Service manual for Eltrocompaniet AW 3-2

[Henckel]

Hi

I found two Elctrocompaniet AW 3-2( mid 80ties) in a garbage can. Apperently they have been modified for some kind of briding configuration.

In order to restore them back to there original state i could really use the service manual - anybody in for some help ?


What i need is maybee not the full diagram but the value of R39 and R40 as well instructions for setting bias

Thanks

Morten

 

[mbosko]

About bias

Just found this:

"What quiescent current should I use ?
The quiescent current should be calculated from each transitors
Hfe versus Ic curve.
It should be set to no more than sligthly less than half the current
at which Hfe has its maximum.
Lower limit - don't push it too far down"

Hope this will help

 

[Jonathan Bright]

Dear Henckel, The place to start is a web site that has a lot of information on the amp'. Try this. http://home.online.no/~trandstr/AudioStartsHere.htm
I found it by putting something like "Otala amp" in Google. It is a site run by one of the original designers. The schematic that was posted by Mbosko was from an article in a journal of "Transactions in Speech and Acoustics" or something like that and refers to the 1973 original version that was later modified a good deal before it was marketed commercially. The website has the modifications. The original had 600 milli amps (0.6 amp) in the output stage. It ran class A up to about 13db below clipping from memory. But ckeck out the site as I think it will be useful.

I have just tried the site mentioned and ended up with a Sandinavian site (home online) that I could not read. The one I had was in English. Maybe try Google straight away. Try "The Sandstrom Audio Site" that should work or the "EC" homepage.