Thanks, Dave. Hopefully between us we can save a few more of these incredible sets.
One exception would be that you don't have to spring for a higher-heat than normal soldering iron for those heat sinks. It's really not necessary.
I just checked again, on the board I am presently working on, and the heat sinks only connect on one end, at all points. They do not provide a connecting path between anything and anything else in there.
As such, they cannot cause erratic or intermittent ops if their soldering breaks down, as it usually has done by the time I have received a board for resoldering.
The most that conn does is clamp the sink to ground on one end. This can provide potential anti-noise properties, but that's only theoretical, and I really don't believe it carries any weight, electrically. I have never resoldered them on the boards being sent to me, and have observed no such noise to be worried about, in the ones I have then observed in operation afterwards. Heat sinks just sit there in the air, not connected to the devices they sap the heat away from - directly, inductively or any other way. They don't really need grounding on this kind of board, which is a relatively low voltage board and neither needs nor uses shielding around any of the components because it does not deal with RF frequencies. What frequencies it does deal with are very effectively eliminated via the coils and caps presently in the sys as it is.
Pioneer also soldered in a coil on one side of the board where if you study it, you find that it has a jumper right across from it within an inch of it, which directly shorts it, disabling it completely. Meaning it cannot attenuate any high frequencies, which is what coils do, because it's shorted out!
This coil is NOT on the boards used for the x20 series. Nor are several bigger coils in the incoming 120v. line. In the following year, Pioneer obviously found they were not needed, and eliminated them from the design of that board from then on.
So I would not worry about the heat sinks. I DO resolder the one grounding screw that solders the screw to the board, tightening it also as it gets soldered. But that only connects to a cap, so it's not really critical anyway either, as a source of the intermittent problems. On other boards I have seen that screw take down the entire ops of the set, but I didn't analyze why, I just resoldered it, the set worked again and I was outa there, because it was the third visit, where on each visit I had APPARENTLY fixed the set! So I do it as a matter of course now.
On all else that Dave said, listen up! He's trying to help you guys out there, just like I am!
Thanks again, Dave, glad you chimed in -