UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Half wave mains rectification and live chassis in Australia and New Zealand?.

winston_1 · 2nd Jul 2020, 11:56 am

Recently came across on an electrical forum the fact that half wave rectification of the mains was not allowed in Australia.
Some quotes:

"While I do not know concerning the "Regulations" in the UK, any device which provides only "Half Wave" rectification is not allowed to be connected to the "mains" in Australia. However, if the Rectifier is only "Half Wave", the Mains supply will be "loaded" at only every "half cycle". (Power supply authorities do not like this - for rather obvious reasons.)"

"As far as I am aware, all (Cathode Ray Tube) CRT TVs sold in Australia had a "mains" transformer.
The "high voltage" secondary of these transformers was "centre-tapped" and the DC was obtained via a "full wave" rectifier, such as a 5Y3GT.
(Yes, I do know that anything less than 1000 V AC is "low" voltage, according to IEC definitions.)

Of course, later designs (and, probably, all colour TVs) utilised solid state components, including "Full Wave" (Bridge Rectifiers) but these always included a "mains" (isolation) transformer - for "safety" reasons - and the transformer was required to provide the "heater" voltage for the CRT."

"(This post has sent me back looking at books and manuals which I still have from the 1970s and before.
e.g. "Miniwatt Technical Data" 1958 and "The MAZDA Book of Pal Receiver Servicing" 1971.)"

I was quite surprised to read that as I thought UK sets were exported down under before the Japanese invasion. Does anyone have any more information on this and did this also apply in New Zealand?

2nd Jul 2020, 11:56 am	#1
winston_1 Hexode Join Date: Oct 2012 Location: London, UK. Posts: 498	Half wave mains rectification and live chassis in Australia and New Zealand?. Recently came across on an electrical forum the fact that half wave rectification of the mains was not allowed in Australia. Some quotes: "While I do not know concerning the "Regulations" in the UK, any device which provides only "Half Wave" rectification is not allowed to be connected to the "mains" in Australia. However, if the Rectifier is only "Half Wave", the Mains supply will be "loaded" at only every "half cycle". (Power supply authorities do not like this - for rather obvious reasons.)" "As far as I am aware, all (Cathode Ray Tube) CRT TVs sold in Australia had a "mains" transformer. The "high voltage" secondary of these transformers was "centre-tapped" and the DC was obtained via a "full wave" rectifier, such as a 5Y3GT. (Yes, I do know that anything less than 1000 V AC is "low" voltage, according to IEC definitions.) Of course, later designs (and, probably, all colour TVs) utilised solid state components, including "Full Wave" (Bridge Rectifiers) but these always included a "mains" (isolation) transformer - for "safety" reasons - and the transformer was required to provide the "heater" voltage for the CRT." "(This post has sent me back looking at books and manuals which I still have from the 1970s and before. e.g. "Miniwatt Technical Data" 1958 and "The MAZDA Book of Pal Receiver Servicing" 1971.)" I was quite surprised to read that as I thought UK sets were exported down under before the Japanese invasion. Does anyone have any more information on this and did this also apply in New Zealand?