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I found a nice old portable CRT TV (model "tele star 4004") without a power cable.

The power socket on the back has six pins:

socket

I've never seen such a design before (and google is coming up short). I need to replace the power cable but to do this I need to identifying which pin does what. (I realize the hazard of messing with CRT units and I'm taking precautions)

This is the schematic for the power input:

schematic

My experience with power supply inputs is simple two-wire positive/negative rails so this is a bit beyond me

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That diagram is showing you two power options.

  1. Mains uses a cable with 220 V AC on pins 5 and 6. Note that there is a jumper connection on 3 and 4 so I suspect that 12 V DC comes out on 3 from the transformer-powered internal DC supply and is fed back in on 4. (It could just as well be fed back in on 2 as they are connected internally.

  2. Battery uses a cable with negative on 1 and positive on 2. The 3 - 4 jumper is not required in this case.

You have two options:

  1. Open it up, find the mains wiring going to FU1 / S1, disconnect those from the power socket and feed them directly from a new mains cable and plug. Make sure that the original mains input pins are disconnected because they will be exposed.

  2. Get a 12 V power supply and feed these in on 1 and 2 (observing polarity). The TV, at a guess, is going to need 5 to 10 A from the 12 V supply. You could check it on a car battery and, if it works, measure the input current using a multimeter on the 10 A range in series with the TV. Based on this experiment you can determine what power supply to use - if it's worth the expense.

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  • \$\begingroup\$ The problem is that we don't know which pin is which on the connector. \$\endgroup\$ – Dave Tweed Oct 14 '18 at 13:08
  • \$\begingroup\$ And when it needs more than 10A and the meter has a fast fuse... \$\endgroup\$ – PlasmaHH Oct 14 '18 at 14:20
  • \$\begingroup\$ Agreed. The high-end meters such as Fluke have a time rating for 20 A on the 10 A range. I can't remember the numbers but there's a certain number of seconds of use and then a cool-off period. \$\endgroup\$ – Transistor Oct 14 '18 at 14:45
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Just open it up and trace the wiring. It should be pretty obvious which pin is which by matching them up with the schematic.

But even without opening it up, I'd be willing to bet that the two pins with the greater spacing from the other four are the 220VAC pins (pins 5 and 6). You can verify this by checking for continuity to the terminals of the fuse holder. You might be able to find a 2-pin line cord that fits these pins directly.

Of the remaining four, two are shorted together, so they're the +12VDC (pins 2 and 4 — this tells you which side of the connector has the even numbers).

The last two (pins 1 and 3) are ground and +12V from the internal power supply. One of them (most likely the one in the corner) will be shorted to some other ground on the chassis, such as the head of a screw, or an earphone or antenna jack. Or you could apply AC power and see which pin has +12V on it relative to the rest — that's pin 3.

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