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.

Thank you for your quick response.
Two questions:

Should I bath the electronics in DeOxit or just the relays?

Could you please help me understand how to short the high-current output of the relay - - I am pretty technically competent but have never seen the inside of this SR18 (just got is Sat. and found out that there was no sound). Any help you could give me to try and diagnose the relay issue - with slightly more specifics to location of relays and the technique to short.
I have not been able to find the manual of the SR 18 on line only the SR 18EX which at this point I do not know the difference in electronics.
Again thank you for your help

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.

Thanks again for your quick response.
I do have the service manual with all the layout diagrams.

As you suggest I will try the DeOxit tonight and let it sit till morning.

I had a similar problem with an older CARVER receiver that had blown relays (known problem with these receivers).  
I will let you know the results tomorrow.
Again, thank you for your help