Guess what I found in the gutter in Erskineville. Yes the gutter. In the rain. I thought “now here’s a challenge!”

After dragging it home and powering it up, I saw that the panel would light up, the buttons seemed to work but there was no sound coming out so I opened it up. It was certainly a mess inside (and out). It was filthy with mud and it looked like some cockroaches had been breeding in it. Fortunately, there was very little corrosion on the circuitry so I felt I had a good chance of getting it going.

First thing I did was to take it completely apart and wash all the plastic parts such as the case, buttons and keys with lots of hot soapy water.

After reassembling it, I had a poke around. By connecting some headphones to a wire and probing around the circuit board, I could work out that the sound was being generated but didn’t make it past the main amplifier chip, an LA4558, it seemed to be blown. I had a look through some parts suppliers catalogues but could not locate a replacement for this chip.

No matter because I had a stereo amplifier module surplus from an old project. I got this amplifier ages ago from WES just down the road at Ashfield for about $12 from memory. It is a 5W RMS per side, class A stereo amp. Total overkill for this job but what the hey. I simply bypassed the blown-up chip and fed the signal through the amp module. It has a little hiss, no doubt due to my sloppy wiring or incorrect impedance matching but is really loud when you crank it up.

I screwed the amplifier module down to the metal keyboard frame which makes a handy-dandy heatsink and it is good to go. Not bad for a couple of hours work, a free Kawai MS710 keyboard/synth! Maybe I could circuit-bend it in the future, we’ll see but for now, it makes a great toy for my kids.