HBrown
Active Member
I recently pulled this RCA RS-199C amp out of an old console. I've hunted high and low for a 'C' schematic- its supposedly in Sams 683-13 but I cannot seem to find a file that will open on my android device. If someone has a pdf, I sure would appreciate it. I did find a schematic for the RS-199B. I saw where another poster said there were not large differences in the 'B' & 'C' variant, so I am referencing the 'B' schematic so far.
I have repurposed several console amps in the past. Mostly amps that worked as-is with just power switches, and RCA inputs being added without too much effort being put into them. That being said, I am confident working with the voltages, I am just not really deep into the tube amp engineering side of things. I have a Dynaco ST-70, an Allied tube receiver, and multiple console amps I have been into over the years. I mainly repair and refurb SS units, but I like a nice tube amp as well. I know the electrical safety issues involved here, and will observe all caution.
So, I looked at the amp, and schematic and determined that jumpering pins 2 & 3 on the 9 pin socket should power the amp up. I hooked a pair of bench speakers up to the outputs, and a cd player up to the signal inputs. No sound, no hum, no nothing. The tube heaters are lit up, but it seems there is no B+, or something is open somewhere. I did try it in the whole console before pulling the amp- The console lit up, and controls seem in good shape, but no sound at all then either. I figured I would try because the console is really in very decent condition. If I can get the amp going, I may return it to the console.
I'm not very 'up' on the whole understanding of the voltage multiplier circuit used in this amp. The main transformer wiring colors are miserable- can't be certain which wires are which.
Firstly, can someone help me determine if my main transformer is good? I'm not finding B+ anywhere. I need to isolate the transformer and see if it is doing anything. What voltage should I be getting from the transformer itself before the voltage multiplier circuit? If it is not good, then I just have more 'old tube amp parts' for my parts warehouse. If it is good, then I wouldn't be adverse to putting a few bucks into some caps & parts. I realize those tubes don't look so great. I do have some working, but not great 6BQ5's I can try in it, but I'm just trying to get B+ at this point.
In my underside pic, what is that wire to the left of the red wire in the top right corner connected to the terminal strip lug? it goes to nowhere- there is nothing else connected to that lug. The 'B' schematic I'm referencing has an 'F401' in between the red lead of the HV transformer output and the rectifiers- is that a fuse? I see nothing like that anywhere?
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