Dynatron TV46F. No sound. - UK Vintage Radio Repair and Restoration Discussion Forum

rbm1973 · 30th Jan 2016, 3:17 am

Before I hunt out the service manual for this set has anyone had issue with no audio although the O/P stage is OK?

TV running through Aroura converter and set to ch3 no audio on testcard or with audio video input.

FERNSEH · 4th Feb 2016, 11:22 pm

The Dynatron TV46F is electrically similar to the Ekco T368F. The Dynatron "Envoy" model TV45 is also similar.
Information for the TV45, TV46F and the Ekco T368F can be found in the 1960/61 Radio and Television servicing book.
The sound stages consist of two Mazda 6F23 IF amplifiers. A 6D2/EB91 double-diode as the demodulator and series noise limiter. The output from the noise limiter is supplied via the volume control to the 30P12 output pentode.
I think your attention should be drawn to the high value resistors which are associated with the noise limiter. Also not above suspicion is the 0.01mfd coupling capacitor which connects the output of the demodulator to the anode of the noise limiter diode.

DFWB.

Freya · 5th Feb 2016, 9:34 am

Could be the interference diode MR2, had this fault before causing no sound. Replaced with IN4148

30th Jan 2016, 3:17 am	#1
rbm1973 Pentode Join Date: Jan 2016 Location: Crewkerne, Somerset, UK. Posts: 119	Dynatron TV46F. No sound. Before I hunt out the service manual for this set has anyone had issue with no audio although the O/P stage is OK? TV running through Aroura converter and set to ch3 no audio on testcard or with audio video input.

4th Feb 2016, 11:22 pm	#2
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Dynatron TV46F. No sound. The Dynatron TV46F is electrically similar to the Ekco T368F. The Dynatron "Envoy" model TV45 is also similar. Information for the TV45, TV46F and the Ekco T368F can be found in the 1960/61 Radio and Television servicing book. The sound stages consist of two Mazda 6F23 IF amplifiers. A 6D2/EB91 double-diode as the demodulator and series noise limiter. The output from the noise limiter is supplied via the volume control to the 30P12 output pentode. I think your attention should be drawn to the high value resistors which are associated with the noise limiter. Also not above suspicion is the 0.01mfd coupling capacitor which connects the output of the demodulator to the anode of the noise limiter diode. DFWB. Last edited by FERNSEH; 4th Feb 2016 at 11:31 pm.

5th Feb 2016, 9:34 am	#3
Freya Octode Join Date: Jan 2009 Location: Falmouth, Cornwall, UK. Posts: 1,989	Re: Dynatron TV46F. No sound. Could be the interference diode MR2, had this fault before causing no sound. Replaced with IN4148 __________________ Stephen _________"It`s only an old telly" ___