This is the first SX-650 I have worked on and also the first one I have worked on that has the integrated output transistors. This has the SanKen SP-40W packs that most in the antique audio forums call “unobtainium” as it is nearly impossible to find replacements. These units seem to be fine as I continue to test this receiver after each major step of restoration. This receiver makes it very challenging to replace the electrolytic capacitors because these 2 amplifier boards (GWH-101 and GWR-101) are mounted together in a bracket with the big heat sink for the SP-40Ws. After removing the brackets and heat sink I was barely able to get enough room to get my Hakko desolder gun in to remove the old capacitors. You can see the new replacement Nichicon gold capactors and the old blue Nichicon caps. Another surprise was that the remaining blue caps you see do not match what is in the schematic although they do look to be completely original to the unit. C27 and C28 are 220uF@63v and not 50v as in the schematic and C28 is 4.7uF@50v and not 35v as in schematic. Unfortunately, had to place another order with Digikey for these items and it delays the application of new heat sink paste and reassembly.
One tip – When doing desolder or soldering in tight spots or around wiring, I like to cover the wires with some tin foil. Its too easy to accidentally burn some wiring with the hot iron or drop some solder somewhere it should not be. I am really looking forward to getting this back together.