DM6802-II Standalone Temperature Meter (UPDATED WITH CAL)

[T4P]

Well i have been eyeing this temperature meter for a long time, why?
Sometimes i really had enough of a DMM's built in temperature measurement. Okay, they go for 20$ @ DX (http://dx.com/p/2-2-lcd-digital-thermometer-handheld-temperature-tester-1-x-9v-6f22-120770, http://dx.com/p/k-type-digital-industrial-thermometer-with-sensor-50-c-1300-c-7286) and i basically paid only 15$ but i'm fairly happy with this instrument for a few reasons,
1) I can quite trust it
2) The temperature probes supplied feels 1000x better than the ones you get with a 20-30$ DMM with temp
3) degrees C/F as well as kelvins measurement : handheld DMMs doesn't have that right? I don't like to do maths all the time
4) Max/Min/Avg, again, a average 50$ handheld DMM usually doesn't have Average!
5) Handy T1 minus T2 feature, i wasn't expecting that. I was expecting something like T1 and T2 on the same display
6) Office table test! It isn't as slippery as a used car salesman, in fact it doesn't even move at all but it doesn't have to
7) Twist test! It's good in this area
.1 degrees resolution all the way

Here's a few hate though :
Startup takes forever (5 secs i know is not slow but it's slow for a handheld device)
Plastic feels incredibly cheap
Flip up stand doesn't fall over but it feels like crap

The thing is, it is indeed terrible quality but i'll get to the main point okay?
IT'S A temperature meter. I don't really care for input protection on this meter because really which i wouldn't rent any of my meters to any idiots. Not even a agilent if i had one
I don't really have much else to say but i found flux residues all over the the input terminals and some white flux residue the jumpers, water soluble flux i guess?
Odd i know but the flux residue on the terminals are really RMA.


The back of the board is so boring ... it's only single sided

What's the result of a incredible cheapy? Don't buy it. If you bought it then sorry about that.
After a month or so of usage i went to my good friend's cal lab and discovered i have been led-on again!
To confirm my results that his lab really isn't at 28C i stuffed the probe into his 10C thermal chamber to find that it was indeed reading 5C higher, on T1
On T2 it was even worse, wafting to 10C above actual temp (And i ain't even using proper K probes he had, it just gives jibberish results on the DM6802-II, so i resorted to just using standard supplied TP01 probes)

As a result? Cheapies thermometer = crap. Buy a UNI-T for heaven's sake
Build quality is crap on this one and you can't trust it either because it's badly out of spec

[grenert]

That thermometer is designed to look like the ancient Fluke 52.

[T4P]

I'll bet the people who designed that looked at the fluke 52 and thought "Why not?" 

[amyk]

I don't think input protection is that important here either, it's not a DMM and all you should be putting in the sockets are thermocouples anyway. Not surprising the main chip is a COB, probably 4-bit micro running at a few tens of kHz.

Do the buttons match the text on the case or the PCB silkscreen?

[T4P]

Exactly, that was my point 
The buttons do not match the silkcreen     

[peter.mitchell]

That's good because if they matched the pcb silkscreen I'd be awecul curious what the FCK1 button does.

[T4P]

Updated with cal lab findings

[fpliuzzi]

Hello,
I have the same digital thermometer, with a different name printed on it. My device has calibration info in its "manual". Here is the exact wording in the manual...

------------------------------------------------------------------------------------------

USER SELF-CALIBRATION

  EXPLAIN: HOLD button denote data up (+)
                 T1/T2 button denote data down (-)
                 T1-T2 button denote ENTER

                 LCD display T1 indicate low-temperature
                 LCD display T2 indicate high-temperature

A. The thermometer is shutdown,  Press"°C/°F/°K & POWER", the LCD display "USE2 T1 °C " symbol. Press "T1-T2" button enter the next step.

B. The LCD display "T1". The signal source's reading turn to 0°C, press "HOLD" for "+", press "T1/T2" for "-". When the thermometer's reading is the same as the signal source's reading Press "T1-T2" button enter the next step.

C. The LCD display "T2". The signal source's reading turn to 100°C, press "HOLD" for "+", press "T1/T2" for "-". When the thermometer's reading is the same as the signal source's reading press "T1-T2" button, at this time the LCD will be FULL flash and turn on the thermometer. User self-calibration is finished.

RESUME FACTORY SETTINGS

In the shutdown mode, press "POWER" & "T1-T2" buttons.

------------------------------------------------------------------------------------------

I hope this makes sense. I see that some people only received instructions in Chinese with their units, so the above info may help them out.

Regards,
Frank

[T4P]

You recieved instructions? Great. Because i recieved none 
I had two probes and 1 broke and if i used another one i have from my friend's cal lab it goes out of whack very badly (And cal procedure goes on again ...  )

[mzzj]

You recieved instructions? Great. Because i recieved none 
I had two probes and 1 broke and if i used another one i have from my friend's cal lab it goes out of whack very badly (And cal procedure goes on again ...  )

Found this thread by accident after ordering one from ebay. Just got it from postal guy.
Okay, here is my experiences:

did a full calibration for the meter and its pretty much spot on!
For most of the range error is <0,5K and never exceeds 1K.
Excellent result considering that this is for K-type thermocouple.

Yes, the meter feels really cheap, mostly because it weights next to nothing. Adding big chunk of steel inside and it would feel just fine 

I haven't calibrated the probes yet, but I expect that they are utter crap. Not a problem since i have 100m spool of good quality thermocouple wire 

http://www.ebay.co.uk/itm/DUAL-TWO-CHANNEL-2-K-TYPE-DIGITAL-THERMOMETER-THERMOCOUPLE-SENSOR-1300-C-/301223741482
for the price I am more than satisfied