Westward RMS Multimeter (APPA Isotech 105R) teardown - Page 1
Forum section: electronics / testgear

author: Robomeds
author_rank: Frequent Contributor
timestamp: August 28, 2015, 11:34:53 pm
content: I’ve had this meter sitting around for a while just waiting for a tear down. I suspect most here haven’t heard of the Westward brand. They are a house brand of the industrial supply company Grainger. In that regard they are a bit like Craftsman and other Sears brands in the US except that Craftsman at least seems to have stuff custom designed for them from time to time. Looking at features etc this meter appears to be identical to the APPA 105R save for the colors and the lack of a the agency listings seen on the front of the APPA version:http://www.drihm.com/fotos_productos2/appa-105r.jpgThis review will also look quite similar to this older one for a similar meter:https://www.eevblog.com/forum/testgear/iso-tech-%28appa%29-idm105-dmm/15/The short version is the meter is a 4000 count, 0.1%+2D DCV, TRMS meter. Its claims to be rugged and water resistant and I suspect it would live up to both claims reasonable well. It has a 600V CAT3, 1000V CAT2 rating. The meter also was clearly from the days of Fluke 87 envy. Front and back, it would be hard to look more like an 87 and not get a letter from Fluke’s legal team.Anyway, the meter is actually quite solid. It basically feels as solid as an 87. The screen has great contrast and is very easy to read. In that regard it’s far better than my 87-V and the 11x series Flukes I’ve used. Probably better than the 87-III I used to have. Really, beating the 87-V isn’t that impressive. Having had an 87-3 the 87-5’s contrast was a disappointment. So big win on the display… but no backlight. The knob feels basically the same as my Brymen meters (Greenlee DM-200A, Amprobe AM-270 at work). Decent enough but a bit too much like plastic is breaking each time you turn it, not as good as the Flukes I’ve used.In testing I found that it was reading a bit higher than my 87-5 but, assuming my Fluke is spot on, it would still be in spec. Auto ranging is quick but the continuity tester is about the same as my Greenlee (Brymen 257 based) meter. Not slow but not fast. It is latched.The case/boot is good but doesn’t quite feel as good as the Fluke. When you look at the back panel it just screams 87-1. We have the button-function list at the top, and three screws to hold the whole works together. However, in the area it beats the 87. The screws go into inserts and have gaskets under the heads. The case opens easily when the screws are removed. The halves have a nice overlap with a gasket in the bottom. There are also O-rings where the probe connectors go thought the front of the case. It doesn’t look like it could handle immersion but certainly a good splashing is going to be kept out.On to the inside:The jacks are clamped to the board with screws. That seems an improvement over the APPA in the above link. No isolation slots but the meter is only a 600V CAT3 so that’s probably fine. The solder joints look decent enough. Not the near perfect stuff Fluke makes but respectable. All you see is the backside when you open it but the guts pull right out without even removing a screw.The control switch rotor is actually pinched between two PCBs and has contacts on both sides. I like how they mark it so you can get it in the off position before closing things up. Near the button contacts we can see 105-4E. I’m guessing that is APPA 105.The safety related parts all look totally up to the job. Proper fuses, 3 spark gaps, insulated input resistors and two PTCs and 5 or six input diodes. Then again, versions of this meter appear to be agency rated so I think this is stuff you would expect to see.The adjustments are all manual pots and one trim cap near the resistor network. They appear to be serious about the voltage divider. It’s a thin film model. I believe the voltage reference is an Analog Devices part under the top board. The main IC is a JRC part.Overall this meter somewhat reminds me of the older Brymen stuff. Not as good as Brymen but with in the rated specs it looks well made. It might not seem any better than some of the lower cost stuff out there but I suspect this one would handle industrial/automotive work just fine. I would be almost as happy using this as a Fluke 87-1. It’s not far off my current price favorite, the Amprobe AM-270 (Brymen based). Honestly, one of the biggest flaws is the coloring. The blue icons on medium gray is actually really hard to read even with good light. If you find one of these for not much money (I think this one cost me less than $40 in near new condition) it would be a great meter. Save for lacking a temp range it could be my primary meter… if I weren’t a tool monger.

author: Robomeds
author_rank: Frequent Contributor
timestamp: August 28, 2015, 11:37:24 pm
content: More pictures

author: Lightages
author_rank: Unknown
timestamp: August 29, 2015, 01:12:01 am
content: That actually looks like nicely built meter. It also looks like a late 90s design. How well does it perform?

author: Wytnucls
author_rank: Super Contributor
timestamp: August 29, 2015, 01:29:50 am
content: JRC multimeter IC:http://www.datasheet.hk/view_online.php?id=1088006&file=0028\nju9210_228933.pdf

author: Robomeds
author_rank: Frequent Contributor
timestamp: August 29, 2015, 02:03:35 am
content: Quote from: Lightages on August 29, 2015, 01:12:01 amI haven't messed with it that much. I bought it then right afterwards found a great deal on a Fluke 87-5. Guess which one I use...Anyway, the few times I've used it the thing works nicely enough. Like I said I hate the very poor contrast of some of the markings on the face but the LCD is very easy to read. The yellow Ideal meters have much easier to read color selections. I think it updates 2 times per second and the bar graph about 10x as fast. The leads are OK. Kind of what you expect out of $50-70 meters. Still, I would have no qualms about trusting it to deliver what it claims. I don't think as much of APPA as Brymen but this is a meter I would be happy to trust and, aside from the missing back light, it would probably be a great tool box meter. I would take it over the old boxy Fluke 23/77 type meters. I also wouldn't question someone if it was used on a bench somewhere.BTW, it took me a long time to figure out what the ADP input was for. The manual just said it was ADP mode. Thanks for nothing. Anyone want to hazard a guess?

author: retiredcaps
author_rank: Super Contributor
timestamp: August 29, 2015, 02:19:08 am
content: Quote from: Robomeds on August 29, 2015, 02:03:35 amADP = adaptor data plug-in?ADP mode for optional plug-in adaptors for temperature, for AC/DC current, for capacitance and for transistor hFE/loss measurements?

author: Robomeds
author_rank: Frequent Contributor
timestamp: August 29, 2015, 03:10:33 am
content: Quote from: retiredcaps on August 29, 2015, 02:19:08 amThat was it! It was supposed to be used with the amp clamp. In that mode 1mv in equals 1 count on the screen. I guess you could use the voltage range but they included this cryptic input. In fairness, it probably wasn't cryptic in the other owners manuals.

author: retiredcaps
author_rank: Super Contributor
timestamp: August 29, 2015, 04:19:38 am
content: Quote from: Robomeds on August 29, 2015, 03:10:33 amI only know because modemhead's Yokogawa has ADP mode and did some research some 2 years ago.http://mrmodemhead.com/blog/yokogawa-7534-03-multimeter/