This tech has been on hold since last year as a project for this year. As if I needed more work.
An interesting tech, all built into a frame case with plug in circuit boards. With each new tech a tester has to be built otherwise it's almost impossible to check everything. This time I'm building a hybrid one to test Black Box as well so the old adage of killing two birds with one tester is apt.
Anyway down to the nitty gritty.
The main issue with these boards is the CPU card as corrosion is rife from the onboard battery. Luckily it doesn't spread to the rest, certainly not in the few examples I've seen so far.
So starting with the board on the bench it looked like this...
First thing is to strip off 'all' the old components. Sounds easy but it took nearly two days to get all the bits out as most of the solder had gone grey and crumbly. All the connector pins were green so they had to come off too.
Fingers crossed the CPU is OK but you can see it has a sort of 'rainbow' effect on the top and in my experience that is usually caused by it overheating!
Unfortunately with jobs like this some solder joints just won't let go of their component and what's left of the via and pad comes off with it. I wouldn't even attempt working on a board like this without my rivet kit!
With new rivets in, a good clean up and application of solder mask it was time to put the new bits in. I had to add a small piece of copper to the battery track as it had eaten through on the top side.
I made a deliberate mistake above. Don't worry I corrected it later.
Nearly all done. Sort out a new set of chips barring the RAM and CPU. I'll keep my fingers crossed they work otherwise it's going to get expensive.
The only bits I'm short of is the two mica caps that tune the crystal and the 7442 chip which I didn't have in stock. Hopefully they should arrive in a couple of days.
Knowing what I know now I don't think I'll be taking on any more corroded CPU cards as this one has taken the best part of three days! Oh, I forgot I've got another one to do.