SNS-002: How do I test the output?

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crix0r
Posts: 4
Joined: Wed Jun 03, 2020 12:01 pm
Location: Virginia

SNS-002: How do I test the output?

Post by crix0r » Mon Jun 22, 2020 11:00 am

Hello Everyone -

I recently came into a handful of SNES power supplies, model SNS-002, and I would like to be able to test them somehow to ensure that they are good to go before I plug them into something and find out the hard way that something is wrong.

So, I've got a multimeter and I'm curious:
  • How should I test these? I assume I'll plug the SNS-002 into the wall, put my meter into DC mode... but after that I'm not certain which color lead goes to the inside or the outside of the barrel connector, etc.
  • What output should I be seeing when they aren't under load? I realize that the SNS-002 will probably have a higher output if I plug it into the wall and test from there (as opposed to plugging it into a SNES and test the SNES side to see what I get), but I don't know what the expect values are.
Thanks!

crix0r

lidnariq
Posts: 9779
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Location: Seattle

Re: SNS-002: How do I test the output?

Post by lidnariq » Mon Jun 22, 2020 12:07 pm

Unfortunately, I broke my SNS-002 a couple years ago, so I can't tell you any specific measurements. But it's a very simple design: a transformer with a center-tapped output and two half-wave rectifiers, going into a 16V 4700µF filter capacitor, and a 3.3MΩ coupling resistor to loosely couple the negative (center) to wall neutral.

Without opening them, all should have roughly the same resistance across the two mains pins, and you should be able to measure/detect the 4700µF capacitor from barrel connector.

I don't know what kind of no-load voltage you should expect to see, but since the filter capacitor is rated 16V, it should be less than 16V. You could make a test load out of a bunch of ordinary resistors to see if you can get a stable 10Vdc and 850mA into a 12Ω, 8.5W load.

crix0r
Posts: 4
Joined: Wed Jun 03, 2020 12:01 pm
Location: Virginia

Re: SNS-002: How do I test the output?

Post by crix0r » Tue Jun 23, 2020 3:51 am

lidnariq wrote:
Mon Jun 22, 2020 12:07 pm
Unfortunately, I broke my SNS-002 a couple years ago, so I can't tell you any specific measurements. But it's a very simple design: a transformer with a center-tapped output and two half-wave rectifiers, going into a 16V 4700µF filter capacitor, and a 3.3MΩ coupling resistor to loosely couple the negative (center) to wall neutral.

Without opening them, all should have roughly the same resistance across the two mains pins, and you should be able to measure/detect the 4700µF capacitor from barrel connector.

I don't know what kind of no-load voltage you should expect to see, but since the filter capacitor is rated 16V, it should be less than 16V. You could make a test load out of a bunch of ordinary resistors to see if you can get a stable 10Vdc and 850mA into a 12Ω, 8.5W load.

Thanks! I'm intrigued by your load out test jig idea. I'm going to see what I can whip together.

crix0r

Jagasian
Posts: 421
Joined: Wed Feb 09, 2005 9:31 am

Re: SNS-002: How do I test the output?

Post by Jagasian » Wed Jun 24, 2020 8:58 pm

You really should use an oscilloscope to test because you need to see what the voltage ripple and noise looks like. I recently replaced the capacitor in my SNES power supply with an ultra long life 135 Celsius rates cap. Here is what my oscilloscope shows when there is no load and then with load.
No load is around 14 volts output
No load is around 14 volts output
With load the voltage is around 10 volts out
With load the voltage is around 10 volts out

lidnariq
Posts: 9779
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: SNS-002: How do I test the output?

Post by lidnariq » Wed Jun 24, 2020 9:02 pm

For this specific and narrow instance, just measuring Vrms and Vdc with the test load connected would be ok. An oscilloscope will give much better confidence, but if you don't have one don't worry about it too much.

crix0r
Posts: 4
Joined: Wed Jun 03, 2020 12:01 pm
Location: Virginia

Re: SNS-002: How do I test the output?

Post by crix0r » Thu Jul 30, 2020 5:37 am

Ahhh, interesting Jagasian, and thank you!

I don't yet have a scope, but I plan on snagging one here shortly. It seems that trouble shooting without one is far more frustrating that with one. Any recommendations for a good cheap one? Most of my testing/tinkering will be on NES/SNES/N64, if that matters.

crix0r

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