ZX80 PSU (black) with no jack plug

[Lardo Boffin]

I have recently bought a zeddy with a ZX80 PSU (black) that has no jack plug on the end of the cable. I have checked it with a multi-meter and it is producing 13.8V - is this about right when not under load?

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Do I need something like this for the plug?:-

http://m.ebay.co.uk/itm/20Pcs-3-5mm-Mal ... Ciid%253A1

I don't need 20 of them but they are closest looking to the originals I can find!

Also when wiring it up there is a black wire and another with a white stripe on it. Which one goes to which part of the jack plug? I know I should probably be able to work that out but would not like to get it wrong....

Many thanks as ever!

Lardo

[Andy Rea]

my good zx81 supply makes 14v unloaded an d 11.5v at the socket when plugged into a zeddy
the supply i actually use day to day makes 12v unloaded, 9.2 at the socket when plugged into a zeddy

the tip of the jack is positive

regards andy

[1024MAK]

ZX80 PSU - details of the unit I just looked at:

The circuit is a conventional PCB mounting mains transformer, discrete bridge rectifier (looks like four 1N4002 diodes, but I can't see all of the type number) and 1000uF 16V electrolytic "smoothing" capacitor.

Under the transformer, it looks like there is a thermal fuse. But again, I can't see enough to be certain (could just be a PCB mounting normal fuse).

On the unit I looked at, the positive +9V wire was black with a white strip, while the 0V wire was plain black. But if you have a multimeter, you can test this. If the red probe is connected to the positive wire, and the black probe is connected to the 0V/negative, there will be no polarity indication on the meter. Swap the meter probes/leads around and you will then see a negative/minus sign in the display on the left hand side.

The open circuit output voltage was tested and found to be 13.78V. Later when I tested again it was 14.01V. This is typical of this unregulated DC type power supply design, as it will vary a bit depending on the current mains voltage.

When disconnected from the mains supply the voltage should drop slowly. This is what occurred with the unit under test. So the capacitor passes this very basic test.

The output 3.5mm jack plug has the following polarity: Tip is positive +9V, sleeve is 0V

I hope this helps

Some photos...

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ZX80 power supply unit - front showing label

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ZX80 power supply unit - inside, side view showing transformer and capacitor

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ZX80 power supply unit - top view of inside showing the mains input wires

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ZX80 power supply unit - inside showing the four diodes

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ZX80 power supply unit - inside, showing the other side of the transformer

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ZX80 power supply unit - bottom view of inside showing the capacitor

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ZX80 power supply unit - showing PCB track side

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ZX80 power supply unit - showing PCB track side at an angle

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ZX80 power supply unit - 3.5mm mono jack plug without cover

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Mark

[tokabln]

Not sure if you are living in UK...

then for example Reichelt could be a distributor for you as they ship to UK as well

https://www.reichelt.de/ADW/0/0/index.h ... ANGUAGE=EN

If you are talking about a ZX81... something like the following is needed

https://www.reichelt.de/Jack-Plugs/KS-3 ... 5mm%2Bmono

I believe you will find something similar at a local UK electronics distributor.

Have fun

Torsten (Germany - Berlin)

[1024MAK]

Photos now added to my earlier post above

[1024MAK]

Do I need something like this for the plug?:-

http://m.ebay.co.uk/itm/20Pcs-3-5mm-Mal ... Ciid%253A1

I don't need 20 of them but they are closest looking to the originals I can find!

Yes!

That's a good price, so you may as well buy twenty, then you will have nineteen spares

Mark

[Lardo Boffin]

Thanks for the info all.

20 have been ordered. If anyone needs any am happy to pass some on for the price of p&p. So long as people don't need 20 of them...

[1024MAK]

Additional test data:

With a 12V 4W lamp as a load, the output voltage was 11.25V (output current being 335mA).

Note: the above results were done using a non-RMS meter.

Mark

[Lardo Boffin]

I have had 2 mins to check this and the the wire with the white stripe is positive on mine. It typically produced between 13.9 and 14.02V. The voltage dropped slowly after unplugging - surprisingly slowly!