Pete Alcock Posted March 23, 2006 Share Posted March 23, 2006 I should say straight off that I've emailed Zero88 about this just now, but my need for info is very urgent and it would be asking a lot to expect an immediate response from them, so here goes... Channels 3 & 4 come on permanently, about 3 seconds after power is applied to the pack. Definitely not the triacs as the fault moves when I swap the outputs of the control PCB around. Have concluded it's something up with outputs 3 & 4 on the control PCB, to which I don't have any sort of schematic. Also it's not the 6-way test switch or any problems with the 0-10V inputs (have disconnected them all). Has anyone ever seen this before, and successfully fixed it? Alternatively, anyone got an extract of the circuit diagram they could share with me? Thanks as always. Pete. p.s. Tech run on Saturday, Full Dress on Sun. Contingency plan - try to hire a pack in with IEC outputs! Link to comment Share on other sites More sharing options...
Andrew C Posted March 23, 2006 Share Posted March 23, 2006 Common fault. There are 4 or 6 big power resistors in there, they are potential divider pairs (I think) and they die with regularity. Easy fix. ISTR answering the same question a long time ago, so a search may turn up more detail, though quite what terms you'd use to find the right thread on Beta packs is another question! Edit 2Strike me! I didn't know the values then either! But in the post below this one... Link to comment Share on other sites More sharing options...
johnhuson Posted March 23, 2006 Share Posted March 23, 2006 This is entirely from a distant memory of a similar problem I came across several years ago, so information may not be entirely correct! I seem to remeber it being something to do with some large resistors (rated around 1 Watt I believe) failing. There are three of them in total, one per pair of circuits hence the reason your seing the same problem on those two channels. Pretty sure they're located towards the end of the circuit board near the mains incomer posts. EDIT: Beaten too it again! Link to comment Share on other sites More sharing options...
Pete Alcock Posted March 23, 2006 Author Share Posted March 23, 2006 Andrew, John, A million thanks!!! Fantastic. 2, 100K resistors fitted and it works perfectly again. Both were open circuit. The Blue Room is a brilliant resource and I owe you guys beer. The show is saved and my sanity restored. Bless you, Pete. Link to comment Share on other sites More sharing options...
Nicktaylor Posted March 24, 2006 Share Posted March 24, 2006 Channels 3 & 4 come on permanently, about 3 seconds after power is applied to the pack. Definitely not the triacs as the fault moves when I swap the outputs of the control PCB around. Just so you know. This is an ageing problem with the resistors. We have and install of six of the beasts and they are ten years old. About five years ago we had a spate of failures like this and the same thing is happening now. I have a suspicion that a higher loading might cause the problem. An external user was in and since then we have had a spate of problems. Zero 88 tell me that the control side of 1 and 2 come straight from the PSU and therefore this fault never happens on those circuits. 3 and 4 , and 5 and 6 each run as a pair from circuits including the 100k resistors. Experience has shown me that a blown triac can also take out the resisitors. Always worth replacing the lot once you have gone as far as opening up the box! Editted to remove unnecessarily large quote. Please use the "add reply" button unless you specifically need to quote. Thanks. JSB Link to comment Share on other sites More sharing options...
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