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.
not_important - 8-8-2011 at 07:20
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. m1tanker78 - 8-8-2011 at 07:58
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.
Tankweldit - 8-8-2011 at 13:46
This may sound stupid but did you check the outlet. If your outlet has power get another power supplyquest - 10-8-2011 at 14:39
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.)redox - 10-8-2011 at 15:57
1) Is there any component in scales that is prone to "die" first?
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?#maverick# - 10-8-2011 at 18:08
when he says PS i believe he is referring to the power supply now i may be wrong redox - 11-8-2011 at 04:23
when he says PS i believe he is referring to the power supply now i may be wrong
Thanks Mav, that makes sense.m1tanker78 - 13-8-2011 at 06:39
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.
), 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. 