ITT Featherlight super 12 - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

davegsm82 · 15th Jul 2013, 1:26 pm

Quote:

Originally Posted by Welsh Anorak

....The set had been working with no faults, non-stop, for goodness knows how many years! Electricity was cheaper then...
Glyn

I had the same thing with a Strad 10B Radio I received as a gift, the set had been running non-stop apparently in someone's shed for about 25 years. The only time it had been switched off was when the power had gone off a couple of times.

I would have thought the Valves would have ALL gone flat by then, but apparently not.

Dave.

Welsh Anorak · 15th Jul 2013, 2:52 pm

Hi
Isn't there another chip somewhere in the IF? I'd have a look around the AGC circuit, especially as the phantom twiddler's been there.
Re the above post - his could make an interesting new topic - whether electronics last longer by being left on or cycled.
Glyn

Lloyd 1985 · 17th Jul 2013, 8:34 pm

Well, I finally had some success! I ran through the alignment procedure, which on my service sheet is as clear as mud, tells me to connect a voltmeter to test point (J), but test point J isn't marked on the circuit, unless I'm just not looking hard enough! I looked at the circuit for a VC400 chassis set, which also uses the MC1330p chip, that although different said connect the voltmeter to pin 1 of the IC, so I did that and got it all aligned as best I could with my battered signal generator. Upon disconnecting all the test equipment and switching it back on I was rewarded with snow! I tried it with a UHF modulator but still got nothing, so then continued to run through the rest of the alignment.

The bit for aligning the band pass filter is also as clear as mud, as all the coils in it are not labelled as to which one they are either! after a bit of guess work (which was probably wrong....) I'd lined that up too, and the snow had gone from the screen, but on tuning around now I managed to get a slightly garbled picture! So it looks like the IF stages and the tuner are ok, just heavily twiddled

I did at one point manage to get a locked clear picture, but lost it after tweaking one of the band pass filter cores

Anyway, Here's some pictures!

Regards,
Lloyd.

15th Jul 2013, 2:52 pm	#22
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,927	Re: ITT Featherlight super 12 Hi Isn't there another chip somewhere in the IF? I'd have a look around the AGC circuit, especially as the phantom twiddler's been there. Re the above post - his could make an interesting new topic - whether electronics last longer by being left on or cycled. Glyn

17th Jul 2013, 8:34 pm	#23
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,820	Re: ITT Featherlight super 12 Well, I finally had some success! I ran through the alignment procedure, which on my service sheet is as clear as mud, tells me to connect a voltmeter to test point (J), but test point J isn't marked on the circuit, unless I'm just not looking hard enough! I looked at the circuit for a VC400 chassis set, which also uses the MC1330p chip, that although different said connect the voltmeter to pin 1 of the IC, so I did that and got it all aligned as best I could with my battered signal generator. Upon disconnecting all the test equipment and switching it back on I was rewarded with snow! I tried it with a UHF modulator but still got nothing, so then continued to run through the rest of the alignment. The bit for aligning the band pass filter is also as clear as mud, as all the coils in it are not labelled as to which one they are either! after a bit of guess work (which was probably wrong....) I'd lined that up too, and the snow had gone from the screen, but on tuning around now I managed to get a slightly garbled picture! So it looks like the IF stages and the tuner are ok, just heavily twiddled I did at one point manage to get a locked clear picture, but lost it after tweaking one of the band pass filter cores Anyway, Here's some pictures! Regards, Lloyd. Attached Thumbnails