2015's calculator anniversary - the SR-52

[jebem]

I realize now that I have hijacked Gene's thread.
Should I create a new one?

Small update on my SR-52 repair:
- After PCA cleaning the issue remains the same, despite some variations, but in the end I allways get a crash (the two minus indicators are lit and requires a power cycle to recover).
- I'm using a 4VDC external power source connected to the battery terminals:+Vss (common) and -Vbat.
The Internal DC-DC converter seems to be good (Vdd = 10.5V, Vgg = 16.3V).
Although I still have to check the power lines noise.

I started my quest to get an SR-52 Maintenace Guide. I will get one, no matter what.
I know that we can use the TI-59 and the SR-50 service guides publicly available as a reference, but I like to have the correct documentation whenever possible.

After a few mails sent to Gene Wright, Joerg Woerner and Viktor T. Toth, I have a few more ideas.
Thank you all for your fast answers with tips and experience sharing on these machines.

Basically, the cleaning must be deeper than what I have done so far.
Most probably I will take extreme measures by removing all the IC's to clean under them.
At this point, I have nothing to lose. If an IC is defective, I would have to replace it anyway.
Problem is that I can't find any spares for these machines anywhere.