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Desperately seeking circuit. S.T.C. 56D
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Return to top of page · Post #: 1 · Written at 7:22:57 PM on 14 January 2017.
	Labrat Location: Penrith, NSW Member since 7 April 2012 Member #: 1128 Postcount: 385
Dear Friends. Around twenty-five years ago I was given an S.T.C. console radio. At the time I tried to find a circuit for it but had no luck. Now with the aid of the Internet, and the words, "Google is your friend" ringing in my ears, l again looked. Still no luck. I have found only that it was made in 1934 is an AC/DC set and that it has an IF of 460kcs. It might possibly be listed as model 562D although that is not what is on the label on the rear. It has only two knobs on the radio. Please help. Wayne.

Return to top of page · Post #: 2 · Written at 8:09:58 PM on 14 January 2017.
	GTC Location: Sydney, NSW Member since 28 January 2011 Member #: 823 Postcount: 6761
What's the valve line-up? Also, a photo or two could be helpful.

Return to top of page · Post #: 3 · Written at 9:32:59 PM on 14 January 2017.
	Labrat Location: Penrith, NSW Member since 7 April 2012 Member #: 1128 Postcount: 385
Valve line-up as follows 12Z3, 43, 6C6, 6D6, 6C6. As I am writing this on my telephone and the uploader is not yet operational the photo might take a while to come through.

Return to top of page · Post #: 4 · Written at 8:19:15 AM on 15 January 2017.
	JFB Location: Milton, NSW Member since 27 June 2016 Member #: 1945 Postcount: 55
According to the radio models list on the HRSA site (http://www.hrsa.asn.au/) it may be a 562D with chassis 56D manufactured in 1934. However http://www.radiomuseum.org/r/stcaus_562_ch_56.html has the valve line up as 57 58 57 2A5 80. There is a circuit diagram there if you are a member. A copy of Peter Lankshear's article on restoring a 562 can be found here messui.the-chronicles.org/valves/VR198908.pdf it contains a circuit diagram but without component values although many are mentioned in the text. The valve line up in this article is also 57 58 57 2A5 280 Joe

Return to top of page · Post #: 5 · Written at 8:44:29 AM on 15 January 2017.
	JFB Location: Milton, NSW Member since 27 June 2016 Member #: 1945 Postcount: 55
Circuit diagram found Copy sent to your email address Joe

Return to top of page · Post #: 6 · Written at 5:48:26 PM on 15 January 2017.
	Labrat Location: Penrith, NSW Member since 7 April 2012 Member #: 1128 Postcount: 385
Dear Friends. I have subbmitted three photographs of the radio in question. Note, first of all, that the serial number on the paper label on the back cover of the cabinet matches the serial number stamped into the left rear of the chassis. The set has what I believe to be a 6X5 GT rectifier in place of the 12Z3. The other valves are as listed, 43, 6C6, 6D6, 6C6. I am not sure what to make of this set. The label on the rear states that the rear cover is not to be removed unless the POWER PLUG is removed from the wall socket. ie, is not a battery set but perhaps an AC/DC set as stated in one reference. I have not altered it and maybe the chassis was converted to an AC only set later on. Still, the set does not match the valve types listed on the circuit sent to me. Another guess, it was an early production set and the circuit and valves were changed in later production. Any guesses? Still, there must be out there somewhere the circuit to match the valve complment listed on the label on the back of the set. Alright Sleuths, get working. Wayne

Return to top of page · Post #: 7 · Written at 7:32:17 PM on 15 January 2017.
	Ian Robertson Location: Belrose, NSW Member since 31 December 2015 Member #: 1844 Postcount: 2476
Hu Wayne If it"s got a 6X5 there should be a mains transformer. Is there? I have an STC mantle that my late mother was given by the advertising agency she worked for during WW2. Her job was to log the radio commercials to make sure they were getting played. It's also different to any circuit I've found and doesn't match the model number stenciled on the chassis, although the valve legend matches.. As a WW2 build it was probably made from what was available. So it did happen....

Return to top of page · Post #: 8 · Written at 9:12:15 PM on 15 January 2017.
	Brad Administrator Location: Naremburn, NSW Member since 15 November 2005 Member #: 1 Postcount: 7395
Photos uploaded to Post 6. ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾ A valve a day keeps the transistor away...

Return to top of page · Post #: 9 · Written at 10:03:04 PM on 15 January 2017.
	Flakes Location: Adelaide, SA Member since 27 February 2010 Member #: 630 Postcount: 398
Hmmm..... Ok so I would check what happened with the rectifier. The 12Z3 is a 12v,1/2 wave indirect Rectifier. On the other hand the 6X5GT is a 6v Full Wave Rectifier. If there has been no change in transformer: 1st - If its using the 6v winding from the other valves then the transformer may well be overloaded. 2nd - The HT voltage will be very wrong... 3rd - Take lots of pictures under the pan so we can see what happened.... I was thinking it would be a simple Chassis 56 like the one I own but that is completely different. http://www.radiomuseum.org/r/stcaus_561_ch_56.html ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾ Valve radios, They just don't make them like they used to

Return to top of page · Post #: 10 · Written at 12:04:45 PM on 16 January 2017.
	JFB Location: Milton, NSW Member since 27 June 2016 Member #: 1945 Postcount: 55
From the HSRA data, that valve lineup matches the 1935 577D which uses a 57D chassis, which is also used in the 572D they are both listed as AC/DC Broadcast only consoles. The Radio Museum also lists the 570D as using that particular chassis, no circuit diagrams there unfortunately, but these model numbers may be worth exploring Joe

Return to top of page · Post #: 11 · Written at 12:14:49 PM on 16 January 2017.
	GTC Location: Sydney, NSW Member since 28 January 2011 Member #: 823 Postcount: 6761
Unfortunately no schematic references given in the HRSA data for those early STC models.

Return to top of page · Post #: 12 · Written at 3:53:13 PM on 16 January 2017.
	Robbbert Location: Hill Top, NSW Member since 18 September 2015 Member #: 1801 Postcount: 2078
That 6X5GT looks totally out of place in such a nice old chassis. At least a 6X5G would look better.

Return to top of page · Post #: 13 · Written at 5:18:44 PM on 16 January 2017.
	Ian Robertson Location: Belrose, NSW Member since 31 December 2015 Member #: 1844 Postcount: 2476
I have a 6X5G in a 30's car radio. Very rare. That set has been modified, transformer added possibly when the mains power went to AC or the owner moved.....

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