General Electric T1284A AM/FM Radio Remodel

7/2/2018

A friend of the family gave me this GE T1284A AM/FM tabletop radio. She knew that I restored old radios and thought I would like this one.

The T1284A is unremarkable and is of very common design for a radio from the mid to late 1960s. It is of superheterodyne (superhet) design with an AM IF (Intermediate Frequency) of 455kHz and an FM IF frequency of 10.7 MHz.

It is powered from 117 Volts 60Hz line current, common in the United States, and uses a transformerless design that incorporates a wire-wound resistor to step down the voltage and and a single diode to rectify the current required to power the transistor circuits.

The T1284A incorporates eight transistors, one being of the power transistor type housed in a metal case, that drives the speaker. The audio stage uses a 4 ohm PM (Permanent Magnet) speaker driven by an audio impedance matching transformer.

As unremarkable as this radio was, it did have a handsome wood cabinet and a pretty facade, which motivated me to take this radio on as a remodel project.

Step 1 Disassembly

The first step of any remodel project is to tear down the radio to see what you have to work with. The back cover is the disassembly starting point for the T1284A, one screw, circled in red in the picture below, holds it in place. The back cover fits in a slot, simply pull the back panel down and then straight up to remove.

Below is a picture of the inside of the T1284A.

The Volume, Tone, and Tuning knobs need to removed from the T1284A. They just pull off.

In addition, the AM/FM and AFC switch covers need to be removed.

Two screws, accessible from the back, hold the chassis in place inside the wooden cabinet and need to be removed. There is one in the upper right-hand corner of the cabinet.

The other is located in the upper left-hand corner of the cabinet.

Once the chassis screws are removed, you can tilt the front panel with attached chassis down.

The audio transformer is attached to the bottom of the cabinet. You must first unwind the wire leads from around the transformer in order to gain access to the screws holding it to the cabinet.

Remove the two screws that hold the audio transformer to the base of the cabinet.

You should now be able to pull the back panel through the front of the wooden cabinet. The chassis/front panel and back panel should now be free of the cabinet.

Step 2 Electrolytic Capacitor Replacement

As electrolytic capacitors age, their electrolyte dries up causing their electrical capacity to drop and leakage current to increase. It is definitely a good idea to replace 50 year old electrolytic capacitors like the ones in the T1284A!

Electrolytic capacitors should be replaced with one of similar capacitance and equal or above Voltage rating. These type of capacitors are also polarized so make sure you observe the polarity of the capacitor to be replaced and install new the same way.

I check each replacement capacitor with my trusty GM328 Multi-Function Tester before installation.

The electrolytic capacitors, circled below, were replaced.

One electrolytic capacitor, that was close to the front panel, had to be soldered to the bottom of the printed circuit board. I was able to get the original out but was unable to thread the replacement through the holes in the printed circuit board from the component side.

Here is a picture of all of the electrolytic capacitors that were replaced.

Step 3 Cleaning and Lubrication

The Volume control caused static to be heard from the speaker while be rotated during initial testing. As such, I decided to spray contact cleaner inside both the Volume and Tone potentiometers then rotate them back and forth several times to clean up the contacts and the resistive element the contacts touch.

Both the exterior and interior of the wooden cabinet were treated with lemon-oil base furniture polish.

Mr Clean MagicEraser sponges work miracles on cleaning vintage electrical cords! I apply an Armor All like protectant to the cord after it has been cleaned and dried.

Volume, Tone, and Tuning knobs are cleaned with a toothbrush and water then throughly dried.

No amount of metal polish is going to clean up the AM/FM and AFC switch covers. Their chrome finish is pocked and badly corroded. They will have to be painted.

I used Windex to clean the front panel including the speaker grill. Windex is my go-to universal cleaner.

Q-tips moistened with Windex work great for cleaning crevasses and hard to reach corners.

Look how dirty the paper towel was, just from cleaning the front panel.

I took this opportunity to lubricate the shaft of the Volume and Tone controls as their rotation was very stiff. I use Labelle 107 Oil as it is safe on plastics and I have it around for my model train hobby.

I also lubricated the shaft of the Tuning control.

In addition, I lubricated the Tuning control shaft on the back side of the front panel that connects to the variable capacitor and Tuning dial via a dial cord.

Step 4 Prep and Paint

I am going to paint several things on my T1284A:

AM/FM, AFC Switch Covers
The outer border of the front panel
The silver ring on each knob

The AM/FM, AFC switch covers were wet sanded with a 800 grit sandpaper to smooth out the surface and remove the pock marks due to corrosion.

I mounted the AM/FM, AFC switch covers to the end of Q-tips then degreased their surface with Prep-All. They are now ready for paint.

Two coats of silver paint and the switch covers look like new!

The first step on painting the outer border of the front panel is to mask off everywhere you don't want painted. I use a product called Frog Tape and brown paper to mask off the areas to be painted. Frog Tape has something called PaintBlock which makes crisp lines between painted and unpainted areas. I then degrease the surface to be painted using Prep-All.

Two coats of silver paint were applied to the area of the outer border.

Here is the finished product, once the Frog Tape and brown paper have been removed.

A lot of vintage radios I restore had painted accents on the knobs that have worn off due to normal wear/tear. I have tried to hand paint the accents but my hand is not steady enough and they look "amateurish".
I came up with a new way to paint the accents using a Sharpie Paint Pen and a drill. I mount the base of the knob in the drill and then apply the paint pen while the knob is spinning.

The results look very professional!

Step 5 Assembly

Time to mount the chassis/front panel back into the wooden cabinet. You will need to thread the back panel through the front of the cabinet first.

Time to install the two screws that hold the chassis/front panel to the cabinet. There is one screw on the left-hand side.

Another screw needs to be installed on the right-hand side.

The audio transformer was reattached to base of the cabinet with two screws.

I wrote the model number with permanent marker on the back of the heat sink attached to the chassis.The original sticker on the back panel that held this information had been bleached out by the sun and was unreadable.

During assembly, I noticed that the nut that holds the earphone jack on the back panel was rusted.

I treated the nut to a coat to silver acrylic enamel paint I had on hand for my model railroad hobby.

Time to reattach the back panel. A single screw on the bottom holds it in place.

The AM/FM and AFC switch covers were reinstalled.

I noticed some grime around the holes where the Volume, Tone, and Tuning controls protrude from the front panel. I used a Windex moistened Q-tip to clean.