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Rca rs199b

jgsulliv

jgsulliv

AK Subscriber
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I just bought an RCA RS 199B as my first restoration project. <newbie> I'm looking for guidance on how to proceed. Redboy kindly provided a stock RCA schematic. My unguided approach would be to recap as it's wired today.
3 questions,,, am I missing an opportunity for a better sounding amp by not modifying the stock circuit? Is there a place I can find recommendations regarding the wiring of the power switch, indicator, fuse, etc. And what are some favored sources for switch, fuse, power indicator, RCA and binding post and the like?
Thanks for any help you can give folks!
Jim
 
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If you can post the schematic it would go a long way for those to help out with.
 
Hi Kegger and other interested AKr's
Heres the RS199B schematic and parts info.
Thanks for any restoration/ improvement info you can offer!
 

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Took another look at your schematic, and some first thoughts...

  • The power supply is pretty robust for a console amp, with lots of capacitance. You'll want to replace all those electrolytics with new ones, of course.
  • Replace the X4 and X5 rectifier diodes with new
  • Install a proper fuse! Wow, they spec "1" length of #26 wire... :yikes:
  • Looks pretty straightforward overall. Others will have input on the schematic, but I bet this will be easy...
 
You can just do the simple recap and redo and have it work fine.

--- OR

If it were me I'd go the route of the schems I'm posting on the unit.
(an replace the 100ohm resistor in the supply with 100ohm choke)

I'm posting the original modded just showing one channel and supply.
(plus cleaner version of "same" audio circuit, voltages just reference)

Can roll in 6DJ8, 6BK7/6BQ7/6BK7 for the 6AQ8 in this version as well.
 

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Thanks Redboy and Kegger for your comments/ input.
I picked this version of the schematic off the net today.

Kegger,
I found a 100ohm choke on the auction site for $8. I see two resistors in the circuit, the 100ohm 7W, and a 390ohm 7W. Does that mean I need another choke?
Jim
 
RS 199B - Beitmans Schematic

Now with attachment!
 

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I'm not sure what your referring to?
I see no other 100ohm 7W, and a 390ohm 7W resistors?

And you say you picked "this" version off the net, what version?

---------

If your talking about what I posted the 100ohm choke would Replace
the 100ohm resistor I point to in your original power supply schematic.
 
OK now I see the schematic in the next post. :)

---

Myself I wouldn't build that version, (not enough gain for me with fbk, and I prefer different fbk)
And you don't need the 390ohm resistor there, that would of feed something else in the console.


You can certainly build that version, it's just not what I would do. (I just prefer a different route)
(but by all means you don't have to do what I would do) ;)

Also that 6FQ7 and 6CG7 would drop in the circuit I posted and have low gain, just like the other.
 
Hey Kegger,
I have no preconception as to which way to go. In fact I have no idea. This is my first step into messing inside tube audio beyond replacing caps in the Heathkit AA-32 I bought from you on BT last year (BTW, it sounds great).
What I'm looking to do is learn by doing and seeking some slow step guidance as to what to tackle first to result in a :thmbsp: SE amp (I hoped this RCA iron is a good platform for that).

So far I've ordered the larger caps, 100uF 350v x 2 and .25 600V x2, RCA jacks and binding posts, as well as the 100ohm choke you recommended.
I gotta figure out the power switch and fuse wiring, input and output install and choke placement.
I can replace caps okay,, the rest is a leap for me.
This thing came with and additional tranny half attached at the molex, I assume it's part of the preamp and not needed.
Thats my story so far. I'm daunted and excited at the same time, I like the idea that I may figure this stuff out (with help) and become less of newbie.
Thanks,
Jim
 
Yep the only way to learn is by doing, so jump in there and start figuring, we'll help.
 
Hi, I too, like the OP have come across a console with the RCA RS-199B amp section. Some searching led me to this thread and I want to build the circuit outlined by Kegger in post #5. Being a novice at electronics and this being my first tube project, I wanted to verify a few things before I order parts and start assembly. I've attached a copy of his schematic with the power supply drawn and some pin numbers added. Now for my questions.

1. Are the pins I labeled all correct?

2. What would be an appropriate power rating for the resistors in the audio section?

3. Would the Hammond 159Q work for the choke he recommended in the power supply?
 

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1.yes

2. I would use 1W for the 39K plate loads, the 100K feedback and the screen stopper. 1/2 W for the others. Power tube Rk and the 1800 dropping resistor 2 or 3 watts.

3. Yes. It has the desired DC resistance and can handle the current for the whole circuit.

Let us know how it works out!
 
Awesome. Thanks for the quick reply. I will be putting together a parts order tonight. And I'll start new thread when I, a) run into some problems and need more help or b) have something to show off :banana:
 
One more question, how flexible are the capacitor values in the power supply? Partsconnexion has some 60uf ASC film caps at electrolytic prices
 
Thanks. It’s dead quiet on my speakers, about 90dB sensitivity so not super high, and has a great midrange.
 
With a solid state rectifier you have a lot of flexibility. Keep in mind that with a voltage doubler circuit those first two caps are in series. That means their voltage handling capability goes up but the net capacitance is halved. The 500V rating is a bit of overkill; it’s not uncommon to see a pair of 300v caps there. Also not uncommon to see 220uF used.

On the other hand, Kegger really new what he was doing..... and if he picked those values it was for good reason. As a first build you would do well to at least start as drawn.
 
Gotcha. Thanks for pointing out the series cap relationship. I've read tons of stuff since I've become interested in diy audio but it's not until I work on something myself, and have someone else point out the things I'm overlooking, do I really learn. Going to a lower voltage opens up some possibilties as well. Again, thanks for your help!
 
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