Audio Research D70 mark1 + schematic

Take a look at the Audio Research Corp. Database (ARCDB) at http://www.arcdb.ws Look under Amplifiers, then D-70. At the bottom of the D-70 page are a couple of schematics. Can't be sure which model, Mk I or Mk II, but the date is 1982/1983. They are hand drawn so I don't know the source and I doubt ARCDB knows either. They just post pictures people provide. Very doubtful you will get anything out of Audio Research, so good luck!

Stewen1, I believe IF your D70 uses the 6FQ7's then it is a mk 2 version.
You could check with ARC themselves, they are VERY helpful when it comes to the amp and still service it. I don't believe Pmotz is correct in his assessment of ARC service.

Thanks for answers ! Well , the schematic at www.arcdb is
an early mark 2 vesion with R13,R14 511 ohm and R12,R15 110 ohm . "My version has 1,5K for these resistors and its very
sensitive when I´m trying to set the +90V with the trimpot.
Can´t read the value of the trimpots ( four total) but when I measure it might be around 20K . The mark 2 version has 5K trimpots and I think it is much easier to set the "workingpoint" for mark2 amps. Do You think I should try a
modification here ? As I have found there are at least three
or probably more versions of the D70 model.

Stewen 1, I don't think there are multiple versions of the Mk2. My D70 was updated at the factory to Mk2 status, which the factory still has record of.
You might check with ARC, as previously suggested, to get more info on your amp....just give them the serial #.

I wasn't inferring Audio Research service isn't good, just that I doubt they would "give" you a schematic. They may be more than willing to sell you one, if they have it. I assumed Stewen1 was looking for a quick and easy freebie, so that's why I made the comment. Since the dawn of (Audio Research) time the only way to contact them was on the phone or snail mail, no e-mail, let alone downloads. I hadn't been to the Audio Research website in a while, I normally go direct to ARCDB since there is more information there, but I took a look just now and was surprised to see they now offer downloads of manuals. Welcome to the 00's Audio Research! (I'm being facetious). For Stewen1, the bad news is the D-70 is not included.