Hi there, just picked up a VK1000, I have an electronics background but i’m stumped and looking for help.
The keyboard powers up, lights and buttons work, sounds are all garbled and appear to be same frequency up and down the keys (not all work) then it just stiffs up no buttons / keys work. I have to power cycle and then if i go into test mode, i can run some tests for a short time (10 seconds or so) and then it hangs up again. It seems the levels and bend controls all work (in test mode). Also, in some cases, the display overwrites itself when you change from test to test (ie it doesn’t clear properly so becomes garbled). The main PCB looks clean and i can’t see any puffed up / leaking capacitors, or any damage. I pulled out the EPROM cleaned it all and re-inserted it - no difference, all other chips are soldered down.
I wonder if there is an issue with the CPU, i.e. does it access a memory location where the RAM chip is not responding, or is there some crazy interrupt problem ?? - anyway, any thoughts or pointers gratefully received please !