Trying to add pre-out/main in CA-410 Yamaha

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Hello all,

This is my first post on diyAudio. The national forums did not give enough info. Well they did, but not regarding my question. I've managed to replace the PSU capacitors & repairing the Watt meter lights using led's. The pics:
https://plus.google.com/u/0/photos/117873294320585877005/albums/5848177410188427537

I've studied the schematics a dozen of times. I understand after 4 months of studying (back to physics!:t_ache:) the basics again. About transistors/caps/polarisation etc.) So far for the intro.

I've read this topic on diyAudio:
http://www.diyaudio.com/forums/soli...integrated-amplifier-am-i-thinking-right.html

I've seen pics of the CA-810 in the internet, rear panel, so I gues it can't be that hard. The plan is to add a Rotel "endstufe" to the Yamaha. 😉:
http://www.uni-hifi.de/cms/upload/bilder/hifi_Komponenten/Endstufen/ROTEL_RB_06/RB06_1.jpg

So the question is: Can anyone give me some hints? (best way to learn)

Thnx in advance,

Chris
 
Do you have the schematic? If not - look here: Yamaha CA-410 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine

What you need to do is the following:

Lift the leg of C451 and C452 that is connected to R435 and R436. Then lift the legs that went from the resistors to the capacitors. The legs you just lifted from the capacitors are MAIN IN (for the left and the right channels, respectively) and the legs you just lifted from the resistors are PRE OUT (again, one for each channel).

And that's it.

(At least, that's how I would to it. Probably, someone will correct me after this... hehehe).
 
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This is my first time also with pre-amp and main amp. So if I understand it right the only thin I should have to do is to "lift the resistors" & cut of the main amp. This signal is called "pre-out", is around 2 Volts. So if I would really do it nice i'll just make a switch inside. So when one wants to use the integrated Yamaha amp this will also be possible.

I'm I correct?

I've already seen some crazy Yamaha main amps for about 100 euros. With tone control. It would be really nice if it is this easy to connect one. Is it? 😀
 
Yes, that's all you need to do. The switch thing will work, too.

And of course, doing this will let you use any power amp with the system.

I normally take both pre out and main in, and wire them to four RCA plugs in the back (usually the tape in / tape out -loop, because I don't need that) and connect a short cable between them (or if I have them, those metal links that amps usually come with), for full integrated amp functionality.
 
You can do this with a single 4pole or 5pole plug & socket. Like a DIN or XLR socket.
Wire all 4 lines to the socket poles. Inserting a "shorted" plug gives you a straight through. Or you can use the socket as a line out and Straight through, or as line out only or as line in only.
 
This is really nice. Then I only have to replace the signal/tone caps. But they are mounted upside down for 35 years and the seem to be nice. So that can wait. And I only have to do the thing for the (example) the tape signal path. The tone control are mostly "tantaal" caps. Guess the will be fine to. Just a bunch of solid material. Or I'll visit someone with a oscilloscoop to really see wat have to been done.

Im gonna make it a hell of a beauty. I have seen that Velleman has a simple MP3 dac. 😉

Wait for it. This makes electronics really fun!
 
Tantalum caps in vintage electronics seem to be rather controversial topic. Some claim that they must be replaced as soon as possible, due to them having a dangerous failure mode where they short out (taking out other things in the process), and can even catch fire.

It's probably not going to happen, but it's worth considering.
 
Many thanks guys! Ive uploaded the final pictures. I replaced the cap nr's 443 &444 with Elna's from a donor 930QS Sony. The sound is realy incredible. I had the Yamaha since the DA50ES. Also the Elacs. And I can say that this amp realy kicks ***. Every week there go's 5 bucks into the amp. (ssssst) As long as it plays, or until I have enough for a AS-3000. But I will listen to it first. Im not impressed by MOSFET advertising anymore aldo a fet amp sound really clear. The 930QS well thats another story. Wait for it.
 
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