Guest joewhite903 Posted March 10, 2008 Share Posted March 10, 2008 Hi all I’m rebuilding A Perma 12 Dimmer pack and I’m planning to update it a bit. As a few off the dimmer module transformers have gone and there are a number of other faults plus due to its age I have to rewire the whole unit. What I plan to do is, Firstly Clean and re-spray the casing, Then clean all PCB's. Then What I’m planning on doing is remove all low voltage transformers and have one local instead,There will be RCD breakers instead off fuses along with possible a MCB Havent 100% decided on that yet and I intend to install 2 Socopex sockets on the top off the case along with a 3 phase ceeform plug and build a 12ch DMX 2 analogue board inside, so it will be strand base but very modern rest. Anybody have any idea as to how much I should be able to sell the unit for when it’s finished, Everything will be to a very high standard and the unit will be tested and new manuals and service manuals will be created for it. Thanks Joe Link to comment Share on other sites More sharing options...
KevinE Posted March 10, 2008 Share Posted March 10, 2008 Dont the transformers rely on isolation between the channels? Link to comment Share on other sites More sharing options...
Guest joewhite903 Posted March 10, 2008 Share Posted March 10, 2008 Why do they rely on isolation, because ive had one of the whole modules apart and I cant see why it wouldn't work Link to comment Share on other sites More sharing options...
boatman Posted March 11, 2008 Share Posted March 11, 2008 Why do they rely on isolation, because ive had one of the whole modules apart and I cant see why it wouldn't work Mini 2 and Perma 12 racks are designed as three phase boxes, which can operate from single phase. Therefore they need separate low voltage supplies as galvanic isolation for the phases. Link to comment Share on other sites More sharing options...
Ynot Posted March 11, 2008 Share Posted March 11, 2008 Why do they rely on isolation, because ive had one of the whole modules apart and I cant see why it wouldn't work Mini 2 and Perma 12 racks are designed as three phase boxes, which can operate from single phase. Therefore they need separate low voltage supplies as galvanic isolation for the phases.Which leads me to suggest that if you're not 100% sure of what you're doing and why, then this isn't something you should be attempting...!Especially as you're talking about selling the thing on when you're done. Link to comment Share on other sites More sharing options...
boatman Posted March 11, 2008 Share Posted March 11, 2008 Unfortunately, by the time you've finished all your planned mods, it will be neither a new dimmer pack nor a piece of nicely restored theatrical history. As such it is unlikely to have a great deal of resale value. However, I'm sure you'll have fun doing the work and you'll learn something too. Link to comment Share on other sites More sharing options...
Guest joewhite903 Posted March 11, 2008 Share Posted March 11, 2008 Reason as to why im saying about the single psu is because I have a 6ch rack dimmer pack which can run 1 or 3 phase and there is only one low voltage psu inside and not 3, what I could then do is when I wire up the packs I could install 3 Transformer supplies one per phase as that is very easy to do, as to your Question Ynot, I have a hell off a lot off experince in what im doing I may only be 20 but I know a lot. Yes I may not know somethings but you only learn by asking. Link to comment Share on other sites More sharing options...
david.elsbury Posted March 11, 2008 Share Posted March 11, 2008 But how your 6 channel pack works is irrelevant if it's not a Strand Perma 12... they are unlikely to be built in the same way, so I'd suggest listening to other posters who actually know how this particular dimmer works... of course, if you'd prefer to have just the one supply and ignore the safety issues, feel free... just don't ask me to use it... Galvanic isolation is the principle of isolating functional sections of electric systems so that charge-carrying particles cannot move from one section to another, i.e. there is no electrical current flowing directly from one section to the next. Link to comment Share on other sites More sharing options...
Ynot Posted March 11, 2008 Share Posted March 11, 2008 as to your Question Ynot, I have a hell off a lot off experince in what im doing I may only be 20 but I know a lot. Yes I may not know somethings but you only learn by asking.Sorry if a nerve got touched there, Joe.I just remember (a LONG way back!) when I myself was just 20 years old and thought I knew 'a hell of a lot' but looking back I can see that I in fact knew very little, and to be frank some of the things I attempted with that naiivety were quite honestly not things I'd do today - when I know there is a lot I still don't know! So excuse me for advising caution.Especially when so many youngsters (compared to some of us here) are so obviously NOT experienced enough. <_< Link to comment Share on other sites More sharing options...
Tomo Posted March 11, 2008 Share Posted March 11, 2008 Reason as to why im saying about the single psu is because I have a 6ch rack dimmer pack which can run 1 or 3 phase and there is only one low voltage psu inside and not 3, what I could then do is when I wire up the packs I could install 3 Transformer supplies one per phase as that is very easy to do, as to your Question Ynot, I have a hell off a lot off experince in what im doing I may only be 20 but I know a lot. Yes I may not know somethings but you only learn by asking.This would be really funny if it weren't so terrifying. SCR/TRIAC-based dimmers are CONSIDERABLY more complex than you appear to think. The transformers are not (only) power supplies - they are used by the triac triggering circuitry to work out sync and zero-crossing.The precise behaviour of those transformers is very important - so much so that some dimmers (eg Sensor+) actually use FOUR transformers - one as a power supply and the remaining three for accurate mains phase sensing. So you cannot just swap out the transformer for anything you feel like - it has to be sufficiently similar to the original design as otherwise you'll get extremely odd dimming, probably complete with flickering. Some dimmers don't bother with galvanic isolation transformers and instead use dropper resistors to achieve the same end - these tend to be single-phase, although I can think of a couple of methodologies for doing this 3-phase. However, a dimmer designed for one method CANNOT be converted into the other method of phase detection without a significant redesign - essentially the only bits you'd keep would be the data reception circuitry and the triacs themselves. Link to comment Share on other sites More sharing options...
Guest joewhite903 Posted March 11, 2008 Share Posted March 11, 2008 Ok I think everyone is getting a little sidetracked here, All I asked was how much would I roughly get for it when it is finished and working properly and tested safe. everthing else I will find out along the way. Joe Link to comment Share on other sites More sharing options...
boatman Posted March 11, 2008 Share Posted March 11, 2008 Ok I think everyone is getting a little sidetracked here, All I asked was how much would I roughly get for it when it is finished and working properly and tested safe. everthing else I will find out along the way. Joe Yes, and I think I gave you the right answer. What you will have is a hybrid dimmer pack with no history and no traceability or reliability records. Essentially a home-made unit, which you might be lucky to sell on ebay for a few quid. You might be better to simply refurbish it as a museum piece, but don't get your hopes up too high. Link to comment Share on other sites More sharing options...
Guest joewhite903 Posted March 11, 2008 Share Posted March 11, 2008 Im looking to get about £800 for this when its finished ,I have no intentions on putting this anywhere near Ebay. Idea is use it for an instalation with the work. But would need to know how much to charge my boss for it. Link to comment Share on other sites More sharing options...
boatman Posted March 11, 2008 Share Posted March 11, 2008 Im looking to get about £800 for this when its finished ,I have no intentions on putting this anywhere near Ebay. Idea is use it for an instalation with the work. But would need to know how much to charge my boss for it. Stage Electrics will sell a pair of brand new Rack6s for only £110 more, complete with a manufacturers warranty. Unless your boss is a total greenhorn, he should have a better concept of value for money than that. Link to comment Share on other sites More sharing options...
Andrew C Posted March 11, 2008 Share Posted March 11, 2008 Sorry Joe. No hope; unless your boss is a clueless numpty with no idea of the real world... To put it in context, I bought 140 odd ways of second hand, working dimming (mixed Arri and Zero) for £1100. Link to comment Share on other sites More sharing options...
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