killswtch's Home Automation and Media Projects
This is the story of my attempts at integrating various technologies into a 3-bed semi, constructing as much of the hardware and electronics as possible myself.
Tuesday 15 January 2008, 9:47 PM
Resurrecting a dead amplifier - the continuation
At the end of last year I tested the prototype of the matrix audio switcher, in the process blowing up part of the amplifier that powers the speakers in the living room. After investigating the damage, I found a great site to buy the replacement parts from. They arrived before Christmas, but I didn’t get around to installing them until recently.
The new transistors are exactly the same as the dead ones, so it was just a matter of unsoldering the old ones and replacing them. The nice chunky pads (compared to all the SMD boards I’m used to handling as computer parts) were lovely to work with, and the work was done in a matter of minutes. Minutes + £6 of parts = one big saving over a new amplifier and a lot of waste electronics. If only all devices were this easy to fault-find and fix.
With a fire extinguisher at the ready and my adrenaline gland just waiting to explode, I switched on the repaired circuit and ….. near silence, just the sound of the fan - it worked! Now that both channels are actually wired to something rather than one of them shorting out, the sound coming out is pretty good. In a few months the whole system should be up and running.
PreviousComments on this post
Ah, good old-fashioned through-hole electronics and TO-220 packages with holes blown in the side! You don't get much more retro than that - well, unless you want to get all thermionic.
I remember fixing many stereo amps (and music centres. Remember them?) back in the days when brushed aluminium fascias and fake wooden end-cheeks were all the rage. I never did work out why so many designers bothered putting in PCB fuses in the speaker circuits - either the two-ended fuse was fine and the three-legged fuses had blown, or Joe Punter had 'fixed' the previous short by wrapping the foil from a packet of John Player Specials around the dead fuse and replacing it.
