Stern's saville double 6

[mauroelettrico]

Hello,
This ampli for some reason doesn't play on left channel when i turn the selector on STEREO position. If i put the selector on RIGHT BOTH, both channels works but only right input. With LEFT BOTH no sound in both channels. I'm looking for schematics or for a concrete help to solve this issue. I suspect the problem is in preamp section, but i don't know where to put my hands. I replaced some capacitors 4 years ago and It worked very well before this problem. i'll post later some pictures. Thanks and excuse me for my poor english

 

[mastodon]

We need a schematic and any measurement data you recorded. But yeah, it sounds like there's something wrong with the preamp section. Might be as simple as a broken connection, or as complex as parts blowing up due to an unknown defect. In any case, a schematic and some measurements are in order.

 

[mauroelettrico]

I don't know how to start. The only tries i made where made with an oscilloscope and the result was a very low audio signal on broken channel and a low ac sound on speaker. This afternoon i'll do some photos and will ask to my friend to write down a schematic....i hope he will do......
For the information i have now, this ampli uses, 4 ecl86, two per channel. i'll post the exact models and quantity of tubes togheter with pictures.

For information, the exact name of this ampli is STERN'S SAVILLE "DOUBLE 6" STEREO AMPLIFIER

 

[kevinkr]

Suspect coupling caps, corroded contacts, and broken connections first if this effects all inputs.

Can you describe other features? Does it have phono input? Switching: Left, right, stereo and stereo-reverse? Mono? AUX, tuner, tape monitor loop? Phono/tape pre-amp switch?

Clearly the power amps are OK, and something in the left channel signal path is open, but without stating what type of input you used it is hard to know whether this is a line level issue or something else.

Try to locate and post a schematic for us to look at. Google doesn't seem to know anything about this amplifier in a very quick search.

 

[DF96]

I think some Stern amps were copies of Mullard designs.

 

[mastodon]

With 2 ecl86 per channel, it most likely doesn't have a phono input.

Since the power stages are both ok, all the tubes glow. So yeah, coupling caps and bad contacts are the first things to check.

How do all the DC voltages check out; any differences between the channels, esp. in the input/driver stages?

 

[kevinkr]

With 2 ecl86 per channel, it most likely doesn't have a phono input.

Since the power stages are both ok, all the tubes glow. So yeah, coupling caps and bad contacts are the first things to check.

How do all the DC voltages check out; any differences between the channels, esp. in the input/driver stages?

Given the vintage I would be very surprised if it didn't have a phono stage, and a tube rectifier. I took post #3 to mean that the power stages used a pair of ECL86 per channel and that there might be more tubes. Guess we will have to wait for the OP to get back to us on that.

Here is a link to a Stern's that is a copy of the Mullard 10-10 stereo: http://www.hifiworks.co.uk/images_fullsize/sternsmain.jpg
Look anything like this?

Here is another thread here on a Stern's Mullard 10-10 inspired amp, including a picture: http://www.diyaudio.com/forums/tubes-valves/80508-sterns-ecl86-amp.html

 

[mauroelettrico]

I made a check about tubes....i don't know why i said it has two ecl86....
this ampli have these tubes:
4 X ecl83 two per channel
1 X ez81
2 X ef86
1 X 12ax7a.