exxos's Atari, Amiga & retro forum

Okay, I'm horrible with electronics in case no one has noticed yet :shock: so I've got
another question. It's probably obvious for 95% of the people here but I don't want to
make a mistake and fry something.

I've got this internal Mega STe/STacy adapter from Alan H. for my STacy and it's internal
Ultrasatan.

It has a standard 2 wire power lead using a regular barrel. Well, with the upgrades I'm
doing, it needs a 90 degree barrel to clear where I've mounted the Pico PS. So I've got
one coming from Amazon.

In the picture I'll attach below you can see the adapter is using a blue and red wire. The
90 degree lead has a black and white wire.

So...white to red and black to blue or ?

Thanks everyone.

Just use a multimeter in continuity mode and see which wire goes to the centre of the barrel and which goes to the outside.

Do the same for the replacement barrel and just match them up one for one.

rubber_jonnie wrote: 02 Jun 2024 08:54 Just use a multimeter in continuity mode and see which wire goes to the centre of the barrel and which goes to the outside.

Do the same for the replacement barrel and just match them up one for one.

Thanks, was actually thinking along those lines.

This wouldn't solve the problem though, if say, everything was center +, but the device
you're going to was center- ? I know most aren't but I'm just paranoid. :)

I did find an entry on Jookie's website about the Ultrasatan that says not to worry about
polarity because there's a rectifier...

Thanks for the reply.

Darklord wrote: 03 Jun 2024 00:00

rubber_jonnie wrote: 02 Jun 2024 08:54 Just use a multimeter in continuity mode and see which wire goes to the centre of the barrel and which goes to the outside.

Do the same for the replacement barrel and just match them up one for one.

Thanks, was actually thinking along those lines.

This wouldn't solve the problem though, if say, everything was center +, but the device
you're going to was center- ? I know most aren't but I'm just paranoid. :)

I did find an entry on Jookie's website about the Ultrasatan that says not to worry about
polarity because there's a rectifier...

Thanks for the reply.

You can do the same on the device. Find something you know is ground and then probe the connections on the power input socket. Whichever is ground will buzz out.

rubber_jonnie wrote: 03 Jun 2024 09:07 You can do the same on the device. Find something you know is ground and then probe the connections on the power input socket. Whichever is ground will buzz out.

Right, gotcha - thanks! :)

Okay, continuity check results.

Straight barrel leads I have are Red wire Center +, White wire Outside -.

90 degree barrel leads I have are White wire Center +, Black wire Outside -.

So far so good. Then I get to the internal Ultrasatan adapter, with it's blue
and red wires.

Blue wire is Outside - (strong reading)

Red wire is Center + (strong reading)

However, the Center also gives a weak (halfway on the meter) reading on
the Blue wire.

I have no idea why that would be so? I'm thinking because I'm testing it with
it still attached to the adapter that it's reading like that. I'd almost be willing
to bet that once I disconnect it, it would show straight readings. I'll recheck it
once I actually swap it out for the 90 degree barrel lead.

Thanks.

All the electronics on the adapter are connected to + and -

So you will measure this as a resistance between + and -

LarryL wrote: 04 Jun 2024 05:50 All the electronics on the adapter are connected to + and -

So you will measure this as a resistance between + and -

You beat me to it.

@Darklord if you connect GND to GND you will get a strong buzz with no resistance. If you connect to positive you will see a resistance between positive and GND.

You want the strong buzz with no resistance, then you are connected GND to GND.

Understood - thanks guys. :)

All back together and working fine. Thanks for all the help gang.

Even with the 90 degree barrel power lead, it's a tight fit in there! :)