Museum Hours:

Saturday 10-6

Sunday 12-5

 

Early Electronic Television

Westinghouse WRT-700 Restoration

The Cabinet.  (pictures) The cabinet is in poor condition, and will have to be refinished. Refinishing of the cabinet is complete

The Chassis.  (pictures) There is only one chassis in the set, and it is identical to the TT-5 chassis. This chassis is in good condition, and is mostly complete. Here is technical information.

The chassis will be cleaned with water and a mild detergent using soft brushes to get into small places. Then, all paper capacitors will be replaced with modern ones (see the procedure for this). Each electrolytic capacitor will be tested for leakage and capacity. If bad, new electrolytics will be installed inside the old ones. The high voltage (EHT) capacitor also had to be rebuilt.

The chassis in this set appears to be a prototype. The channel selector shaft is only partially milled, and the fine tuning capacitor has been removed, perhaps to make room for the experimental placing of the shield. There is no serial number stamped on the chassis, and the soldering is less professional than is typical of these sets. Also, the video amplifier tube socket is wired for a 6AC7 or 6AG7. Did RCA originally plan to use that tube, and then decided on the 6V6?

There are several pencil marks to mark the place where holes are to be drilled. These mark the location of holes for the metal shield behind the tuner:

 

There is an extra hole punched out for an IF transformer which was  not used in the production chassis:

 

There is also this marking on the side:

The power transformer is defective, and can't be rewound. I've had a replica made, which is similar, but not identical, in size. I will attach the original transformer covers to the new transformer and then paint the assembly black.

The completed transformer, mounted on the chassis

We now have the power supplies and sweep sections working. We are now trying to get the local oscillator to function. It appears to be wired properly, and all the parts check OK, but it doesn't work.

A bad ceramic capacitor was found, and the local oscillator, IF, and audio sections now work. The next step is to replicate the missing fine tuning trimmer and shaft.

We have made a replica of the original fine tuning assembly. First, a variable capacitor was found that was similar to the original.

 

All but two of the stator plates and one of the rotor plates were removed. Then, a new bracket was made of aluminum. A 1/8 inch brass shaft was soldered to the end of the capacitor, and the joint was covered with heat shrink.

The assembly was installed on the original tuner. The brass rod goes inside the channel selector shaft and extends out the front of the chassis. A piece of 1/4 inch brass stock was cut off, drilled for the 1/8 inch rod, and filed flat to match the fine tuning knob.

Restoration of this set is now complete.