Most of the board is depotted now, finally. I found the fricative (white noise) generator on here. It is composed of a quad XOR gate and some shift registers.
Depotting is messy business for sure. I think most of the black on my hand is from the damn knife handle though- that aluminum seems to be rubbing off onto my fingers or something.
Finally! Down to the very end. The trim pot has been removed (I don't know what it is for yet) at this point.
These are all the old parts that were removed. Most of them are damaged, but all the chips should be OK. So far, I have not had a bad chip.. yet. With these 18 chips, I will have removed exactly 59. I will re-use some of the caps, and the chips, but nothing else. It will have all new resistors and mostly new caps.
Top of the bare board after de-potting. None of the routes have been fixed yet.
Bottom of the board.
The mess left over! That's all the epoxy and bits o' parts left over from de-potting today.
Here's the parts that will be going back on the board.
And the chips. Like before, I tested each chip to make sure they were all in good shape and working. I seem to have *bent* one of the MC1437P's during removal or something, since the damn thing has a definite cambre to it that I don't think comes from the factory... I tested it, however, and it works just fine still! These chips sure are tough. I have "processed" a total of 59 chips now, and all have worked after the de-potting ordeal. I have not had to replace a chip... yet.
And now all the passives and diodes and the single transistor are on the board.
Finally, all chips are on as well.
Schematic of this board. (note: clicky for larger)