Dansette RT-66 transistor radio 1962

Dansette RT-66 MW + one LW setting

Dansette are more known for their classic portable record players of the early 1960's and the screw up legs that fitted underneath at a slight angle than radios, although the classic clear tuning knob design with a carry handle was the more well known. This one I'm repairing today is the not so common RT-66. Using 3 x AF117 transistors for the RF stages (with screen wire removed - so more reliable - these can short to components inside with time) made it quite a sensitive front end, with 3 x OC81's in the push-pull output stage gave a lower than normal background noise level. Two models I've found on line are red/cream and white/blue. It was supplied in a nice presentation box with an aerial plug and carry strap.

This arrived, as most 50 year-old radios I buy, being very dusty inside and with an electrical fault. The radio was dismantled by two small screws at either end of the printed circuit board and a nut in the center that doubles as a screw retainer for the back cover. The loud speaker is loosely held in place by the hole in the printed circuit board, so both front a rear can be parted for cleaning. This was done with plastic polish, the same stuff that is used for Bakelite, found on-line in a toothpaste sized tube.

Component layout for  Dansette RT-66 /RT-77 

Vacuum cleaner was applied to the printed circuit board and speaker cone, removing 50 years of accumulated dust. I always take photos before cleaning, just in case something falls off, you can check photos to see where it belongs. While apart Ambersol 40+ can be sprayed into the volume control (just a tiny amount), I find cheaper cleaner spays only last for a short while.

Time to connect battery and guess what? it's as dead as a Dodo, first I always check the speaker earphone socket switch, it's built into the socket itself and very often will be open circuit (O/C). This can be cured by running fine emery paper (sandpaper for metal use) between the contacts to clean them. Check the on/off switch on the volume control, these become tarnished too (use a test meter).

Sold originally in a window display box

If you haven't got a signal generator to trace the faulty circuit or an oscilloscope, then a good thing to check first are the large value electrolytic capacitors, as the electrolyte inside will evaporate with age (causing them to go low in value). They are wired with a polarity so make sure you don't fit one the wrong way around. They can quickly be checked for O/C by bridging them with a 'check component' of similar value. Today the third capacitor I checked was dead, C17 (30 uF) found in series with the loudspeaker. (see circuit diagram)

Print side with tuning logo removed

When the tuning capacitor is tuned fully to the right end of the dial it activates two switches that add components to the radio that will tune it to 1500 meters on Long Wave. At the time of production this was the only UK station on that band (The Home service), and today it's BBC Talk Sport.

CD cover inspired by Dansette name

My radio crackles badly when adjusting the Medium Wave band, I suspect that the mica spacer washers in the tuning capacitor have cracked and a shorting the vanes out intermittently. This component was made by Plessey [on layout shown as GANG] and is very unusual as it has a switch for LW fitted, so I left it alone. (One day one may turn up) If the caps aren't doggy in your radio then test equipment may be required to trace the fault, testing one stage at a time with a 470 kHz signal generator through the first three RF stages and an audio generator for the amplifier section - it's a fine looking radio and well worth restoring so good luck!