Marantz SR 18 powers up - no sound , no secondary relay click

Before you begin your journey to explore possibilities of repair, open your top cover and bottom cover. With clean paint brush sweep off debris and DeOxit the unit and let it rest for half-day. Turn back on and see if problem is solved(you may get lucky!)

If not...

 You can short high-current output of relay(find specifications of this or similar relay from major electronics catalogs such as mouser, newark or digikey) and see if your poweramp section turns on. If not, it's not discrete unit(only output stages are) and has bunch of logic IC boards that are far less durable than discrete devices. The way to test these boards or schematics or even simple block diagram are under the heavy secrecy of the manufacturer unobtainable by neither independent techies or casual buyers.

In my opinion such unit is never worth repairing besides the fact that it's sold for in working condition near $300.

If you go to HiFiengine.com, you will find most of great discrete vintage units schematics and service manuals. These units ARE serviceable and can be brought to PERFECT operating condition.

You can DeOxit whole thing, but mainly all switches, potentiometers external and internal ones. External ones for users and internal ones for adjustments by tech that might have paint drop on them for proper position.

To short relay, you will need to unmount it first and than short output terminals. Stay ALERT and touch transistor chassis to make sure you don’t spot ones running too hoter the the others...

Logically the blown output transistors can cause the relay not to engage, so as a matter of fact need to remove and test them. There's plenty of material how they're tested with simple diode tester or DMM.

I don’t think there’s service manual for this unit. They’re obsolete since late 80’s. A detailed service manual had been replaced with phrase "Opened only by qualified technician" -- it’s shorter and makes all users bring units to repair facility and pay $$$ for repair. Contrary in 70s units there are detailed circuit diagrams, drawings of boards and ’foil sides’ with all possible voltages and currents, knowing that owner can choose to troubleshoot unit on one’s own or even LEARN HOW. It makes me said knowing that word LEARN had been permanently replaced by word TRAIN.