16, 2015 Well I've checked all the beltpacks and they all seem fine - plugged the PSU back into a new loop using the same packs/headsets but new cables. It appears that as soon as I run two packs on the same line that's when the problems start. If I use all three individual lines it seems to work fine but again as soon as I plug in a second pack to any of the three lines - power loss. So I'm guessing its going to be a problem with the PSU itself powering multiple packs (I'm only using 4 - SL, SR, SFX, LX). Not really sure why but that's my best guess unless anyone else can think of something. Link to comment Share on other sites More sharing options...
timsabre Posted December 16, 2015 Share Posted December 16, 2015 The psu should be able to power 16 beltpacks across any combination of outputs. Sounds like either the PSU is faulty or one of the beltpacks is drawing a lot more power than it should be. Can you put a multimeter in circuit to measure the current draw when each beltpack is added? Link to comment Share on other sites More sharing options...
boatman Posted December 16, 2015 Share Posted December 16, 2015 If it helps the original BP1 and PSU schematics (c 1992 & 1989!) can be found here and here. I don't think they have changed much in 35 years, even the BP1 PCBs are still the old hand-drawn ones. Link to comment Share on other sites More sharing options...
ekul1978 Posted December 16, 2015 Author Share Posted December 16, 2015 Thanks Tim - I will give it a go this afternoon if I can track don't the site mulitmeter (refuse to use my tools at work anymore due to theft). Thanks for the diagrams boatman, if all else fails I can at least pass the PSU onto a friend with the diagrams to see if he can sort it. Link to comment Share on other sites More sharing options...
paulears Posted December 16, 2015 Share Posted December 16, 2015 If multiple lines work, then measure the resistance of the cables before you plug them in - I bet one is very different. Havfe you tried looping out all the packs and the adding them in one at a time? Link to comment Share on other sites More sharing options...
ekul1978 Posted December 17, 2015 Author Share Posted December 17, 2015 Not even had chance to test the cables etc - the PSU is doing it without anything being plugged in now so its got to be something inside. Link to comment Share on other sites More sharing options...
DrV Posted December 17, 2015 Share Posted December 17, 2015 In that case check that any 3 terminal regulators there might be inside are firmly bolted to their heatsinks. And of course check for dodgy joints on any high power resistors. Link to comment Share on other sites More sharing options...
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