Need buyer's advice: Uni-T UT70B

[Mr Eastwood]

Why they are still bundling COM port cables for logging etc is beyond me! do they know it's nearly 2013 not 1993! ;-)

The IC in those USB/COM adapters it is protected by patents, and holds special programing which is included in the software drivers of its manufacturer.
This IC has an specific cost, which some one has to pay.
Just a COM port cable in our days translates that the manufacturer are cutting corners in the wrong way.

Surely it wouldn't hurt them to add Bluetooth;  being able to remote operate / log and calibrate etc without cables makes much more sense and it's a great selling feature!

[iloveelectronics]

This is just your own estimation, every serious seller on Ebay offers one warranty plan.

Hmm...I've had a quick look through eBay but can't find any UT61E seller offering warranty. They do offer return and refund on buyer's expense though. Honestly if any of them do provide warranty they are probably just counting on the fact that shipping (to and from China) would cost too much for the buyer to bother. The units can certainly be sent back to China for repairs where the warranty is valid, but I really doubt anyone would pay all the shipping expenses (and wait forever) to do that. You can almost buy a new unit with all the shipping fees.

[Kiriakos GR]

Blue-tooth is another protected by patents technology.

The point is that UNI-T has an target to become top seller in China which is a different and less demanding market.
Europe and USA which both has more advanced technology they need the absolutely best.   

[Kiriakos GR]

@iloveelectronics you did convinced me to not buy anything from the eBay sellers of China.
With just 15% more at the retail pricing from the local retailers, based on your words,  it makes more sense to buy locally and be 100% protected as consumer.

[iloveelectronics]

@iloveelectronics you did convinced me to not buy anything from the eBay sellers of China.
With just 15% more at the retail pricing from the local retailers, based on your words,  it makes more sense to buy locally and be 100% protected as consumer.

Of course, it's great to have a choice between warranty and cheaper price, and if the difference is only 15% it certainly makes sense. People in some countries may not be so fortunate to have the options though. Their local stores may not carry The Uni-T brand or this particular model, so if they still want it they may have to go to places like eBay.

[retiredcaps]

They do offer return and refund on buyer's expense though. Honestly if any of them do provide warranty they are probably just counting on the fact that shipping (to and from China) would cost too much for the buyer to bother. The units can certainly be sent back to China for repairs where the warranty is valid, but I really doubt anyone would pay all the shipping expenses (and wait forever) to do that. You can almost buy a new unit with all the shipping fees.

I couldn't have worded any better that what Frankie wrote.  I have been burned before on ebay despite my best due diligence.  The high shipping return costs negates my motiviation for sending the item back.

Now if Frankie were to open up all the units he receives from a supplier and tested all functions, then I would have confidence and pay more for that service.  The tests don't have to be exhaustive, but it would rule out a lot of DOAs or catch a lot of simple things.

[iloveelectronics]

I couldn't have worded any better that what Frankie wrote.  I have been burned before on ebay despite my best due diligence.  The high shipping return costs negates my motiviation for sending the item back.

Now if Frankie were to open up all the units he receives from a supplier and tested all functions, then I would have confidence and pay more for that service.  The tests don't have to be exhaustive, but it would rule out a lot of DOAs or catch a lot of simple things.

While I don't really "test" all the units I do try to turn them on to see if they at the very least switch on and that the range switch is turning ok, etc. I do that because I have to take the battery out of every one of them as the post office told me specifically that batteries are not allowed in these parcels. Since I have to open each unit up anyway I thought I would do this simple test. I would have no problem running a few more simple tests if the customer so tells me. I don't have much volume to deal with at this stage anyway so it's not a big deal for me

I can't speak for other eBay sellers but for me I only put up items that I have personally used or tested for sale (not the used items, but new ones ordered after passing my own quality examination). I have bought a lot of other Chinese junk which I figured are simply, junk, and I would not sell them. I'm basically doing the same with the Mastech multimeters that I posted in another thread. I'm paying a lot of money out of my own pocket just to see if they are even good enough to be sold.

English is not my native language but I believe I have a decent command of the language to communicate well with my buyers too, which is also another thing I try to differentiate myself from other Chinese/HK eBay sellers.

My apologies if this has turned too much into a self advertising post... Martin, feel free to edit or delete as you see fit.

[Kiriakos GR]

Their local stores may not carry The Uni-T brand or this particular model, so if they still want it they may have to go to places like eBay.

Today which one shipment of EMS needs only six days to be delivered from China to Europe,  translates to zero delay of getting here the latest.
By having 276 transaction on eBay as buyer, I can say that the smart buying decisions it is up to the education of the buyer.
Naturally the eBay protection system it does work even slowly.

Last year I got an New & fast VGA card for my PC from eBay Germany.
Not happy with the product in a week?  Free Shipping back / Communicate with us for the arrangement and refund / no other questions.
Warranty 2 years ...  Free Shipping back / Communicate with us for the arrangement. 
 
Yes the local dealers they have form an more competitive sales network, which is hard to compete.
My advice as friend will be to offer one year signed warranty, if you are not an occasional seller.   

[th69xx]

UT70B - wrong values in 40mA range

Hello together,

am using the UT70B (UNI-T) since year 2004 - and the device satisfies my needs, so I could recommend it in general. I am using it for hobby and as well for professional purposes.

After a few years using time I noticed wrong values in the 40mA (DC) range. The exact behaviour is as following (see also the photos in the attachment - UT70B on the left side, on the right side is a multimeter for comparing):

While measuring "real" currents between 0mA and 20mA the device shows a value which is approximately twice as high as the real current (photo: 15mA-not-OK). Pressing the range button in this situation in order to switch to the 400mA range leads to a correct value display (photo: 15mA-OK). The auto-range function selects the range with the highest possible resolution, so that wrong values are always displayed in this situation, as far as the range is not changed manually.

If the measuring current is between 20mA and 40mA, the auto-range function does not find the correct setting (photo: 20-40mA_AutorangeEndlos). It seems that the device is detecting a range overflow due to the incorrect "doubling" of the display-value, but it does not switch to the next measuring range. Also in this case the correct display value can be seen by manually selecting the 400mA range (photo: 20-40mA-OK). With the ľA and A ranges I did not notice similar problems (the 40mA AC range I did not check yet).

This case of problem seems like a "design-problem" to me that does not only occur with my UT70B example - I do not remember "special events" in my using period that could have destroyed the 40mA range. Maybe the problem did exist from the beginning and can also be shown with other examples.

So my question is if anyone of you UT70B owners could take the time and do some tests and reply if my problems can be confirmed / not confirmed.


Thanks in advance,
Thomas

[Mr Eastwood]

Hi,  i've just checked mine and it seems ok (see attached)

[Mr Eastwood]

Maybe if the 400mA range is reading fine then we could assume the front-end is ok;  but if the 40mA range is not quite right I would have thought the problem might well be the chipset; as that would be responsible for the auto-ranging / attenuation etc.

Have you blown many mA fuses in the past?   have you always replaced used the correctly rated / type fuses?


[edit: I'd be interested to see what the 400μA/4000μA ranges measure. ]

[th69xx]

Thanks for checking and your quick answer!

This is proof enough for me that it is no design problem.

Your questions:
Have you blown many mA fuses in the past? => no;   have you always replaced used the correctly rated / type fuses? => not relevant;

For the fuses, I checked just now where they are mounted and I am quite sure that I never had this type of fuses in my hands (white ceramic instead of well known glass tubes) - so I am sure I did not have to replace them.

See the attached picture: There are two overheated resistors besides the 10A fuse - this is very likely my problem. I will report the result when I have repaired this. Could you take some time again and determine the correct values of the resistors for me? The colour code is no more visible at my device.

I should have done this quick check inside the device before writing the test report - would have been easier, but as I did not blow any fuses, I did not think about damaged parts...

[Mr Eastwood]

Attached is a schematic for the UT70b; which should help you identify any parts.

[edit]
I'll try and get a picture as well for you after work tonight;  but you certainly burned the pants off those little suckers! ;-)

[Mr Eastwood]

Attached is a picture of my DMM and the resistors for you;  I use a 500mA glass fast blow for the mA range on mine but only because I don't have any 800mA ones in my box.

[th69xx]

Thank you very much so far!

This is enough information to change the resistors (little suckers - you called them...).

Have a nice time,
Thomas