Missing component in Mark III?

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Bullen

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Hi guys! So, I was looking over the caps my red stripe Mark III today, since it has developed a hum lately and I thought I would have a look. The caps are probably original, the bigger blue ones are all Mesa labelled. One of them had a small hole in it, so the amp needs new caps.

But anyway, I looked over the curcuit board to see if I could see anything else weird or wrong. And I noticed in the top right corner of the main board (with the front facing towards me) a missing piece. It says R117 on the board (right next to R102 which is not used it seems, no eyelet holes for it). It looks like something was there earlier. I had the amp in for servicing about 10 years ago for a power related problem, maybe it got removed then. I'm not the original owner so I don't know what has been done to before I bought it.

This amp is a 87 red stripe, Simul Class, eq and reverb model. It has the selectable volt switch on the back.

So does anyone know what R117 does? Do I need it? What value should it have on a red stripe?
I thought I would check with you guys before I take it to a tech. Thanks!
 
R117 is the spot for another bias resistor if needed.
That is where a tech would install a resistor or potentiometer to adjust the bias for another set of power tubes.
Do a search for R117 on this site and you can find plenty of reading on it.
 
Thanks! Yeah, I did a search after I posted. So now I'm up to speed on the R117.
 

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