quest
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Scale don't work
Hi all,
I got a "E4000D OHAUS scale". I have had it for over 10 years.
Today the scale decided not to work for the first time.
I tried to find out what was wrong, I have connected the power supply to the power and used a voltmeter to see if the wires are cut or the transformer
is broken - I couldn't find 2 wires that have 17volts between them. (actually I couldn't find 2 wires with any voltage between them)
And now for my questions:
1) Is there any component in scales that is prone to "die" first? How can I check if it is broken?
2) Does any one know why the scale power supply has 3 electric wires coming out of it and not only 2? (1 positive and 1 negative)
3) If I can't find 2 wires with some voltage between them - does it mean the wires are broken\the transformer is broken like I guessed?
thanks.
 
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not_important
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Third wire is ground - 0 V If you can't find any voltages out of it, it is dead. Note that it's more than a transformer, it's also rectifiers to
get the DC.
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m1tanker78
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Also keep in mind that this PS supplies a dual rail +17V | 0V | -17V. Your meter should register +/-34V between the rails and +/- 17V from either rail
to the common ground. Are you able to disassemble the PS?
If it really is transformer-based, as opposed to a switching type, then it should be fairly robust. If it's a buck converter (for example), it's
almost certainly trash or junk box bound IMO.
Also note that the manufacturer, EDS, disbanded a few years back. Try contacting Ohaus to see if they can offer any help for a replacement PS or check
ebay.
Tank
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weldit
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This may sound stupid but did you check the outlet. If your outlet has power get another power supply
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quest
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A new PS costs 130$ from the authorized ohaus dealer.
Do you know if it has special part to make it more accurate or this is just a too expensive price?
Can I make a PS with +-17 volt or will it make the scale less accurate because it doesn't have thermal voltage regulator to make the voltage more
consistent? (again, I don't know if mine has it, it's just a guess because of the price.)
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redox
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I asked my uncle (who is a self-made millionaire in the scale business ), and
he said it is often the load cells that fail first. Are there electronic-fixing stores near you? Contacting Ohaus may also yield results.
If all else fails, it seems buying another scale would be necessary.
Also, this may be a noob question, but what is a PS?
My quite small but growing Youtube Channel: http://www.youtube.com/user/RealChemLabs
Newest video: Synthesis of Chloroform
The difference between chemists and chemical engineers: Chemists use test tubes, chemical engineers use buckets. |
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#maverick#
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when he says PS i believe he is referring to the power supply now i may be wrong
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redox
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Thanks Mav, that makes sense.
My quite small but growing Youtube Channel: http://www.youtube.com/user/RealChemLabs
Newest video: Synthesis of Chloroform
The difference between chemists and chemical engineers: Chemists use test tubes, chemical engineers use buckets. |
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m1tanker78
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PS[U] = power supply [unit].
If the scale performs an auto-zero when it's powered up (don't see a discrete button) then you could probably get away with using a more crude
solution for the power supply. Or, you could just 'tare' the unloaded scale as needed. If you have a handle on basic electronics, your best starting
point would probably be a 24V center-tapped transformer. These are almost annoyingly abundant in a typical electronics junk box.
Another option is looking for a split rail integrated circuit and working up from there. You'd be surprised at the availability of circuits-on-chip
nowadays.
Personally, I'd buy a cheapie Chinese scale and make it work while getting around to repairing or replacing the faulty PS. If you're certain that the
PS is dead then tear that son of a bitch apart. You have nothing to lose and may even find the problem and be able to repair it.
Just sayin'
Tank
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