monkeypuzzle Posted March 3, 2009 Share Posted March 3, 2009 Just a quick one, I have an atomic that seems to be rather unhappy, fuse is fine and the thermo trip is fine. There are however two resistors that have burnt out, R139 and R183. they are 2r2 and on the schematic, it says Fusible PR01. has anyone else experienced this? If I replace the resistors, could there be any probs further along the line that may have caused this that I need to be aware of? What does Fusible PR01 mean? Cheers. Matt Link to comment Share on other sites More sharing options...
j_b Posted March 3, 2009 Share Posted March 3, 2009 Maybe http://www.vishay.com/docs/28729/28729.pdf? Link to comment Share on other sites More sharing options...
monkeypuzzle Posted March 3, 2009 Author Share Posted March 3, 2009 cheers, just got some from maplin and will see how long they last, may mount them away from the board to help heat dissperse but I reckon the vishay route may be the one... Link to comment Share on other sites More sharing options...
dirkenstein Posted March 3, 2009 Share Posted March 3, 2009 cheers, just got some from maplin..Oh dear :D Unless I'm very much mistaken (and Maplin has started selling flameproof/fusible resistors in the last 5 minutes), you may have just replaced a safety-critical component in your Atomic with an inadequate substitute. Flameproof/fusible resistors are usually used where upstream components can fail short-circuit (usually semiconductors or coils of some sort) and cause the resistor to dissipate many times their nominal power rating. Flameproof resistors have both a flame-retardant outer lacquer coating and a specified maximum power disspation (usually a value like 16x nominal power rating) at which they reliably fail open-circuit. If you overload a normal resistor in the same way, this may cause the resistor to eventually fail open-circuit after causing additional thermal damage, fail short-circuit, or worst case, cause the resistor's outer lacquer coating to catch fire. Even if the replacement resistor survives, or just fails open cicuit after charring, other upstream components may fry in various reasonably unpleasant ways. You may of course have uprated the resistors to a higher than specified wattage (not sure what PR01 stands for, but I'm going to guess 1W). Doing that may just cause it to burn the PCB instead when it gets hot, or cause some upstream component to burn out instead. Please check with Martin and any schematics/service manuals you have whether these resistors really are critical. Otherwise you may wish to have a fire extinguisher standing by when you test your strobe. Preferably _not_ at your next gig. I don't think the Vishay ones suggested are fusible either, although they do have a flameproof lacquer coating. Here's some possibly usable ones, but please check the power rating. Tyco Fusible Resistors from RS Link to comment Share on other sites More sharing options...
andylights Posted March 3, 2009 Share Posted March 3, 2009 FYI There was a well known problem on some early Atomics, which resulted with burnt out resistor(s). Bad times.... However I am not a service technician, so I can not say if this is what your specific problem is. But, replacement restored normal service. Good times.... Perhaps a call to the very helpful Martin Service Dept' to confirm? HTH Andy Also this thread... Good old search... Link to comment Share on other sites More sharing options...
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