ETF - RCA TT-5 Restoration

RCA TT-5 Restoration

The Cabinet. (pictures) The cabinet is in excellent condition. All that is needed is some touchup. The touchup has been completed.

The safety glass in front of the picture tube has spots between the two layers of glass. A new one will have to be built. I have made a new safety glass by purchasing a piece of new glass the proper size, masking the screen area, and spray painting the glass the same color as the old one.

The Chassis. Here are pictures and 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.

This chassis is in excellent condition and has already been restored and works, but extensive changes have been made to the original design:

- The power transformer has been replaced with three separate transformers, one for the B+ (HT), one for the high voltage (EHT), and one as a supplementary filament transformer, since the B+ transformer had inadequate capacity.

- The 2X2 HV (EHT) rectifier has been replaced with a 1X2.

- The 5BP4 CRT has been replaced with a 5ABP4, which has the anode connection on the side of the tube.

- There are many modern capacitors, and the HV (EHT) can has been removed.

- A separate FM sound detector assembly has been added

I have sent the transformer from the WRT-700 (which is defective) in to be rebuilt, and to have a copy made for this set.

I have removed the FM sound detector and returned the sound circuitry to the original design.

A replica of the original power transformer has arrived, and I will now return the power supply circuits to their original design. The new transformer has been installed, and the 1X2 has been removed and the 2X2 put back in. Fortunately, the original socket was still there. Whoever restored this set in the past made a plug-in adaptor for the 1X2. A new HV (EHT) capacitor has been fabricated and installed.

Many of the original paper capacitors have not been rebuilt, and there are several modern style capacitors. Next I'll rebuild the old style ones, and replace the new style ones with old ones (I now have a stock of old RCA capacitors, thanks to Chuck Azzalina.)

All the new style capacitors have been replaced with the original style.

This set worked before I began to restore it. However, after replacing the power transformer, I discovered that the high voltage (EHT) was somewhat higher than before (2400 volts vs. 2000). As a result, I had inadequate vertical (frame) deflection. I found that two resistors in the vertical (frame) oscillator section were defective. Replacing them resulted in a fully deflected screen.

I also discovered that the new power transformer has worse magnetic shielding than the original, and caused hum bars in the picture. This set originally had a metal shield around the CRT, but it is missing. I made a temporary shield out of sheet metal, which eliminates the hum bars. Our TRK-5 has its original shield, and I will attempt to get a copy made.