Guttersynth
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.
Ooooh I have the same keyboard :)
hi, did you bend the ms710 already? i want to bend mine too (very soon)so maybe we can exchange some bending spots
Nah, I haven’t done anything with this one. However I have bent wavetable synths before, the best thing to do with them is identify the data and address lines to the ROM and connect them to each other either through switches or pots.
hey! i just bought a ms710 but i cant get it to work.. does it require batteries in it work?
Nope, I’ve never put batteries in mine. Check the voltage and polarity of your power input.
I had a poke around mine today and had a bit of trouble finding bends…. you need really thin probes that I didn’t have.
I did find however that you can find a tempo pulse firing up the tempo LED and rig it up to a few other select switches on the board and it will sequence or step through the pattern and melody select matrix.
Pretty cool. Whole thing sounds nice distorted too.
Hi,
I have told a friend that I would look at his (non-working) piano.
It has the same LA4558 and it seems fried.
I have some TDA2030 (stereo amps) and I would like to bypass the amplifier like you did.
Did you cut out some pins of the LA4558 to remove it (electrically) from the printed circuit?
Thanks.
I desoldered it using a solder sucker. It takes a little skill. You could easily just cut all the pins off if you are intending to bypass it.