Radio Shack MD-4072 (Casio WK3200) - Mods
2012-05-21 by montequi
Hi, I don't know if this keyboard is particularly collectible. I bought it on eBay, and I actually like the color contrast better than the WK3200. I purchased it to replace a Roland JV-30 and a Voce Micro-B...and it's done both admirably, but there were a few things that bothered me about it, so I did the following: 1. These newer consumer-level Casios tend to have really light cheap-feeling action to the keys. So, I bought some self-stick wheel weights (used to balance car wheels), and I added weights to all the keys. I did find the a few of them fell off over time...so I reglued them with super-glue. If I ever do this to another keyboard, I'll do the super-glue at the beginning. 2. The keys were also very noisy (clicky), and the weights only made them noisier. To remedy this I bought some white lithium grease at Home Depot and generously greased up the keys (inside each key and the plastic it fits into). This quieted them down significantly. 3. I was used to having a footswitch to work the leslie on my Micro-B, but the Casio only had a button on the front panel. So, I took a chance and pulled out did some experiments on the circuit board. I found I could bridge to solder points to activate the modulation button/leslie. So, I soldered 2 wires to these points, soldered the other end to a 1/4" jack, and drilled a hole in the back of the keyboard (there was plenty of space). Now I can plug in a footswitch (the kind that's "ON" when it's down and "OFF" when it's up) and turn on and off the leslie. 4. When I had it open I happened to trace the wire coming from the bender and found 3 unused solder points on a circuit board. I decided to find out if this could be where the modulation knob connects on the higher models (WK3500,3700,3800). It turns out I was right. I was able to temporarily connect a potentiometer and work the modulation (which co-exists with the modulation button...almost like Casio planned it this way!!). I decided to add a stereo jack in the back for an expression pedal rather than adding a knob on the front...and I'm happy I did. Now I can work the variable DSP parameters (like the 'Wah' on the LFO) with my foot while playing!! 5. I also found the dampening on the keys was a bit hard, so I added a strip of rubber weather stripping in front of the felt under the keys. It gives it a nice soft feel when playing lightly. 6. I also added some cloth I with double-stick tape around the spots of the bender where the spring hits to quiet it down a bit. My other keyboards have much quieter benders, so I tried to duplicate that here. It's still the noisiest of the bunch, but it's much quieter than before. I have ideas how to make it quieter, but I'm getting tired of repeatedly opening up the keyboard...so maybe someday I'll do this. I don't use the bender much, so we'll see. So, anyway, I bought the keyboard for $100, and it now feels like one worth $1000. I LOVE the drawbar organ and the analog synth sounds. The sampler is also an amazing feature, and the ZPI chip has great reed and brass sounds. I found I could use the synth to improve the string sounds, and the pianos are really nice (although the samples are better on the newer Casios). All-in-all, I'm really happy with the result. If anyone here wants to try these mods (a lot of them are doable on other Casios), contact me. I'll send you instructions and tell you where you can get the materials you need.