The Fisher
Model E-49 Electra VII
Restoration

This project came out of an old console piece that was once a fine piece of furniture. As with many electronics these days, there was a need to miniturize so we are rebuilding this for a smaller cabinet. Unfortunately, it was powered on before checking anything, and one of the output tubes was shorted, which in turn took out the output transformer along with a couple other components. To make a long story short, I located a replacement transformer from a chassis found on eBay. For info on why you shouldn't power up older equipment that hasn't been used for a long time, and what I do to prevent catastrophic failures, read this.

Initial Testing

The receiver chassis is a model 590T with a MPX-65 FM multiplexer, and the amplifier chassis model 481A. Tube Layout The parts chassis I found was a model 480A, but the only difference I could find is the umbilical cord connector for the receiver-to-amp harness has fewer wires. In the process of hunting down the T812-217-3D transformer, I did determine the turns ratio of the transformer is 27:1 which gives it an impedance ratio of 729:1. The original three-way speaker system (according to the schematic) was 8 ohms, this would present an impedance of 5.8K to the EL84s.

Testing all the caps on my Sprague Capacitor Analyzer showed them all to be out of tolerance so I replaced them all. Including the power supply filters. (See further down)

The main HV filter was entirely dried out.

So after a new troop of push-pull valves...	...there was some reason why I couldn't get a good signal through them.
They began singing like angels	After realizing the heaters on the phono input tubes I removed and rewired (this will never be used with a phonograph again) were in series as a common-cathode resistor for the finals... ...I added a reststor where they used to be, and...

Frequency sweep of 1000 hz to 5000 hz (I call this my 'Elephant' test.)

With the amplifier operating beautifully, it was on to the receiver. One modification I made was to change the automatic shut-off switch used for the phonograph into a 'Standby' switch to keep the B+ voltage off the plates of the tubes until they were warmed up. This should greatly increase their life.

As I was attempting to adjust the ratio detector, I noticed the secondary slug was difficult to turn. Upon further inspection the ferrite slug had cracked. I was reminded why I pilfer so much stuff from old radios...had one! It was much easier to align with a fresh slug.