I have recently repaired three Amiga 500/500+ computers and they all have damaged keyboard membranes. One membarne was salvaged using conductive silver paint, but two could not be repaired. I could of course order a new membrane, but they cost around 35 EUR. I understand where this price comes from, but for two membranes I can buy a fully functioning Amiga 500. So yeah, I think they are expensive. PCB membranes are also available, but the cost is about the same. So there is probably no way to repair Amiga keyboards cheaply … Or maybe there is?
Sometimes repairing a retro computer is as simple as replacing a leaking capacitor or a broken chip. It only takes a few minutes. But there are also tough cases where you can spend several evenings digging around the board, diagnosing, testing, and all to no avail. Usually I go back to such cases from time to time and sometimes I end up finding the culprit and fixing the damn thing. But some cases are so hopeless that it is not worth wasting time on them. This post will be about such a case… and the Commodore 64 necromancy 
Most of retro computers were manufactured in 80s and 90s. After all these years plastic parts often turns yellow, or even brown. Thats mostly caused by exposing it to UV light like keeping it in sunlit place etc. But even without UV light plastic will degrade over years. Except for changing color it can also become brittle. That said one may wonder… How is it possible that you can still buy old computer and it looks just like new? Well, basically it is possible because someone probably refurbished the computer or it was kept in environment which allowed it to be preserved in excellent condition.
So how old computer is refurbished? There are many ways. For example I start by carefuly taking computer apart to separate electronic, plastic and metal parts. Each of these needs different treatment. Electronics may be simply dusted off with soft brush. You can also use special fluids for cleaning electronic parts and PCBs. Most common one is isopropylic alcohol. But thats not the topic we will discuss. Also metal parts restoraion will not be covered in this text. Lets just say you may need to clean metal elements like board shielding or RF modulator boxes from rust and protect them against it in the future. Today we will focus on deyellowing plastics.
After year long break I finally found some time for posting some short reviews of 35mm lenses. These days I’m more into electronics than photography and I’m afraid it won’t change anytime soon. However I’ll try to finish what I started and test all remaining lenses that I have. The 35mm tests are last ones performed before changing testing environment a bit, hopefully to provide better results. In fact I tested all my 35mm lenses year ago but never managed to post results. I’d reshot these tests in new environment but I already sold some of lenses. Also please forgive me nice piece of lint visible at higher F numbers 
I’ve noticed it after conducting the tests and was too lazy to reshot everything.
We will start our 35mm journey with Minolta MD Rokkor 35mm F1.8