UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Britannia B1014R

Techman · 3rd May 2021, 11:09 pm

Thanks chaps.

R56 was actually there when I looked closer. There's voltage both sides of R28, 10 ohm. A scope test showed there was audio at the output pin 12 of the TDA which rose and then disappeared with adjustment of the volume control. Looking at the data sheet for the chip shows there's a lot more going on inside it than is indicated in the simplified block shown on the diagram. I'll look at the possibility of the detector coil adjustment, but other than that it's looking like the chip itself. I see they're available quite cheap, although I may actually have one - I'll have to have a look in the loft if I can face looking through boxes of old chips, all out of order, that I was given a few years ago by a chap that must have had a misspent youth stripping components from hundreds of old boards. He was having a clear out due to getting married and moving into a new home with his wife, so gave me 'half' (so he said) of his stock. There's not enough time left in life to sort all these chips and other components into some sort of order and list them all so that I know what's what, although I've sometimes found what I've been looking for with just a casual rummage. At least the chips are separated and all together in several containers and I know the physical size of what I'm looking for, so I may get lucky, but a couple more tests to be made first.

3rd May 2021, 11:09 pm	#5
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Britannia B1014R - Fidelity chassis Thanks chaps. R56 was actually there when I looked closer. There's voltage both sides of R28, 10 ohm. A scope test showed there was audio at the output pin 12 of the TDA which rose and then disappeared with adjustment of the volume control. Looking at the data sheet for the chip shows there's a lot more going on inside it than is indicated in the simplified block shown on the diagram. I'll look at the possibility of the detector coil adjustment, but other than that it's looking like the chip itself. I see they're available quite cheap, although I may actually have one - I'll have to have a look in the loft if I can face looking through boxes of old chips, all out of order, that I was given a few years ago by a chap that must have had a misspent youth stripping components from hundreds of old boards. He was having a clear out due to getting married and moving into a new home with his wife, so gave me 'half' (so he said) of his stock. There's not enough time left in life to sort all these chips and other components into some sort of order and list them all so that I know what's what, although I've sometimes found what I've been looking for with just a casual rummage. At least the chips are separated and all together in several containers and I know the physical size of what I'm looking for, so I may get lucky, but a couple more tests to be made first.