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RCA RS-199 tube amp help/assistance

FarFigNewton

FarFigNewton

New Member
Short time reader first time poster. Looking to get my amp working and happy to find a community that knows about tube amps and especially the tube amp that I have!

The Story of the amp
I acquired a RCA Victor Model IVF346a from my grandma. We used it for about 9 months in our home, we played records on it and such. Amazing sound. Then the audio started to get a womp to it, after some research, I determined that one of the capacitors was going out. Around the same time the turntable was acting up, it wouldn't start when switched on. So I set out to replace the large can capacitor, I found a guy on youtube that had a few options, buy 3 different capacitors, find a vintage capacitor on ebay, or buy a custom can capacitor from a place like Hayseed Hamfest. I opted for a custom can and replaced the existing can capacitor with one I got from Hayseed Hamfest. After I replaced the capacitor I powered it on and the radio lit up and looked like it was working but ever after warming up the radio would only be heard if I turned the volume to 100% and even then it was a faint whisper. I started to replace all the other capacitors but then gave up. What do I need to do to get this amp working?

Skills
I can solder, I'm not great but I can solder. I am a computer programmer by trade but I like to fiddle with electronics, Raspberry Pis, breadboards, and such. I have an understanding of how current works and a basic understanding of various components like capacitors, resistors, transistors, etc. I'm not afraid to jump in and do some work.
I don't have an understanding of amplifiers. I understand in principle that a signal is brought in and it is increased but how the increase happens is a mystery to me.

Tools
Multimeter

Goals
1. Get amp working
2. Get stereo working (I guess that part should be in a different forum)
3. Listen to some vinyl!

Here are a bunch of images of the stereo and the amp
https://imgur.com/a/PjKOqYw

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New capacitor
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Underside of amp
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Close up of the new capacitor and soldering
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Question
There are 4 inputs/outputs. I know one of them but the other 3 are still a mystery to me.
#1 - ?
#2 - Plug from the stereo. I know two are wires for the power switch but not sure what all the other wires are for. Maybe audio from turntable and radio?
#3 - ?
#4 - Audio output to speakers

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so the main filter cap has been replaced, but there are still some rather elderly caps underneath. Those cardboard tube caps really should be replaced too. The Pyramid caps should be subbed with film caps, the other two are electrolytic caps. Can't read the values but it should be on there somewhere if you roll the cap around. On the Pyramid caps, they are not polarized. That stripe indicates outer foil. You can test for this with a scope or an audio amp, but frankly its not that critical and the new parts can go in either direction. I'm prone to using basic yellow Illinois MPW film caps but anything of the appropriate value will work.

The other two are polarized electrolytic caps. Looks like a radial package would actually fit better here. General purpose caps are all you need in this spot, I tend to use Nichicon but anything made by one of the major makers is fine. Just mind the polarity.


If this has a tuner or preamp with it, expect the caps in that to need replacement too. Old ceramic cartridges in turntables can also break down and fail over time. They usually have a rubber "saddle" that the needle lays against to vibrate the generator inside. When that deteriorates the output tanks with it. thevoiceofmusic.com is my usual source for all things ceramic cartridge.

Not specifically familiar with this amp, so keep in mind these are mostly guesses / deductions.

1) looks like a power connector, probably for a turntable or a pilot lamp
2) usually called an umbilical connector. Usually this has the connections to the power switch and feeds power to the preamp or tuner, whichever the unit has.
3) looks like the audio input connector


That one output tube near the can cap looks like it may have gotten proper hot too. Usually thats a leaky coupling cap (those Pyramid jobs). Normally the getter is silver, that see-through brown is sometimes a sign of heat or heavy use. You might be due for a pair of output tubes.
 
Welcome to AK. I can send you a Sams folder which has a parts list and schematic. The file is too large to upload directly but if you check your 'Inbox' on the upper right I'll make arrangements to get it to you. You should be able to identify the connections using the schematic.

As Gadget suggested, the coupling caps and those orange electrolytics need to be changed. I often find that those electrolytics are totally dead.

There really aren't that many parts in this thing. I would just replace every resistor, diode and cap (with the exception of the ceramic caps).

As for parts, Hayseed makes a good product but they are quite expensive. I would have suggested using individual caps mounted under the chassis. It would be easy to mount terminal strips because there are already holes in the chassis to attach them. Too late for that in this case. I only mention it because someone may, in the future, read this thread when restoring the same amp.

Going forward, I'll suggest Digi-Key as a source for parts because they have a free shipping option which can save a lot, especially on small orders. Here's a link with details:

http://www.audiokarma.org/forums/in...hipping-on-parts-orders.739513/#post-10018562
 
@FarFigNewton


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Way to go! a nice detailed opening post. You already have some of AK's heavy hitters chiming in and I'm assuming more will follow. I'm sure they will get you the advice and info needed.

Fingers crossed that all the amp needs is some TLC and some basic maintenance, they are great amps! and as I'm sure you've already noticed there's not a lot under the chassis making it easy to work on.

As to the TT I'm sure that will be addressed once the amp situation gets sorted out.

We like picture here at AK so any pic's of the console itself?

Here's some eye candy if interested

https://www.audiokarma.org/forums/index.php?threads/1960-rca-victor-brochure.924703/
 
@gadget73 Thanks for the info! That was way more information than I expected and so quick! I'll definitely start sourcing some parts.

@FlaCharlie Thanks for the info too! I've looked at Digi-key for some raspberry pi related components, I'll check them out for the parts.

@Dswankey
I didn't want to overwhelm everyone with a ton of pictures but I got some more.

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Welcome to AK @FarFigNewton. I'm also an audio electronics beginner, and a programmer, and also just recently picked up an RS-199B in original condition. Nice to see one in the original cabinet like that. Looks great. I found that other RS-199 thread you commented on first a while back, and after reading about the troubles the guy had getting the additional preamp stage to work just right I decided to just clean it up and restore the circuit components to spec as a standalone unit with modern RCA jacks, since I've got a high-gain preamp that may work well with it and if it doesn't work well for my setup I'll just pass it along to someone else.

I put together a parts list Mouser, which I'll DM to you in case you want to take a look. The grayed-out items are things you won't need (replacements for the can cap and pieces for converting it to standalone use) and mine is an RS-199B, not an A. But maybe it'll be of use. All the values are stock except I'm bumping the two voltage doubler caps (the big paper ones under the chassis) from their original 100µF to 220µF. I'm also replacing the ceramic feedback caps with fancy-shmancy $3 mica caps. I hear/read you can probably leave ceramic caps alone if you want, as they rarely go bad. But I also hear they don't sound the greatest, so since I'm replacing everything anyway I thought I'd try the mica out.

I can confirm that @gadget73 Is right about #3 above--that's the audio input.

Looking forward to seeing how yours turns out! You're in good hands here.
 
On second look I can't DM you the parts list since it's an XLS. If you want to DM me an email address I can send it over.
 
@robgobson Hey thank you for the info, it’s encouraging that other people have fixed up their amps. I was afraid I had fried the circuits or something and it was a lost cause.
 
meh, not much in there, which makes it fairly hard to really mess up. If it didn't catch on fire almost anything else can be fixed.
 
I don’t, no. I only have the schematic for the B. Did FlaCharlie send you the schematic for the A? If I had that I could compare the two.
 
robgobson said:
I don’t, no. I only have the schematic for the B. Did FlaCharlie send you the schematic for the A? If I had that I could compare the two.
Click to expand...
He did, I had bought a paper one on ebay a while back but it's nice to have a digital copy too. I'll send it to you.
 
Yep, the amplifier circuits of the A and B are exactly the same, so the parts list I sent you should accurate for the A. Unlike for the B, the schematic for the A model does show C85 and C86, which are 8µF crossover caps for the speakers. I can see one of them in the picture of the back, sitting on top of the left hand 3 1/2" driver just behind the RS199A. The cardboard tube thing. There's also a variant listed with two crossover caps, one 8µF and one 4µF. Anyway, those are electrolytics (non-polarized), so they're probably bad and would need to be replaced too (with new non-polarized electrolytics or with film caps).

As @gadget73 already said, you still also have the tuner/preamp to deal with, the RS-1205A on the 4th page of that PDF. That'll be up under that hinged wooden panel and is represented by the drawing on the right side of the label on the back that shows the RS199A power amp on the left. That's a much larger and more complicated circuit.
 
robgobson said:
I'm also an audio electronics beginner, and a programmer, and also just recently picked up an RS-199B in original condition. Nice to see one in the original cabinet like that. Looks great. I found that other RS-199 thread you commented on first a while back, and after reading about the troubles the guy had getting the additional preamp stage to work just right I decided to just clean it up and restore the circuit components to spec as a standalone unit with modern RCA jacks
Click to expand...

I got my components delivered, Mouser was really fast, only took one day to get them. Do you have any pictures of how you laid out the new components in the chassis?
 
I haven’t started on it yet actually. You should be able to just swap each component out one by one—figure out the value of the original, grab the new one and put it in the same spot. For resistors, look up how to figure out the value from the color bands. Pay attention to the polarity of the rectifiers and the electrolytic caps.

The only components that are a little different from the originals are the two voltage doubler caps. The originals are axial and the new ones are radial so you won’t have to run wires from one side over to the terminal strip where the rectifiers are. The negative on the new ones is the shorter leg with a corresponding white stripe up the side of the capacitor.
 
Last edited:
Was just looking at mine and realized what I posted before about the voltage doubler caps wasn’t quite correct. I updated my post above.
 
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