Total Recall power connections - little help...

[cleaninglady]

I built the Total recall and i seem to have a problem with power connections.

I have a couple of questions about the power for this project :

Firstly is the 24V DC adapter supposed positive tip or negative tip.

I have this positive tip supply : 24v DC 1 Amp regulated.

http://www.altronics.com.au/p/m8968b-powertran-24v-dc-1a-fixed-2.1mm-tip-positive-appliance-plugpack/

Is the power connection as follows :
Positive tip of supply > to jack tip > to positive pad of the PCB ?
Negative sleeve of supply > to sleeve of jack > to negative pad of PCB ?

With this setup , my negative regulator was showing +24V one side and approx +8V on the other side.

I changed it out , the new regulator is showing +24V/+6.65V
I was taking GND from middle pin of regulator for both measurements.

i don't understand whats going on.

[madbean]

The TR is positive ground. It doesn't matter if your adaptor is negative or positive tip. All that matters is that from the DC jack, you wire the +24v tip to ground on the TR PCB (the square pad) and ground from the DC jack to -24v on the TR PCB (the round pad). So, when you measure the voltage directly on the TR PCB you will have -24vDC with respect to ground.

[m-Kresol]

With this setup , my negative regulator was showing +24V one side and approx +8V on the other side.

I changed it out , the new regulator is showing +24V/+6.65V
I was taking GND from middle pin of regulator for both measurements.

what's important when you measure voltages here, you still need to attach your black probe to GND, even though it's the positive side, and the red probe to the point you want to measure. otherwise you'll always get positive voltages on your multimeter.

[solderfumes]

Just to be sure, are you using a plastic DC jack?  I know you were asking about using a metal one and I said it would be OK, but not if you have a positive-tip adaptor.

[cleaninglady]

Thanks all.

I think i was measuring wrong although i had it wired correctly. I'll test again and get back to you.

solderfumes - For now , i'm using a metal DC jack but it's not mounted in the box so as not to cause problems

[cleaninglady]

Just tested it again the right way.

Getting around -23V on the input of the 7915 and -16.5V on the output.
Is that output voltage a bit high or within an ok range ?

I assumed the centre pin of the 7915 was GND and left was input and right was output.
My mistake. Should have checked the data sheet.

[Martan]

Pretty sure that voltage is ok (-16.5) until you put a load on the regulator. Check the ic sockets (no ics loaded) for power and ground.