Who Can Repair My Mach 460 Amps
Sometimes you get lucky.
My friend Jeremy has a 1995 Mustang that had the factory premium sound arrangement in it when he bought the car used. The CD role player was broken and he had the head unit of measurement replaced within a couple of weeks of owning the car. He later added a subwoofer.
I've always thought the stereo lacked clarity in the bass, and the head unit and EQ take had some quirks. Recently Jeremy pulled the head unit and institute all sorts of interesting techniques used past the aftermarket installer that volition be the bailiwick of a later monologue … but one of the things we discovered is that the amplifier for the door woofers wasn't working at all. Swapping information technology with the amp for the rear deck woofers caused them to go silent and the (shot) door woofers to piece of work once again (after resoldering their cut cables).
Turned out to be a delightfully easy fix.
The black connector on the bottom is input and the grayness connector on top is power in and speaker out. Although both connectors are pinned for two channels, only one channel is actually connected — this is a mono amp. Interestingly, all of the audio interconnects in the manufacturing plant sound organization are counterbalanced, which should assistance cutting out alternator noise and clicks and pops from other electrical systems — a luxury neither of us has seen in aftermarket sound systems.
When outset I opened the unit of measurement, I was disappointed not to discover whatever smoked components. Since we got no output whatsoever, I really expected to detect a melted power transistor or something else dramatic.
However, it didn't take long to discover the dramatically cracked solder articulation on this atomic number 82,
which turned out to exist the inductor in the pi filter on the power input,
so named because of the schematic's resemblance to the letter π (my favorite vitamin).
I wanted to exist sure to become all oxidation and clay out of the joint; and so instead of merely reheating information technology and adding more (flux-core) solder, I scraped both the pad and the lead clean with a chisel tip. While doing and then, I noticed that the whole inductor felt loose and discovered the less visually obvious second cracked solder joint.
My cess is that the inductor was installed somewhat carelessly at the factory and left sitting slightly above the PCB. Lacking contact with the board to prevent downwardly motion, a decade (or maybe less than a year) of vibration from the rear finish of a sporty coupe with a tight intermission broke the solder joints, thereby breaking delivery of power and disabling the whole amp.
After cleaning both joints, I reinstalled the inductor, this fourth dimension installing information technology flush to the board besides as bending the leads over for increased contact surface area earlier resoldering, in hopes of increasing the mechanical strength of the joints.
The capacitors to the left were already hot-glued in place to prevent damage from vibration, and before reassembling the amp, I glued down the whole pi filter.
I got in impact with Jeremy to let him know exactly how lucky he was, and last night we reinstalled the repaired amp and confirmed that information technology now works completely.
Credits
Cheers to flemworld.com for providing the name of the factory sound system, as well as wiring diagrams invaluable in the larger project but not direct relevant to this repair.
Source: http://www.neufeld.newton.ks.us/electronics/?p=1162
Posted by: anthonymadmon.blogspot.com
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