In Reply to: RE: Revox A77 Accessories posted by Inmate51 on December 24, 2015 at 16:42:11:
The variable speed option was actually very easy to add. On the Speed Control Card they "replaced" R212/213 with a "divider network" consisting of a 5.1K resistor in series with a 5K linear pot in series with a 6.8k resistor. the center tap of the pot goes to the base of Q206/junction of R215. The 77 I had, had this mod in a little box that plugged into the front of the recorder. Switching contacts in the 1/4" phone jack "neatly reattached" the fixed network when the box was unplugged! Provided -15/+10% speed variation. My notes indicate that this "option" may have (only) been available/made thru the US importer.Charles
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Follow Ups
- RE: Revox A77 Accessories - stellavox 12/26/1506:10:04 12/26/15 (1)
- Easy, or not? - Inmate51 13:57:15 12/29/15 (0)