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Author Topic: Step 1 in the Amp Repair for Dummies Book  (Read 2907 times)

Jack1962

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Step 1 in the Amp Repair for Dummies Book
« on: July 17, 2008, 09:15:48 PM »
I recently had a Peavey Stereo Chorus 400(The Beast) come in for repair, this amp did nothing. Step #1 visual inspection. The thing had this large steel wheels mounted on it it , If a amp has wheels it's being moved CHECK FOR LOOSE SOLDER JOINTS. I check this thing from input to speaker output before it dawned on to me to check the @#$%  solder joints. I have been doing this for more years than I care to talk about , so in short always check the basics. The loose solder joints where on those 4700uF caps that give you the -43(not 53) and +43 volts the power the power transistors.


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J M Fahey

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Re: Step 1 in the Amp Repair for Dummies Book
« Reply #1 on: July 18, 2008, 12:06:36 AM »
Dear Jack, I understand fully what you feel. Instrument amps not only get moved a lot , wheeled or not, but they also endure a lot o trips in the back of pickup trucks or regular cars, and even if they "live" in a rehearsal room, the music itself shakes them to death. Boards flex and develop almost invisible cracks, and all heavy components (specially big filter capacitors) eventually get loose. I have even have seen quite a few of them who crack solder and pull themselves from the board and even some &%$*^&%$ of them with pins *internally* cut or broken. On many humming/popping/oscillating/unstable amps I start by soldering a couple of good filter capacitors (even if they have some less capacitance than the original ones) and more often than not the problem is diagnosed in minutes. Really, as you say, that´s the "step one". Bye.