Today I bought 2 Roland A-33 Midi Keyboard controllers. They both have issues and therefore where very cheap. I might keep one if I can repair both of them because they have a nice 76 semi weighted keybed and some other features that make them cool 🙂
At home I tested what was wrong with them. The guy selling them said one had some issues with a couple of keys not being velocity sensitive anymore. Not really a problem, a good clean will fix that. The other one “only needs a little bit of soldering on the power connector thing”. I thought that the plug on the back to that A-33 would be broken but at first glance it looks fine.
It came with 2 wall wart power supplies. Both not original. One looks like a nice quality one with the correct polarity (positive on the outside in this case) and the other one is a shitty cheap Chinese thing with incorrect polarity. Hmmm. I tested the nice one and sure enough I measured 9v (as indicated on the power supply). The other one should also be 9v but I measured 17v.. (without load that is). I decided not even to use the shitty one but the previous owner probably tried it. It has incorrect polarity and therefore the A-33 will never work with it. You might even break it by connecting it. Rolands usually have a diode installed to protect the instrument from damage by connecting a power supply with incorrect polarity so I hope it’s fine.
Tested the first A-33 and that one works just fine. A few keys aren’t velocity sensitive but apart from that all is well 🙂
The second one: dead as a door nail 😦 nothing happens when I connect the good power supply and flick the switch. So I’m going to open that one up first to see if I can fix it.
Will update soon!
Update september 3rd 3016:
I’ve been busy with a lot of thing lately so I only have a small update regarding the A-33’s:
I’ve got one working again and the other one is still dead. I’ve swapped one of the keybed pcb’s of the bad one to the good one because some keys didn’t work and I couldn’t find the broken trace fast enough. 🙂 Now one works fine.
The other one gets power but still doesn’t do anything. I’ve compared voltages and both A-33 put out the same voltages after the power pcb to the correct pins after the powerboard so that’s fine. I’ll continue my investigation soon.