2014-01-18

DT9205A multimeter review

DT9205A is extremely cheap digital multimeter. I've bought it for ~$7 plus shipping.
Specification looks fine. Few pages of instruction is shared with DT9201A, DT9202A, DT9203A, DT9204A, DT9206A, DT9207A and DT9206A. These other models differ mostly in function set selection, i.e. they offer frequency or temperature measurement in place of one of the 200MOhm resistance range. DT9203A and DT9204A have 4.5 digit reading and better nominal accuracy.



 Included probes are short (~60cm), made from cheap plastic (well, like anything else here) and very susceptible to damage - it feels like cable may tear out of plastic end at any moment.
Multimeter is based on ICL7106 chip (or its clone?). Two other ICs visible here are LM324. When looking at other dissasembly pictures on the internet it's clearly visible that actual PCB design varies greatly between particular multimeters marked as DT9205A. In particular many of them are built mostly with THT components placed on opposite side of the PCB. Schematic for those is easy to find and seems more or less matching this one - main difference is using 4 dual instead of 2 quad operational amplifiers.
Built quality and input protection is in pair with price.
 The lost art of using wire cutters:
 Input protection (MOV?) is almost touching transistor tester socket wires.
 Badly positioned LM324.
 Trace to nowhere (I doubt if this could be some kind of overvoltage protection; also I've already cut socket pins that were touching MOV here):
On a plus side: continuity tester has optical (LED) + acoustical signalization and indication works without any delay. Don't forget the price too.
Problems spotted:
  • diode forward voltage measurement is highly inaccurate, i.e. it shows ~800mV forward voltage for red LED diode