The first choice to make is to buy all the caps yourself from Digikey or get a prepackaged kit. The kits are more expensive but if you dont place to make a hobby out of this, then they are an easy way to go. You can get a complete cap kit for the 2226B for about 60 dollars with the nice Nichicon Gold audio caps and another 20 bucks for the two filtering caps of the same make. Now, you can buy the two filtering caps for 6 bucks each from digikey (plus or mins a few depending on brand)...but it's convinent to have a small package show up ready to go
That was how I started before I decided I liked this as a hobby and stocked up on parts. What you dont get with the kit are any repalcements of electrolyitcs with WIMA films for example. Another choice is how far down the rabbit hole do you want to go with the caps. Some just replace with like, some like to upgrade a bit ( slightly more capacitance on the filters for example) and some like to buy high end coupling caps. I would suggest doing the like for like with a couple of changes.. The two primary filter caps are 6800uf at 63 volts.. I went with 8200uf at 80 volts. I did buy some diodes ( 1N4444 and 1N4448) to replace a few but in the end, the original tested good and I couldnt find any real reason to pull them. I also bought a TIP31B for Q750 on the P700 board. That is a 2SD330 and TIP31B is the more rugged replacement. That one you need to decide how much work you want to do. It's mounted to the main heat sink and it's a bit of work to get out if you dont plan on cleaning up or replacing the main amplifer transistors. Most dont replace it unless it's bad or showing signs of instablity.
The tone board is a PIA to do. you can get to about half the caps without removing it but ultimately you need to unscrew the nuts on the pots, take out the power siwtch, remove the speaker switch rails ( the extensions), remove the chassis screws on the power switch side and loosen them on the other and then gentle pry and twist the board out from behind the chassis. you can can just enough movement to get 90 degrees of twist with caution. That means you can get to all the caps. There are some non-polarized electrolyitcs in middle of the board.. replace those with some WIMA films. Dont worry about the two big brown .22uf 50 volt caps under the volume. They are pretty durable as I found out :/ My cheap replacements didnt work out well at all. Speaking of which, dont get cheap imported shit.. get brand name or buy from a known supplier like Mouser, Digikey etc. I went cheap for a few and regreted it.
Dont just replace the power switch because everyone does it. The OEM is really good quality and rebuildable if the contacts are not fried. It's worth a look before you hack it out. The trick is to use a very thin blade to GENTLY pry the wings up and over the studs on the sides. Get a relay burnishing tool and some deOxit and clean the contacts. Then get some Deoxit L260DNp Mechanical and Electrical Grease and put a dab into each of the contacts. The grease is non conducting and has DeOxit in it to keep things clean plus lubed. Push the ears slightly together and then re-assemble making sure the spring doesnt get pinched in the gap. Works fine.. lasts long time
You will need a stock of DeOxit cleaner spray.. and I use DeOxit fader lube afterwards for the pots. These are 40 years old and even clean, they are worn so a bit of lube doesnt hurt.
Do NOT DeOxit the tuning cap on the tuner board. it's an air gap unit and the spray screws up the capacitence. I use a electrical contact cleaner that dries off completely after some canned air to blow out the dust bunnies. I put a drop of electrically safe lube on the bearings/gears but it's a very small amount. I would suggest that no-lube is an option since very few of us actively look for radio stations every day like we use to. And the oil just attracts dust. Something to think about.
I use Kesters active rosin solder, their no clean flux in a squeeze bottle, solder braid/wick ( I hate hand solder sucking tools) and weller iron with a wedge tip that can really put out the heat for fast melting/removal but it does require a deft hand or you will lift copper from the board. I have yet to lift any pads but then I've been using this iron for years. If you new to soldering/desoldering.. buy some junk radios or whatever and practice your de-soldering skills first. It's worth the time and a few bucks in materials before you attack your Marantz
A small LED flastlight is invaluable for lighting the dark corners while working
With light corrosion on the RCA jacks, you can buff it off with some mothers mag polish by hand or with a dremel tool if it needs more persusion. Nasty cases can take some 0000 steel wool and care then polish
Something to remember is there are ten ways to do most of this. And all ten work fine for the most part. What see here is what worked for me and that might change as I go along doing more restorations.
Brands of caps I use.. Nichicon, Rubycon, Panasonic, Wima, "orange drop" .. these are driven by cost and by availablity. People swear by Nichicons but in the filter caps I dont see/hear a difference between them and the Rubycons for example. The Rubycons are cheaper, rated pretty much the same and built just as well from what I can see and test.
I have pictures of most of this including rebuilding the power switch. I just havent posted them yet. And I'm sure I will remember more or someone will add more to this.
Above all, have fun! it's not hard work but it can be a bit tedious at times.