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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

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Old 15th Mar 2016, 12:34 pm   #1
'LIVEWIRE?'
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Question 'Do not use Metal Cased batteries' in 1960s Radio - Why?

I'm currently in the process of repairing a World radio 'Playmate' 7-transistor portable radio, and have just noticed that, on the label inside the case it states 'Warning'-Do not use Metal Cased Batteries', and the word 'Warning' is in unerlined upper case letters. This is a typical mid 1960s radio, using 3 x AF117, with a 4-transistor amp. made from OC71. 81, and the like. The PCB is mounted on a metal frome, but as the internal cells of any battery are surely insulated from it's case, I'm wondering what problem/fault would be caused by the use of a metal cased PP6. Does anyone know? (I'll post some photos later, btw)
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Old 15th Mar 2016, 12:51 pm   #2
Nickthedentist
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Default Re: 'Do not use Metal Cased batteries' in 1960s Radio - Why?

As a 5 year-old in the late 1970s, I had a Thomas Salter electronics kit which had a simple AA battery holder made from two strips of plated metal bent into L-shapes, attached to the baseboard with cheesehead screws which also made the electrical connection to hidden leads.

There was no such warning, but when used with a metal-clad Duracell, the screw heads bit through the paint, the cell was short-circuited by its (otherwise isolated) metal case, and became dangerously hot. I wrote a letter to the company, but they didn't even have the courtesy to reply!

Could it be that the battery casing could rest against a PCB etc. causing a short circuit?

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Old 15th Mar 2016, 2:22 pm   #3
'LIVEWIRE?'
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Default Re: 'Do not use Metal Cased batteries' in 1960s Radio - Why?

The radio is built on two PCBs attached to a metal frame, with the Positive line common to the metalwork, so Iguess there's a possibility that a s/c could happen.
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Old 15th Mar 2016, 3:37 pm   #4
camtechman
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Default Re: 'Do not use Metal Cased batteries' in 1960s Radio - Why?

Not so long ago I remember a similar s/c problem that could occur when Duracell & other brands of alkaline batteries were used when the toy Star Wars Light Sabre came on the market.

This was due to a sharpish edge along the common part of the battery holder which could cut into the outer wrapping, thus causing the s/c and the battery/s to get hot.

As a result, a safety warning was announced, followed by a recall.
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Last edited by camtechman; 15th Mar 2016 at 3:46 pm.
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