Monday, July 24, 2006

New Project (Thy name is Fisher)

I am excited to begin my next project. It is now time to restore a 43-year old piece of audio history, a Fisher X-1000 amplifier!

The Fisher
My father bought this in 1963 and had it in regular use for over 30 years. It has been sitting in the basement of my brother's house for the last decade. I am nearly certain that it has not seen the mains in that period, which is good and bad. (The bad part is that capacitors can deteriorate when unused. The good part is that no one plugged it in to try it out slamming it with instant 120V of wall current.)

Amazingly, I don't have much to clean up here. I took off the bottom and inspected the circuitry. It did not appear that anything was wrong (no burnt parts or anything). I think it just got marginalized, and then replaced with new equipment and put away. It had a little bit of dust on it, which I blew off with the air compressor. I will clean it up quite a bit, because I have seen some amazing pictures of shiny equipment.

Not too bad
As you can see, it is already pretty sharp looking. The X-1000 is an integrated stereo amplifier (preamp and amp together) capable of over 50 watts per channel (I think it is technically 110w total). I also have the Fisher K-10 Spacexpander, which is just a pan reverb unit. Ordinarily, I would not really care to bring this back - but there is a control for it on the front of the X-1000! I sort of have to, don't I?

I do have tubes, and the tube shields. I removed the tubes to transport this, because it drove 1,200 miles in my trunk a few weeks ago! If you think you are seeing tubes, they are actually cap cans.

I also got my hands on the Fisher FM 200-B receiver. I will start on that after I get the amp going. Tube receivers can be very complicated because of the oscillating tube, and the tuning of the circuit.

As you can see, I do not have a cabinet for this amp. I will build my own out of something silly like walnut or something. Hopefully it won't be too heavy - because the amp by itself weighs 44 lbs. I talked to my father yesterday about it. He was surprised that I could get over $1,000 for just the amp as it is right now. Restored, tuned up, and in a cabinet, it could fetch $1,500. The tuner could easily go for half that! The reverb unit goes for a few hundred...

What is weird is that I don't have decent speakers. I mean, any speakers I have laying around truly suck. I can't have a high-quality stereo system with sluttish speakers, so I will have to see about that this winter. (I think the speakers that were used with this unit were Wharfedale. I can only dream.)

Here is a short list of what I will do:
  1. Finish cleaning the outside.
  2. Get the schematic and identify the coupling capacitors and order replacements.
  3. Buy a variac (variable transformer).
  4. Replace some capacitors, and the diodes if they are not silicon.
  5. Hook it up to the variac and slowly bring up the voltage. (Folks at AudioKarma suggest 1 hour for every 10 volts until 90, then leave it for a night. Next, put the output tubes in and slowly bring it up to full voltage.)
  6. Measure the voltages and compare it to specs.
  7. Bias the output tubes (there is an external trimpot for this!).
  8. Adjust the negative feedback (DC adjusted with trimpot again).


--gh

P.S. The agreement for removing this from my brother's basement is that I won't sell it. He doesn't have to worry about that!

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