47K is the standard input impedance for a phono section, MM or LOMC.
If this were mine I'd using a DVM and measure the resistance between the connections of the RCA jack and see what's there. I'd also use the DVM to see what the RCA plug thingys are as well.
You can't just use one value for MM cartridges; its variable depending on the cartridge and the tonearm interconnect cable! Take a look here:http://www.hagtech.com/loading.html
100 ohms isn't a standard either- when a load like that is specified, it suggests that the phono section is vulnerable to the RFI generated by the cartridge messes with the input of the phono section. See that link above.