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k200b1 keeps blowing fuses [message #11705] Sun, 30 August 2009 18:39 JLElectric Messages: 12 Registered: August 2009 Location: Holly Ridge, NC Junior Member k200b1 keeps blowing the fuse by the on/off switch. I install 2 eminence 8 ohm 15's in cabinet, it played great for about thirty min. Then keeps blowing fuses. The amp hasnt been used in a while. Is there an easy fix? Report message to a moderator

Re: k200b1 keeps blowing fuses [message #11706 is a reply to message #11705] Mon, 31 August 2009 06:10   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member If a 3 amp fuse keeps blowing, or even a 2 amp fuse with no signal going thru the amp you have one of two problems, and if you have a volt meter you can pin down which of the two it is. If you have a volt meter, set it for low DC volts if its a analog type( like 100 volts or less) and hook it up across the end of your speaker cable plug, replace the fuse one more time and turn the amp on, if you see the volatge reading jump up to 5 volts or more before the fuse blows again than the amp has a blown output stage. If you see no major DC blip, than chances may be pretty good that just the rectifier bridge blew out which does not harm any other part of the amp but the fuse, and cost all of 5 bucks at Radio shack. Let us know if you need more help! Report message to a moderator

Re: k200b1 keeps blowing fuses [message #11707 is a reply to message #11706] Mon, 31 August 2009 08:04 JLElectric Messages: 12 Registered: August 2009 Location: Holly Ridge, NC Junior Member i will try that. It blows as soon as i flip the switch but maybe i can tell. What is the part called from radioshack. Im gonna go ahead and pick it up. Thanks for the help. Im sure i will have more questions. Report message to a moderator

Re: k200b1 keeps blowing fuses [message #11709 is a reply to message #11705] Mon, 31 August 2009 11:59 chicagobill Messages: 2005 Registered: April 2003 Senior Member If the amp is instantly blowing the fuse, I doubt that you will be able to get an accurate voltmeter indication on the output jack. As Steve noted, there are two main causes for your problem. One is a shorted output transistor, and the other is a shorted rectifier in the power supply. There can be other causes, but these are the two usual suspects. You can just replace parts with the hope that you will find the right one, or you can troubleshoot the circuit to find your problem. Either way works. If you have a multimeter (especially one with a diode test function), you can check the outputs and the rectifiers before you start spending money on parts or additional fuses. If you don't have a meter, there are a couple of ways to find the problem, but it may take a few fuses to figure it out. Report message to a moderator

Re: k200b1 keeps blowing fuses [message #11710 is a reply to message #11705] Mon, 31 August 2009 12:13   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member Don`t rush out and buy that rectifier bridge just yet! heres a test you can maketo better pin down the fault. Mounted on the floor of the amp right next to the power transfomer is the round rectifier bridge diode( it converts AC coltage to DC that the amp runs on), its round, square if its been replaced. They both will have 4 wires on them, one red, two black off of the power transfomer, and one green goin to ground/the chassie, if you unplug or unsolder the red and green wire and the fuse then still blows, that will confirm that the bridge is good and you have a problem with the output stage. At that point, and judging by your post I do not think you have the knowlage to repair it yourself and it will be time to take the amp to a tech for repair of the output stage. Report message to a moderator

Re: k200b1 keeps blowing fuses [message #11711 is a reply to message #11710] Mon, 31 August 2009 12:36 JLElectric Messages: 12 Registered: August 2009 Location: Holly Ridge, NC Junior Member you are right, im lost. Im an electrician, but electronics is totally different. I will try that. I did try unplugging the output transistors before and it still blew. I will try the rectifier when i get home. Thanks Report message to a moderator

Re: k200b1 keeps blowing fuses [message #11715 is a reply to message #11705] Mon, 31 August 2009 16:25 JLElectric Messages: 12 Registered: August 2009 Location: Holly Ridge, NC Junior Member I unhooked the red and green on the rectifier and the fuse still blew quickly. Should I continue or take it somewhere? Could it be the transistors and drivers? Report message to a moderator

Re: k200b1 keeps blowing fuses [message #11716 is a reply to message #11715] Mon, 31 August 2009 17:47 chicagobill Messages: 2005 Registered: April 2003 Senior Member JLElectric: Try pulling off the two wires that go from the transformer to the rectifier, make sure that they are away from each other and anything else. Now if the fuse still blows, the transformer may be shorted. (It could also be a problem with the wiring.) If the fuse holds, then the rectifier is shorted and needs to be replaced. Steve: The green wire from the rectifier supplies the negative voltage bus and is not grounded. After pulling off the red and green wires, if the fuse still blows, it does not mean that the rectifier is ok. Just the opposite, it means that the problem lies in the rectifier or the power transformer. Report message to a moderator

Re: k200b1 keeps blowing fuses [message #11719 is a reply to message #11716] Mon, 31 August 2009 19:53 JLElectric Messages: 12 Registered: August 2009 Location: Holly Ridge, NC Junior Member i did what you said, it didnt blow. So I changed out the rectifier. I spoke with my father in law and he said it sounds like it did before. Lack of drive or power. He actually thought it was blown speakers before. So I changed the speakers. Now it just needs some power. Whats my next step. It sounds really distorted. Could it be transistors? Report message to a moderator

Re: k200b1 keeps blowing fuses [message #11720 is a reply to message #11719] Mon, 31 August 2009 19:53 JLElectric Messages: 12 Registered: August 2009 Location: Holly Ridge, NC Junior Member oh yeah, you were right. disconnected the two blacks and it worked. Report message to a moderator

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