OH NO!!!! Unattached wire found during recap!!

[andylevine]

Busy recapping a MRA3-L6 for my M100B.... removed one of the larger caps (C16 or C17 I think) and underneath I found a loose black wire just sitting there.  Not sure if I had cut it accidentally or if this was done intentionally by one of the previous owner/maintainers.  My schematics are PDFs of copies of copies so its VERY difficult to trace where this may need to go. I have a decent printed manual for the M100B, but it has MRA1 schematics.  The one soldered end is on Pin1 of the 6SK7.  I see another wire coming off that pin going to the mute plug.  I would not be surprised if someone cut this purposefully trying to disable squelch as the B has no hardware to disable it. I also see a couple of resistors on that pin.  I also just noticed that Pin 1 is jumpered to Pin 7 so that might be the pin that needs to be traced.

 Can someone with a GOOD readable schematic tell me where they think this wire may go??  Wouldn't surprise me if it goes to the solder terminal strip between the tubes, just not sure where.  

I plan to try and add the squelch contacts to my B mech at some point if that matters.

Thank you
Andy

[Ron Rich]

Hi Andy,
I would not hesitate a guess--only suggestion I have is to purchase a "LEGITIMATE" copy of the service manual--and BTW--didj read "HI Newbies" in the FAQ section above--??

[andylevine]

Ron, I DID purchase the ‘legit’ manual for my box from Victory... it’s just my box came with the wrong amp. And to be totally honest, even the schematics for the MRA1 in the printed manual are too small and too fuzzy to really be much good. What I really want is LARGE FORMAT well printed schematics that I haven’t seen available. I have found some better ones online but nothing good enough yet.

Oh.... also purchased your mech guide, the Restoring the Mechanism video, The Dr Know It All book from Harold Hagen and a few others as well. Yes, I’m well researched.... anything I’m missing? Is there a place just to buy decent schematics, because obviously I’ll put out coin.

Thanks

[robnyc]

Andy, pin 1 is N.C. so it must be used as a tie point here.

www.radiomuseum.org/tubes/tube_6sk7.html

Pins 2 & 7 are heater.

Note that the AGC section did receive some mods regarding resistor values in subsequent designs, the basic architecture remains the same thru V-Vl -so you can look at some of the online schematics for those to get an idea of where your wayward wire goes.

Here is a good clear one: www.verntisdale.com/schem/hfma1-l6.jpg

RobNYC