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Re: How to build a creatiVision power supply

Posted: Mon Apr 17, 2017 3:03 am
by MADrigal
Mate, there is no "+" and "-". The power supply is AC (alternate current). You have positive/negative on DC only.

I am unsure if you can use one single transformer to obtain two power lines. In my case I utilised 2 separate transformers and that worked 100%.

Re: How to build a creatiVision power supply

Posted: Mon Apr 17, 2017 4:04 am
by mark-emark
Ahh makes sense, I reiterate my first sentence last post about being a novice :lol:

My experience is replacing capacitors on old consoles, re soldering, and car electronics (hence the +/-)

I appreciate your help mate, you're an absolute legend.

P.S. Maybe I should complete and electronics course before I kill myself.

Re: How to build a creatiVision power supply

Posted: Mon Apr 17, 2017 4:08 am
by MADrigal
hahaha
i am no legend.
my experience is very limited too.
your mistake about AC and DC is very common, because most of the videogames power supplies are AC-to-DC.
in the case of CreatiVisions, the power supply is AC-to-AC. but because the console operates with DC internally, the "AC-to-DC rectifier" circuit is in the console PCB.
with other consoles (Atari 2600 for example) the "rectifier" is built with a "bridge of diodes" internally in the power supply.... or at least that was in my old Atari 2600 console. :)
you are most welcome to ask for help and show your progresses.
we look forward to read your impressions on the creativision, once you repair it and enjoy it :)

Re: How to build a creatiVision power supply

Posted: Mon Apr 17, 2017 1:02 pm
by Scouter3d
Hi,

Looking at the CV circuit diagram i think a transfomer with multiple taps (18V and 9V centertapped) like the one mark-emark uses should work!
both voltages go directly to their own set of rectifying diodes so there should be no "interference" between them.

(The Ti-99 4a also uses only 3 wires to feed the console with 9V AC and 18V AC)

Only be sure to connect the currents to to right side of the plug or the CV will burn the internal 7805 regulator...

Greetings TOM:0)

Re: How to build a creatiVision power supply

Posted: Fri Apr 21, 2017 6:34 am
by mark-emark
I made a mistake with the transformer, turns out the 0v isn't centre tapped so I'm assuming that's what caused the issue I just had :( :oops:

I wired it all up and triple checked using my multi-meter, the 18v was actually 19.2 and the 9v was a little high too but as it was not under load, I assume that's as intended. I had it wired as per the diagram but as I said the transformer I used was only centre tapped for 12/24V & 15/30V (at 12V & 15V taps).

Once I turned the power on I cooked the console and the transformer, both were smoking. Looking at the console it looks like it was only 1 diode that is burnt so hopefully I can replace it (maybe the 7805 regulator as mentioned by Tom).

The transformer now smokes even without anything wired to the secondary, just the 240v primary on it's own. It also is only putting out about 3V at the 18V tap and about 1V on the 9V tap. I have enough time to measure it before it starts smoking.

Just another step in the adventure I guess, I'm putting it here so hopefully someone else learns from my mistakes. The transformer I used was suggested earlier in this thread by someone else who didn't end up building one, so if someone else is reading this for guidance - this transformer will not do both voltages.

Cheers, Mark. :cry:

Re: How to build a creatiVision power supply

Posted: Fri Apr 21, 2017 8:58 am
by Scouter3d
Oh Noooo!
Maybe there is a fault (short) on the console, that caused the PSU to fail in the first place?

Please make o picture of how you connected the transformer to the 5pin Din socket

Frying diodes takes a lot of current / voltage surely...

Dumb question: you did use the multimeter in AC mode to measure?!?

TOM:0)

Re: How to build a creatiVision power supply

Posted: Fri Apr 21, 2017 10:10 am
by MADrigal
It well may be the 7805 is gone, still easy to replace. Hopefully that's the only damage occurred internally.
Good luck and cross fingers on your next attempt. Please dont give up! :)

Re: How to build a creatiVision power supply

Posted: Thu Apr 27, 2017 6:27 am
by mark-emark
Thanks guys, I won't give up but i may put it on hold for a while :)

Yes definitely used the multimeter in AC mode, I would have gotten pretty much nothing in DC mode (I've done it before :) )

Here is the way I wired up the transformer, I've tried to make it a little bit clearer so rotated the 5 pin din in the picture.
power supply.png

Re: How to build a creatiVision power supply

Posted: Thu Apr 27, 2017 12:51 pm
by MADrigal
OK just to make sure that everyone understands your diagram: that is a NON-working adaptor! Is this correct? :)

Re: How to build a creatiVision power supply

Posted: Fri Apr 28, 2017 3:17 am
by mark-emark
That is correct, this fried the transformer and console. :oops: