Speery (Uni-T) DM6600 Multimeter teardown.   - Page 1
Forum section: electronics / testgear

author: Robomeds
author_rank: Frequent Contributor
timestamp: July 06, 2013, 05:16:59 pm
content: This is a low cost meter that I got a while back. I think it was $35 new on Ebay (it is today). I don’t think it would surprise anyone to hear this is clearly a Uni-T design. However, unlike the Craftsman-Extechs, I can’t find a corresponding Uni-T model.The probes are the same as the UniT probes. Better than some cheap ones but not Fluke or Agilent.The overall build quality is good. It feels solid and doesn’t slide around on the bench. The tilting stand is rather weak feeling. The meter leans back further than I would like as well. Then again, it is stable. The knob feels good as do the buttons. The backlight isn’t even but it is bright enough. I don’t like having to hold the button down to activate it. The non-contact voltage detection is only active if you hold the button down during power on. Fail there. The input sockets are a mixed bag. The voltage and common have little resistance and feel loose. The current sockets are solid. Looking inside explains why.I suspect all the build quality comments that apply to the Uni-T UT71 series apply here.The large screen is easy to read except that the curved face picks up glare quite readily. The control knob moves nicely. The power switch is a toggle which I’m not overly fond of. There is no auto power off. Instead the meter starts to scream at you after 30 minutes. It works I guess. There is an optical out port on the back but the meter doesn’t support the function. I suspect the chip does but the parts aren’t populated.In use the auto range is annoyingly slow. In fact this is the meter that got me to think about auto range speed. My first auto range meter was my RS pocket meter which topped out at 2Mohm so auto range wasn’t a big deal with only a few ranges. Slow is also a good description of the latched continuity check.The Hold is only for the instant screen data. The min/max doesn’t have average like the Flukes. I typically like the bar graph but only when they are done right. Correctly done means the graph updates quickly. Many meters have graphs that update as say 4,5 or even 10x the digits. This one does not. The graph and digits update at the same time just like the cheap VC99. Basically on paper this meter looks better than it proved to be in practice.So on to the guts.The back is held on by 4 self tapping screws. One is in the center and one small one at the RS-232 port. Two are under the bottom feet.Inside we find the reason why some input jacks feel so solid. The current jacks are the split type that could, if wired as such, detect incorrectly inserted probes. The common and voltage jacks are the cheap rolled kind. I didn’t see any clearance routing but the traces seem to have a lot of space on the PCB. The fuses are British BS1362s. Not the best but certainly better than glass things. The voltage protection looks like a single PTC. I found two instances of bodged components, C16 and C25.All around I would say it’s a cleaner layout vs the Ideal I presented the other day. Functionally it’s not as nice. It does have the NCV detection but the slow auto range and continuity are annoying.I didn’t specifically check for accuracy but in the past this one seems to have agreed with my Flukes, at least agreed enough to likely be in spec. I wouldn’t go out of my way to get one of these but I wouldn’t fear using it either. Of course having used a Fluke meter I really am spoiled. They work so well. If only an 87 cost x2 the price of one of these cheap meters instead of 10x. Anyway, if you see one cheap and need a beater meter you could do worse.Ringing endorsement that.

author: Lightages
author_rank: Unknown
timestamp: July 06, 2013, 06:59:25 pm
content: It looks like a $35 meter, no more. After buying my Uni-T UT71E, I immediately started out on a journey to find mutimeters that actually are safely built, work well, and don't cost the same as the Flukes.Thanks for the review.

author: Hydrawerk
author_rank: Super Contributor
timestamp: July 06, 2013, 08:30:12 pm
content: Well, the fuses are quite easy accessible. Much better than on my UT70A. But the fuses should be larger.

author: retiredcaps
author_rank: Super Contributor
timestamp: July 07, 2013, 06:03:29 am
content: @Robomeds, thanks for another review and teardown. Keep them coming!I had the same multimeter around the April 2012 timeframe. Your review covers what I found too with this meter.Here is the only internal picture that I took when I had it.

author: retiredcaps
author_rank: Super Contributor
timestamp: July 07, 2013, 06:08:26 am
content: When I looked at a new once last year, pricing was around $100 MSRP. Places like Amazon, Galco, Tequipment still list it around the $100 mark. Luckily I got mine at Robomeds "like" prices on his/her Ideal/Fluke 8025B.

author: Wytnucls
author_rank: Super Contributor
timestamp: July 09, 2013, 08:31:07 am
content: There is no corresponding DMM amongst the UNI-T line-up, as this was a meter put together for a Sperry contract, according to their modest specifications.Sperry probably liked the 71 series shell, as it gave their basic meter an expensive look.It looks like the PCB has the RS232 circuitry in place. It should be easy to populate the missing parts with an IR diode and a matching current limiting resistor, for data logging.

author: Robomeds
author_rank: Frequent Contributor
timestamp: July 10, 2013, 02:31:46 am
content: I had noticed the unpopulated parts. I didn't think about just adding them. I wonder if I have to add a button to activate the RS232 out or if it would work like some of the other UniT models that just constantly stream. Not that I need that ability as I have another meter that can log... and I can't think of the last time I needed real logging vs just min, max, ave.

author: Wytnucls
author_rank: Super Contributor
timestamp: July 10, 2013, 04:14:48 am
content: RS232 should be activated by a long press on the REL button, according to the markings on the PCB.