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Is There a Switch? One Multimeter and 10 Units Under Test

05/13/2011 6:25 PM

There is a STB power Supply no-automatic test which has just 7 second warming time.

I have been asked to change the 7 second warming time to 5 minutes burning time before to perform volt-amp measurement.

I am thinking to use a 5491B true rms bench multimeter from B&K for volt and current measurement which is very expensive compared to the actual equipment (somewhere home made).

In this case I would like to set up a semiautomatic test in which operator will be able to test more than one STB power supply in order to compensate the 4:53 minutes difference.

I think in a commercial switch available somewhere, which I still do not know, which allow me to use a micro controller or a PC to make the switching from one power supply to another. I would like not to loose time designing one.

Somebody would like to recommend to me one.

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#1

Re: Is there a switch?...One Multimeter and 10 units under test.

05/13/2011 8:27 PM

What does STB mean, and what are the specs on the power supply?

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#2

Re: Is there a switch?...One Multimeter and 10 units under test.

05/13/2011 8:30 PM

I am sure a suitable switch can be found, but more information is needed. (And, in fact, a manually operated switch is probably all you need.)

To start, what is the voltage level you need to measure? And what is the current level? (I'm assuming you need to do both because you say volt-amp measurement.)

If you are measuring amps, you will need some kind of test load. Is that test load connected to the STB power supply throughout the 5 minute burn-in, or is it only switched in when needed to do the amp test?

I think you need to make a schematic diagram of how things are connected when you test one power supply, and then consider how you'd modify that to burn-in ten at a time, and how you and where you'd switch in the meter to get a voltage and current reading for each of those 10.

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#3

Re: Is There a Switch? One Multimeter and 10 Units Under Test

05/15/2011 4:51 AM

For me the simplest solution to your problem would be to use a bunch of appropriately rated 4 pole relays (one for each of the power supplies being tested) and a selector switch that had as least as many positions (plus one if you want an OFF selection) as power supplies you want to test.

The components shouldn't be too difficult to source and given the parts, a soldering iron, roll off hook-up wire and a day or so and bingo you have a selector box.

It should be simple enough to do in your head without even drawing a circuit diagram but given that somebody else is likely to have to work on it at some time in the future the extra hour or so it would take to draw up a circuit diagram would be worth it.

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#4
In reply to #1

Re: Is there a switch?...One Multimeter and 10 units under test.

05/15/2011 8:09 AM

I'm guessing Set Top Box, but, it could be standby.

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#5

Re: Is There a Switch? One Multimeter and 10 Units Under Test

05/15/2011 8:16 AM

If you use resistive loads (i.e. big resistors) you only need to monitor that the voltage output is within spec.. I'm sure you could find something much cheaper than a B & K instrument.

Also if you are only measuring the voltage then you don't need to switch big loads and any test switching array or set of relays will do.

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#6

Re: Is There a Switch? One Multimeter and 10 Units Under Test

05/15/2011 9:36 AM

"to perform volt-amp measurement".

To do voltage measurements safely, the multi-meter has to be set on volts mode and its proper voltage range!

To enable you to measure Amps, is a bit different since you need to cut open one of the main power lines to put your meter in-between (series), and the ammeter set in its proper safe range to avoid destroying your meter!

Worry about the automatic operation process later on after you familiarize with the above!

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#7
In reply to #1

Re: Is there a switch?...One Multimeter and 10 units under test.

05/16/2011 11:18 AM

STB = Set Top Box

12V, 2.5 Amp STB Power Supply

12V, 1.6 Amp STB Power Supply

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#8
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Re: Is There a Switch? One Multimeter and 10 Units Under Test

05/16/2011 11:41 AM

Topic is about a switch not about multimeter. I will appreciate if you can recommend to me a better multimeter for listed characteristics.

Voltmeter must be controlled by a MC or a PC.

AC voltmeter (to measure the input voltage parallel to STB Power Supply)

> 1 M input impedance

measurement error most 0.10 V in the voltage range used in this test.

DC voltmeter (measured at the load)

> 10 M input impedance, and

measurement error at most 0.01 V in the voltage range used in this test.

Voltmeter MUST refresh its voltage measurement at least every 500ms. (It MAY refresh more frequently.)

Thank you!

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#9
In reply to #6

Re: Is There a Switch? One Multimeter and 10 Units Under Test

05/16/2011 11:47 AM

This topic is about a Switch not about:

1. Voltmeter needed

2. How to perform a Volt and amp measurement

3. Not about Automatic Operation Process.

Ones I have a doubt about it I let you know.

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#10

Re: Is There a Switch? One Multimeter and 10 Units Under Test

05/16/2011 11:52 AM

I appreciate your inputs.

Reading what yo have posted I will go for a home made switch.

Best regards!

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#11
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Re: Is There a Switch? One Multimeter and 10 Units Under Test

05/16/2011 12:28 PM

Pickering make a huge range of switching matrices for test purposes:-

http://www.pickeringtest.com/

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#12
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Re: Is There a Switch? One Multimeter and 10 Units Under Test

05/16/2011 1:45 PM

Thank you Randall:

This is what i was talking about!!

http://www.pickeringtest.com/products/2143.html

I am curious if my boss will approve it :).

I am preparing my self to make one.

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#13
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Re: Is There a Switch? One Multimeter and 10 Units Under Test

05/16/2011 6:04 PM

How can one expect to come up with a functional switching mechanism that will enable the measurements to be accomplished properly and safely if the difference between the two parameters and how they are measured are not known???

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