AA, I took your picture and added the places where the caps need attention. I know I put them on the schematic for you but this should help others, too. With a bit of time most anyone should be able to see what cap goes where on the drawings.
The ones in blue are the areas where you'll need to focus. The ones in red, leave alone until you're happy with the performance and the operating voltages are in spec.
I _did not_ mark the high voltage filter caps that oboviously need swapping out. I _did_ mark the low voltage filter cap in the lower corner as it, too, is leaking.
Lastly, I normally install a CL-90 thermistor inline with the AC line. The most convenient point for that is to remove the jumper wire from the back end of the fuse holder over to the AC socket. Use some tubing on the exposed legs for safety when it is installed. I generally install it so that the heat rising from it will vent straight into the holes above it. This would help the inrush into new filter caps after swapping out the 4 selenium recitifiers you see circled.
Beware that most all of the terminal strips will be quite brittle and the phenolic will break easily with movement as you try to remove a component's leads from it. Best to cut the leads from the components then solder sucker out the solder and then cut the left over leads from the eyelets to minimize stressing of the strip. How do I know this?
As for where to put the premium caps, I'd suggest the preamp section working backward up the audio chain:
- C106/107: Last stage of the preamps. Those 1uf electrolytics gotta go. Space will be a bit tough. Plan on replacing the resistors around them to fit a decent polypro in there. They'll be big so space will be an issue. I'd use an Illinois Cap or, splurge, an Auricap.
- C96/97: Input into the tone control network from the Tape Monitor switch. I'd use some Illinois Caps or Auricaps here. Someday, I'd like to make replacements for the PECs - those encapsulated networks you see. I started on them but never got done with the project.
- C91/92, 93-96: 6D10 Tube Buffer. The paralleled output caps can be replaced with up to a 3.3uf on the output side of the 6D10. Same brands as above or anything that Terry Dewick blesses should work here. I've used no-name polypro caps here with excellent results. Ditto on the input side, C91/92.
- C85/89, 81/82, 86/90: Phono Circuit. C86/90 are those black banded caps to the input switch. The others are the interstage coupling caps. I used Solens myself but they're big and space becomes tight quickly. If I were to do it over, I'd be using Illinois Caps or Auricaps.
- FM tuner outputs: I used no-name polypros here but would suggest the Illinois Cap again.
BTW, the reason I've gotten to like Illinois Caps these days is the wider range of operating voltages you can get from them. The big Solens, Auricaps, etc, are a pain to work with when about all you can get are 400v or higher caps. These can get huge depending on the value. With such tight working quarters in the Mac, Scott, and Fisher stuff, they just don't work as well for neatness and layout.
Overall, though, the improvement in bass slam and wider/more stable imaging will be your results no matter what. Just make sure the power supply voltages and the operating voltages around the tubes are in spec. You'll also get far more accurate results from tube rolling with the changes you are contemplating.
Hope that helps.
Cheers,
David
