Elektronika MK-52: The MK-61 big brother?

[clarke2001]

Thx for reply, I tested the DC unit (converter) always plugged in.

Let's number the machines: 1. the working, good one. 2. the defective.

As mentioned above, for a few seconds I plugged the 1. DC-unit into 2. then turned on.The wrong operation (K-prefix issue) didn't change, so I quickly turned it off, to prevent possible DC-unit damage, and plugged it back into the 1. The 1. works good.

Without scope figures (provided on the original technical documentation), the only possibility is the comparison of 1. and 2. using oscilloscope, measuring voltages etc. But I'm afraid, something gone wrong in 2.

Are there original schematics of MK-52 available ? I have one from net (quite hard to read), but without scope figures.