IRW Posted October 4, 2011 Share Posted October 4, 2011 Afternoon All, In the venue that I have recently taken over, there were previously 60-channels worth of Permus dimming (Two 24-way racks and a 12-way rack). At some point over the past few years, these have been removed from service and replaced with 48-channels worth of Chilli-dimmers. Due to the size of the venue, and the use it gets, I'm struggling with only 48 channels (all hardwired). I've uploaded the plan I have drawn of the venue as it is currently here. Have a look at it and you'll see why I'm stuggling FOH. The red lines are all IWBs, and the red numbers in circles on them are what dimmer number they are hardwired to. Even with a planned re-jigging of what circuits go where, without a patchbay I'm still only on 9 circuits on FOH1 and 10 on FOH2. And so to my point...The old permus racks are still here in a corner of the electrics intake room, having been disconnected from everything. Two of them (1 and 2 below) have had a fair amount of stripping down done on them, but #3 looks pretty much intact. I'd prefer not to have to 'get a man in' as I am pretty nifty on the old maintenance side of things and we do have site sparkies, but Permus racks are a bit before my professional time, so, obviously with the usual 'danger danger, high voltage!' caveats, can anyone advise on the best way to see if #3 is still working/in a useable condition? With new 24-channel racks potentially costing upwards of £2K, it seems a waste not to use what I have! Photos: 1.http://www.irwdesign.com/br/permus1.JPG2.http://www.irwdesign.com/br/permus2.JPG3.http://www.irwdesign.com/br/permus3.JPG Thanks, Ian Link to comment Share on other sites More sharing options...
Ynot Posted October 4, 2011 Share Posted October 4, 2011 It's been a while since I delved into it but we have a wired and working 24-way Permus in our place that you're welcome to come take a gander at if you wish. None too far from you down the A5. I do need to get into it at some stage as we do have a couple of faulty channels to repair. Link to comment Share on other sites More sharing options...
oilyspark Posted October 4, 2011 Share Posted October 4, 2011 It looks as though the outgoing circuits of No.3 have just been chopped and the rack pulled off the wall. I'd take a punt on it if it were mine, detach all redundant cabling, do a quick check for shorts from the live side to the LV and casing, and stick a 13A plug on the incoming terminals. I can't remember the actual earth leakage current per channel but a 24ch rack might generate more than an individual portable appliance really should send back down a 13A plug, so you might prefer to hard-wire it in to a convenient circuit perhaps a fused spur, enough to power one channel at a time. You can test each channel in seconds with a 9V battery from control common to the channel input and any old light on the output. The good thing about these old analogue racks is that there is hardly anything common to more than a couple of channels, hence total failure is almost unknown. Negative points include the fact you will never get the dimming curve to track the Chillis exactly, so you would get slightly different results if you were (say) to do a sunset with some cyc channels on each of the two types of dimmer as compared to all on one type or another. You will need to equip yourself with a stock of Pullcap MD fuses, that aren't the cheapest these days. Finally, I don't see the demux inside, but I'm guessing you are running the Chillis from DMX so that will need to be connected up in the final scheme of things. We have a couple of installations with the Permus' predecessor (STM) running alongside Chillis, although I suppose those are now starting to reach the end of their working lives. The Permus still has a few more years to go to catch up! E2A: Re your 'Danger! Danger!' comment, don't forget that unlike more modern dimmers, older circuits with discrete thyristors have live heatsinks - those shiny ali bits are alternately connected to mains live / load / live / load so you have to be a bit more careful poking around inside! Lucien Link to comment Share on other sites More sharing options...
thetechguru Posted October 4, 2011 Share Posted October 4, 2011 Hi Ian If you need any spares Modules/ Capacitor cards etc Contact Audio Light Systems in Edinburgh. We have 2.5k and 5k modules and even the annoying little mounting pillers. Eddy Link to comment Share on other sites More sharing options...
topsy100 Posted October 4, 2011 Share Posted October 4, 2011 There are a few decent dimmer racks on fleabay that might be a cheaper option rather than getting the old permus racks up and running.... just a thought. Link to comment Share on other sites More sharing options...
mutley Posted October 4, 2011 Share Posted October 4, 2011 If they have the same mains capacitors in them as the Tempus dimmers, replace them all, unless you want to play to "RCD/MCB trip" lottery! They are prone to rupture, spewing their foily guts and the magic smoke, just when you least want it to happen! http://www.hp9845.net/9845/tutorials/preparations/images/epoxy-capacitors.jpg Replace them with decent X or Y rated capacitors (depending on their use) Link to comment Share on other sites More sharing options...
IRW Posted October 5, 2011 Author Share Posted October 5, 2011 Thanks for all input so far, and especially for the heads up on the live heatsinks- it becomes obvious when you look closely! I've got a few more questions specifically about the module pcbs now... Cue photo: http://www.irwdesign.com/br/permuspcb.JPGRank Strand PCB810 Mutley, do you know which the caps are that you are refering to? Is there a way to tell factory fitted ones? Also, there seems to be a bit(read: enought to concern me!) of blackening on the reverse of the PCB behind the two red diodes (in the middle labled D4 and D8, D8 in the shadow of TRX2) as if these have been getting exceptionally hot: http://www.irwdesign.com/br/permuspcb2.JPG Can anyone who is familiar with these say whether this is to be expected? It doesn't seem to me like an intended feature! I've only had a look at the one board so far, so don't know whether this is common to the rest. In reponse to the demux question, I have a couple of spare demuxes floating round from when these dimmers where in operation, so no worries there! I'm also not especially concerned about the dimmer curve, I'd just be happy to get some more channels! Thanks, Ian Link to comment Share on other sites More sharing options...
mutley Posted October 5, 2011 Share Posted October 5, 2011 There are no "kamikazi capacitors" on that board. The two hot diodes look like they might be voltage regulating zener diodes, working in conjunction with the resistor and transistor next to each one (VT4 & VT5). Read the number off them and Google it to check. If you want to replace them, they cost about 5p each from CPC! Link to comment Share on other sites More sharing options...
boatman Posted October 5, 2011 Share Posted October 5, 2011 The Permus dimmer module design is based on the old Tempus range. There is a Tempus service manual which can de downloaded on the Strand Archive Tempus page, but I don't know how closely they are related. An email to jon@strandarchive.co.uk might reveal more. As Mutley says, the hot diodes are probably Zeners. You can always fit larger ones with a higher dissipation rating (same voltage) and stand them off the board a little. Edited for SPaG. Link to comment Share on other sites More sharing options...
IRW Posted October 5, 2011 Author Share Posted October 5, 2011 Thanks chaps, this is looking hopeful! Ian Link to comment Share on other sites More sharing options...
thetechguru Posted October 5, 2011 Share Posted October 5, 2011 Hi Ian The burning on the board was a problem with early permus cards and rectified by Strand where ever it was identified. If our Strand Service engineer can remember I will post the mod later but I think it is a substantially larger rated zener as others have suggested. On the Exploding caps - they are not the same as the old X units and are not on the individual cards but on a large PCB towards the top of the dimmer. Eddy Link to comment Share on other sites More sharing options...
Richard P-W Posted October 6, 2011 Share Posted October 6, 2011 I'm currently delving into a set of Tempus racks, some boards have the capacitors that go pop and some don't! There's a mix of PCB810/2 which don't (Like Ian's) and 810/5 which have one between the two white leads on the board. They are actually a "snubber", consisting of a capacitor and resistor in series, used to protect the thyristors from switching spikes. I have 16 that have either bulged, split or departed from the board permanently. The other capacitors in a Tempus (and probably a Permus - but I've never had to work on one) are indeed on a separate board and connected phase - earth and neutral - earth for each output. These have already been replaced in this set of racks and had also been disconnected (before my time) but will be getting reconnected as it's likely this is what caused the snubbers to pop. Link to comment Share on other sites More sharing options...
IRW Posted October 6, 2011 Author Share Posted October 6, 2011 Righty-ho, I've got a few capacitor board photos, I take it these (and the board out of shot, but just below these) are the potentially suicidal caps?: Rank Strand PCB783/1 - REF 1294 - Permus RFI Cardhttp://www.irwdesign.com/br/caps1.JPG http://www.irwdesign.com/br/caps2.JPG http://www.irwdesign.com/br/caps3.JPG They all look in pretty good condition, no bulging or missing ones, and this is the same of all five boards throughout the three packs. Once again, thanks for all the help with these! There is a lot of useful information coming out and I hope that others still running Permus racks may find it helpful as well! Infact I may even head over to the wiki and stick a link in! Ian Link to comment Share on other sites More sharing options...
mutley Posted October 6, 2011 Share Posted October 6, 2011 Those are normally fine. The problem caps look exactly like the ones in the picture I posted: clear yellowish epoxy casing with the foil roll visible inside - and quite often spewing their guts out! On the Tempus packs, they go on a narrow (about 2" wide) PCB between the two rows of sockets on the front, but maybe they were only fitted for a limited time before they used decent ones?.... And if you want some spare dimming boards, I've just noticed this listing on ebay. Link to comment Share on other sites More sharing options...
musht Posted October 6, 2011 Share Posted October 6, 2011 http://www.irwdesign.com/br/permuspcb.JPGRank Strand PCB810 Thanks, Ian Be tempted whilst changing the zeners to change out the electolytics as well, the big blue ones on the board, the electrolyte dries out and they create a bit of a snow storm when they go bang ;-) Link to comment Share on other sites More sharing options...
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