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

[linuxslate.com]

OK, bumping a really old thread here, but I just learned about these, and purchased one through "a certain popular auction site".

It seems to generally work, but it does have 2 issues that I am contemplating on attempting to repair:

1. The keyboard foam has gone flat. The keys all work fine, but at rest, all are crooked, and the keyboard has no "feel". I purchased some thin insulation that is meant for insulation around a window air conditioner installation. I will cut to size, poke holes, and try it. If anyone has a better suggestion of what to use, I am certainly willing to hear it.

2. There is something wrong with the EEPROM. If I save a program, and then recall it, it is generally correct, but functions that are represented by larger code values change. For Exampe: 4A X->N(a) may become 5B when the program is re-read from EEPROM. (not sure it is exactly those values. I'm too lazy to determine exacty what bit(s) are flipping)

I figure the 3 most likely causes are: -- Improper Write Voltage from the power supply -- Bad solder or broken path(s) near the EEPROM -- Bad EEPROM chip.

I'm pretty sure the bit errors are always the same, so I guess this reduces the likelyhood that it is a Write Voltage problem.

It has the seal on the screw, but to fix the above, I guess I will have to remove the seal.

I expirienced at replacing old caps, since I also work on vintage tube audio equipment -- which pretty much means -- I replace bad caps.

The Transformer in the AC adapter does seem to have another primary tap. Does anyone know if this can be used to make it work with 110V - 120V?

If not, I plan to cut the wire off of the AC adapter, and attach a USB connector to the adapter end of the wire, thus making a USB power cable.

Lastly, I have written a simple proggie to roll a dice using a super simple implementation of a "Middle Squares" psuedo random number generator, which creates seeds for the internal psuedo random number generator.

Willing to share here if there is any interest.