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

[jebem]

(01-20-2016 08:06 PM)Adalin Wrote:  So I finally got the eeproms, and started the procedure immediately

Well done. Thanks for sharing your findings!
By the way, where did you get those EEPROMs?
I might order a few, just in case, if the price is right.

(01-20-2016 08:06 PM)Adalin Wrote:  I accidentally sucked off two solder pads with my solder sucker, that was not a wise move but I didn't want to use a de-solder wire because I didn't want to heat up the pads too long, it really is a crappy pcb, extremely fragile.

Tell me about it... no matter how careful one is, at least one pad will be striped no matter what.
These PCB's reminds me of my good old teenager days when we use to make our own PCB's using chemical etching, I think we used mostly iron perchloride and a home sink.
Fiberglass material was out of question due to the high cost, so we ended up using phenol resin (I think) like this one used in the MK's.

(01-20-2016 08:06 PM)Adalin Wrote:  I bought another mk-61 last week also, and it had a strange fault when I started it, the vfd would show every number and point lit and scramble all the numbers (...)

I put the capacitor in my esr meter and it showed 20 Ohm internal resistance and vloss of 30%. compared to the new one I put in that measured 0,13 Ohm.

So if you have problems with your mk-XX calculator, replace the capacitors first.

Yes, that's my findings too (reported in this thread somewhere in one of these posts).

Just for clarification of those less enlightened in electronics:
A DC resistance of 0.13 Ohm means the capacitor is bad (in short-circuit) and needs to be replaced; however your reported reading relates to AC impedance and its value should be as low as possible.
I believe that not everyone here has access to a ESR meter, so most of us end up using a ohmeter that will give you just DC readings.