Help with amp pcb

[atriptothemoon]

hi all, find myself at home with no access to mate based expertise! For soldering and general practise I decided to try and track down the source of hum on an old whafedale-pro power amp (an EVP 12PM).  Before recapping the smoothing caps I've had a look at the other components. The pink resistor is different to all the rest. See pix. It looks to me like it is a 0.47 ohm 5% tolerance resistor - can someone reassure me I have this right please? so I can test.
While the other resistors are all shiny the pink one is matt and looks "dusty" - is this normal and likely just a consueqence of the type of resistor it is (unfortunatley I have no specs or circuit diagram for the EVP-12pm) or a tell tale sign of some sort of damage?
Any help gratefully recieved
thanks all

[Kim Christensen]

Looks like a 4.7 ohm 5% resistor to me. (Yellow Violet Gold Gold) But it might be in parallel with the inductor next to it, and if it is, it will measure zero ohms in circuit.
Yea, it's normal for some ceramic resistors to have a rough texture like that.

[atriptothemoon]

thanks Kim

[srb1954]

hi all, find myself at home with no access to mate based expertise! For soldering and general practise I decided to try and track down the source of hum on an old whafedale-pro power amp (an EVP 12PM).  Before recapping the smoothing caps I've had a look at the other components. The pink resistor is different to all the rest. See pix. It looks to me like it is a 0.47 ohm 5% tolerance resistor - can someone reassure me I have this right please? so I can test.
While the other resistors are all shiny the pink one is matt and looks "dusty" - is this normal and likely just a consueqence of the type of resistor it is (unfortunatley I have no specs or circuit diagram for the EVP-12pm) or a tell tale sign of some sort of damage?

The "dusty" surface is normal for that type of resistor. This resistor is probably specified for a higher power rating than the other resistors beside it and will consequently run at a higher surface temperature. The "dusty" coating withstands those higher temperatures better and doesn't burn or char like the lacquer coating on the other resistors.

[atriptothemoon]

thanks srb thats really useful infor - and what Kim said about it running in parallel with an inductor - all helps with my learning curve!

[Terry Bites]

4.7R 2W 5% is shown in the service manual schematic.
BTW Along with the indcutor and C23 it forms a Zobel network.

[atriptothemoon]

thanks Terry - could you link me to the schematic please?  so I can have a go at trying to at least partially understand it, as well learning what a zobel network is :-) 
I am beginning to get an idea about amplifiers but am very much at the beginning -  cheers 

[atriptothemoon]

hiya - any chance of a schematic would be really helpful - cant ind one online :-)

[Xena E]

Heres a link
https://www.google.com/url?sa=t&source=web&rct=j&url=https://elektrotanya.com/wharfedale_pro_evp-x12pm_sm.pdf/download.html&ved=2ahUKEwif58KK8rX9AhVihP0HHYyWC1AQFnoECA0QAQ&usg=AOvVaw3qA0t4m7GQHHopLMrgYKYi

Regards,
X