Sega CDX Actual Output Voltage Amperage Output

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TSX420J
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Sega CDX Actual Output Voltage Amperage Output

Post by TSX420J » Sun Apr 22, 2012 1:03 pm

Does anyone have a real Sega CDX power supply and digital multimeter? If so, can you test the actual output voltage and amps.
I know the label says 9.5v 1.5a but I doubt it outputs exactly what is on the label. I have a Sega Genesis 2 power supply and on the label it says 10v 850ma but the actual voltage is 14.5v!! WTF!!

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Re: Sega CDX Actual Output Voltage Amperage Output

Post by TSX420J » Tue May 29, 2012 2:18 pm

Been testing all of my sega power adaptors with a DMM. What I found is that they all are higher voltage than what is printed on the label. My genesis 1 mk1602 adaptor measures 12.4v rather than the 9v as per the label. All of them measure higher voltages. I was thinking of buying a 12v 1.5a power adaptor instead of going on the hunt or paying too much for a oem or 9.5v 1.5a adaptor. Do you think it would be safe to use a 12v 1.5a adaptor? I can find them for 6 dollars.

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Re: Sega CDX Actual Output Voltage Amperage Output

Post by TSX420J » Tue May 29, 2012 3:25 pm

Found this post on another site;


"sega cdx MK-4122
Input: 120v  60Hz  23w
Output: 9.5v dc  1.5a
positive tip
plug O.D. 4.75mm. I.D. 1.7mm
radio shack adaptaplug type C"

"Also what i need help with is that when i use a multitester to test the outputs of these ac adapters this is what i get:

sega mk 4122 -- 11.5v

Are they slightly higher than what they have on the label on purpose? Can someone check theres with a tester? Only the neo geo was on mark."

For entire thread look here

http://nfggames.com/forum2/index.php?topic=3145.0" onclick="window.open(this.href);return false;

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TSX420J
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Re: Sega CDX Actual Output Voltage Amperage Output

Post by TSX420J » Fri Jun 15, 2012 12:16 am

I bought a 12v 1.5a switching power adapter, connected it to the CDX and ran some tests. I found out that the CDX in Sega CD mode only draws a max of .65 amps when seeking and stabilizes at around .4 amps. So, people that have burned up their CDX's using the Sega Model 2 Adapter, have most likely burned it because of over-voltage and not because of low current. The model 2 adapter outputs around 13.8 - 14 volts on my DMM. It takes some time, but it slowly gets up to 14 volts. I'm running about half a volt more than spec with my 12v power adapter. Does anyone who knows about electronics engineering think that a .5v will fry it in the long run?

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Re: Sega CDX Actual Output Voltage Amperage Output

Post by evilteddy » Fri Jun 15, 2012 8:47 am

Apparently not many people on these forums know much about the Sega CDX :P
In any case, in general many of these older regulators won't be switchmode and as such won't be regulated as you might be used to with modern adaptors. With that in mind its important to measure the voltage and current draw while the system is on. From you only showing the voltage of your power supply (at an elevated level) I assume you were just measuring the power supply while it was open circuit and not powering anything.

TLDR: measure power supplies when they have their load connected. Your '14.5V' supply is probably 9.5V under load.

As for the model 2 adaptor, the same thing will be happening.

As far as running the 11.5V system on the 12V the short answer is: not likely. What it will do is cause a slightly increased temperature inside the case (and I mean an extra 10% of waste power being produced) and strain your PSU components a bit more but probably not worth enough to worry about.

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Re: Sega CDX Actual Output Voltage Amperage Output

Post by TSX420J » Sat Jun 16, 2012 9:39 pm

evilteddy wrote:Apparently not many people on these forums know much about the Sega CDX :P
In any case, in general many of these older regulators won't be switchmode and as such won't be regulated as you might be used to with modern adaptors. With that in mind its important to measure the voltage and current draw while the system is on. From you only showing the voltage of your power supply (at an elevated level) I assume you were just measuring the power supply while it was open circuit and not powering anything.

TLDR: measure power supplies when they have their load connected. Your '14.5V' supply is probably 9.5V under load.

As for the model 2 adaptor, the same thing will be happening.

As far as running the 11.5V system on the 12V the short answer is: not likely. What it will do is cause a slightly increased temperature inside the case (and I mean an extra 10% of waste power being produced) and strain your PSU components a bit more but probably not worth enough to worry about.
Thanks for the reply!! I tested the voltage under load and it reads 12.06v. Measuring the voltage not under load it reads 12.08v. So the voltage drop is minimal under load, when seeking in Sega CD mode. I don't know if an OEM adapter would stabilize at 9.5v under load. I do notice the bottom of the CDX gets a little warm after a half hour of use, but I think that is normal with all consoles. I think I might get a modern linear voltage regulator that is more robust to be sure this CDX won't burn up on me. I might even add a metal plate to the LVR to act as a heatsink to dissipate excess heat as well. Thanks again for your input, it is greatly appreciated! :) I will let everyone know how it goes.

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Re: Sega CDX Actual Output Voltage Amperage Output

Post by evilteddy » Sun Jun 17, 2012 1:38 am

Yeah, the reason the newer adaptor isn't changing voltage too much under different loads is likely because its switchmode. Anyway, should be good.

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