Chazz Posted October 3, 2007 Share Posted October 3, 2007 My beloved Promedia system died recently. Turned it on one day and got a sound similar to a staticy heartbeat. I opened up the sub and found a couple resistors that looked burnt. The circuit board around them was also scorched. One looks like a regular resistor (tan body with spec stripes). The other is larger, grey and also has the spec stripes. What kind of resistor is this? I'm sorry about not posting their component positions (the sub is at home) but as I can't seem to find diagrams anywhere, I'm not sure it matters. The markings on the grey resistor indicate that it is a 19k ohm resistor with 0% tolerance. If a resistor or two have died, should I be worried that the IC's have been fried as well and that replacing the resistors will be a futile effort? Any help here would be much appreciated. Quote Link to comment Share on other sites More sharing options...
Chazz Posted October 4, 2007 Author Share Posted October 4, 2007 Update: The two burnt resistors are in positions R12 and R26. These are fairly well-known resistors-o-death from what I am picking up. The grey resistor was the R12 one. Can anyone tell me what I need to buy exactly for R12 and R26? R26 looks to be so badly scorched that I can not easily distinguish the color stripes on it. Quote Link to comment Share on other sites More sharing options...
Chazz Posted October 11, 2007 Author Share Posted October 11, 2007 Found the info from this old thread: http://forums.klipsch.com/forums/thread/849925.aspx Just to confirm that these parts are correct and will work....... R26: 47k R12: 680 I measured my working unit and R26 was 48k and R12 was 658 both of which are 5% from 47k and 680 This is my order from digikey. I sure hope these will work. I know 3 watt is large but hey atleast it wont burn out as fast. IndexQuantityPart NumberDescription Unit PriceUSD Extended PriceUSD 1 2 IRF740IR-ND MOSFET N-CH 400V 10A TO-220AB 3.37000 $6.74 2 5 BC47KW-3JCT-ND RES 47K OHM METAL FILM 3W 5% 0.54200 $2.71 3 5 PPC680W-3JCT-ND RES 680 OHM METAL FILM 3W 5% 0.41800 $2.09 Subtotal $11.54 Quote Link to comment Share on other sites More sharing options...
magnum29 Posted November 7, 2007 Share Posted November 7, 2007 Chazz, was your repair successful? Quote Link to comment Share on other sites More sharing options...
WatchDragon Posted March 21, 2008 Share Posted March 21, 2008 im digging up this thread, my R12 popped, but the path onthe board is blackened, not the resistor itself, the pathway isnt damaged at all, its jsut black, could this resistor be bad without showing any damage? Quote Link to comment Share on other sites More sharing options...
etjrowe Posted June 9, 2008 Share Posted June 9, 2008 Mine finally died too. R26 is open and R12 reads a little low and is severally scored. I'm going to go ahead and pic up the parts and solder them in at work (the Navy buys better equipment than I have). I will let everyone know if it fixes my problem. Quote Link to comment Share on other sites More sharing options...
etjrowe Posted June 9, 2008 Share Posted June 9, 2008 im digging up this thread, my R12 popped, but the path onthe board is blackened, not the resistor itself, the pathway isnt damaged at all, its jsut black, could this resistor be bad without showing any damage? Oh, and yes, the resistor can absolutly be bad without showing any external signs. In fact, it's pretty rare to be able to just look at most small components and tell if they are bad. R26 is completely open on my board, but barely looks scorched, R12 looks much worse and is barely out of tollerance. The scorcing is not what you should be concerned with. The majority of the scorcing and discolleration you will see on boards is caused by the plastic like protective coating that most boards are coated with simply heating up and changing color, or mildly scorcing. It's very rare for a foil run on the board to heat up enough to melt (have never seen it happen in all my years as a Navy electronics tech). I actually used to joke that I could tell about how old the circuits cards in some of the radios on the ship were due to their color. When I put them in the would be a nice bright shiny green, and a couple years later, dull brown.But those thing operated under some pretty rough conditions. I'm definatly going to try to modify the sub enclosure to disipate heat a little better, hopefully without making it sound like a wet fart. Quote Link to comment Share on other sites More sharing options...
MD1032 Posted August 8, 2008 Share Posted August 8, 2008 I've heard that some people actually put heat sinks and fans on the back of their subs to help dissapate the heat... probably a good idea, actually. I can't believe a resistor could heat up and just burn like that. Oh well, good thing they're cheap. While you're in there, might as well upgrade some of the components. Quote Link to comment Share on other sites More sharing options...
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