by EWBrown » Mon Nov 17, 2003 6:26 am
I have an old (and somewhat rusty. musty and dusty) Fisher SA-100 that I rescued from the local dump a few years ago. It had suffered the indignities of some rather crudely performed modifications (mostly around the AC power input), and was missing the bottom cover and cage.
For a few years, it just rested on a shelf in my cellar. last year, I decided to see if it had any life left. I gave it the slow and gentle "bring-up" with a variac, and indeed, it still showed signs of life. The 7189s were a mixed lot, and sounded a bit "off", so I replaced them directly with some Russian made 6P14P-EV tubes, (the only attempt at matching was to make sure that the date codes were the same) and kept the original 7427s and GZ-34 rectifier, and reset the bias. It sounded much better. My original plan was just to salvage the iron and junk the rest, but as it works and sounds decent now, I'll hang on to it. The OPTs don't have the UL taps, so they won't be re-located to another DIY-35 project. The SA-100 has fixed bias, not cathode biasing.
The SA-100 wasn't the only item rescued from the dump, also was a Dynaco PAS-2X, also a bit ugly and slightly "hacked" and a n HH Scott FM mono tuner, which basically needed full re-tubing, which I did and it works great. The PAS-2X was fully operational, just needed to have the pots and switches "cleaned" with TV tuner lube, and all 4 12AX7s were Telefunkens! :D which sounded (and tested) perfect. The collection also included two rather ratty looking speakers, which someone else took, and he told me "you can have that old tube junk, I wouldn't bother with that stuff". I think I came out with the better end of the deal.
/ed brown in NH
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