LongRunner's Mini-review Collection
Posted: April 25th, 2016, 11:51 pm
In order to pass the time I'd otherwise spend doing pretty much nothing meaningful…
Firstly, a brief rundown on the definitions (at least, as I use them):
Here are the mini-reviews so far:
Jaycar "Digitech" QP-2000 power point & earth leakage tester (Australia/NZ only)
So, this is obviously one of those three-neon devices (with all their limitations - U.S. site, but the concept is unchanged), combined with an ELCB/RCD tester with four test currents (10/15/30/100mA). I got this one years ago, so the orange casing has faded slightly, but Jaycar still has them. And already there's a typo: "Correct wring"? (Although they appear to have fixed that, going by the photo they now provide.) The labels indicating the wires each neon is connected between are also wrong; their correct order, from top to bottom, is: L-N, L-E, N-E. (Also fixed in the revision, they are no longer specifically marked as such.) It's also indicated (in broken English) that the instructions are on the back:
To its credit, it does work as described, more-or-less. Except for the open neutral condition:
This post would, of course, be pretty boring without actually going inside this thing. So here it is:
Right away we get to see the cheap circuit board, with horrendous soldering. <insert barf smilie here>
The way the polarity-indicating neon lamps are connected is nothing unusual - just series 100k±5% 0.25W carbon film resistors (which actually manage to look cheap-and-nasty, although they at least measure within tolerance) limiting the current to ≈1.5mA through each. A bit close to their rating for comfort, but not too bad. The more interesting part is the ELCB/RCD test.
The highest test current of 100mA uses a series pair of 1.2k±1% 1W (going by the physical dimensions) metal film resistors (R4 and R5). The resistance itself is spot on (for 240V), but when testing that current they will dissipate 12W each until the protective device trips or the operator releases the button. Oddly enough, the PCB actually provides the option of installing 2W resistors here.
For 30mA a 5.6k±5% 0.25W carbon film resistor (R3) is added in series with the pair. Again, the correct ohms, but now this resistor dissipates 5.04W!! Sure enough, plugging the unit into an unprotected outlet and holding down the button with the switch set to 30mA burned it out:
(I see enough room on the PCB that they could have designed it to accommodate a 2W resistor there if they cared to…)
For 15mA an 8.2k±5% 0.25W resistor (R2) is added in series with those. Now the total resistance is slightly higher than "correct" (but to be fair, RCDs are meant to respond a bit below their "nominal" trip current, and 8.2k is the closest E24 value). This resistor has to survive 1.8W, which isn't quite as bad but still 7.2× more than it's rated for (unless it's a "mini" 0.5-watter, but I can't tell that from looking at it). Finally, the 10mA setting adds an identical 8.2k resistor (R1) in series with the other four. Then R1 and R2 take "only" 793mW each.
As for the green LEDs that indicate which leakage current the slide switch is set to (as if you're using it in the dark or whatever…), they are lit with a simple half‑wave rectifier (1N4004 in combination with a 47k±1% 0.5W metal film resistor, which works at 613mW), connected between L and N to avoid an errant leakage current (to earth, anyway). This part also explains what's up with the unit's response to interrupting the neutral connection.
Even the choice of cord strikes me as odd. It's (allegedly) 1.0mm², which is a bit excessive given that this thing would catch on fire long before maxing out even 0.5mm² (the smallest allowed, and 0.75mm² is much more usual). Actually, even hair-thin 36AWG (≈0.013mm², even smaller than a single strand of a typical mains cord) wire could theoretically sustain 100mA - although that would break way too easily. And look at this:
It seems to be a counterfeit cord (even if the dimensions are about right). And when flexed, it makes noise a bit like that expected of a foil-shielded cable.
Overall, I give it a D−; it's mostly functional at its intended purpose, but that's about it.
Stay tuned for more mini- and micro-reviews.
Firstly, a brief rundown on the definitions (at least, as I use them):
- A micro-review is something that amounts to little more than a summary of (some of) the item's properties.
These can be multiple per post and will not have pictures unless they're the easiest way to convey something important. - A mini-review is more detailed than a micro-review, but not enough to qualify as a full review (at least by my standards, which require proper test methodology to make the cut).
Here are the mini-reviews so far:
- Jaycar "Digitech" QP-2000 power point & earth leakage tester (Australia/NZ only) (this post) – marginally useful, very cheaply (and nastily) constructed.
- Official Nintendo DSi/3DS AC adapter (WAP-002) (Australia/NZ version) – modest, but well-made.
- Allocacoc PowerCube Extended and PowerCube Extended USB (Australia/NZ version) – elegant, but with a few faults.
- Omniwheel's 3DStick+ – nice enough, provided you can tolerate the somewhat rough 3D-printed finish.
- Nintendo (3)DS 16-game case (not first-party, but officially licensed nonetheless) – looks alright, until you actually try to fit the games in.
(And I wouldn't have complained if it was unlicensed. ) - Stylux T-869 "Trax" desk lamp (Australia only) – alright looking, but a bit lazy on the wiring front.
- Kambrook KFH660 – a basic but competent 2400W fan heater. (Full review published now.)
(See also: KFH600 addendum, with internal differences) - Trent & Steele TS5 – a simple rice cooker, of middling build quality.
- Goldair GSFH110/FH-07A (also available under other brands) – a lesson in how not to build a fan heater.
- Projecta SB200SP automotive booster cable – a typical hardware-store piece of crap.
- A surge protector…? A detailed look at the reality (as opposed to popular belief) of these things.
- Laser PW-4ADAPT set – if this is legal, then something's wrong with Australian electrical safety standards.
- DēLonghi HVS3032 (pictureless) – a fan heater that's relatively expensive to buy, but built like a tank to justify it (unlike far too many pretentious heaters). (Full review of the EX:3 revision published now.)
- Sunbeam RC5600 (pictureless) – after breaking the lid knob off the TS5, I got a more robust rice cooker to replace it.
- Blaupunkt BCH500B – another once-beloved audio name (like Akai) zombified onto cheap home appliances, including heaters; but is it still worth considering the 500-watter?
- Jackson Industries Power Block (Australia/NZ) – like the PowerCube, but better built?
- Connected Switchgear (Australia) (part 1, 2) – are they as serious about quality as they claim?
- Click CLKPB4, CLKPB6 and C6PB (Australia/NZ) – can cheap power-boards be made competently after all?
- Ningbo Kaifeng KF-MSD-4A (Australia/NZ) – best of the Chinese-made power-boards?
- Crest PWC05041 (Cixi Yidong Electronics TA‑7) (Australia/NZ) – one mechanical plug-in time-switch among many, flawed but fixable.
- Arlec PB12PP and Crest PW4PBS10 (Australia/NZ) – a follow-up to my previous power-board posts, checking out their more-expensive relatives.
- Hager WBP4S, WBP2S outlets and WBSV1 light switch (Australia/NZ) – is your Clipsal C2015D4 getting yellower by the year? Suffer no longer…
- Round 1
- Round 2
- Round 3 – did you know there was a way to make a more decisive thermal fuse, even with 1997 technology?
- Round 4 including a rant about just how much trouble you can get people into by butchering semantics.
- Round 5
- Round 6 – is there still hope for decent power-boards/strips? (This post was before I got the Jackson Power Block and various Kaifeng models.)
- Round 7 – I seem to be doing quite well at picking decent appliances. I wonder how long my streak will continue…
- Round 8 – if you must gamble with products, then at least do it on op-shop/thrift-store items so the losses aren't so bad.
- Round 9 – perhaps stretching the definition, but also comments on the pros and cons of electric frying-pans.
- Round 10 – will I find any table or desk lamp that isn't lousy?
- Software remarks – a diversion while living in a crowded house.
- Round 11 – how decent of a computer mouse can we get?
- Round 12 – foreign rewireable plugs and another travel adapter…
- Round 13 – is the smallest of Vornado's line-up worthwhile?
- Round 14 – kitchen stuff, I suppose…
- Round 15 – more second-hand shenanigans…
- Round 16 – the continuing tragedy when non-gamers try to make gaming equipment…
- Round 17 – just a few loose ends really…
- Round 18
- Round 19 – an easy place to obtain the Kaifeng KF-MSD-6A (and KF-MSD-4A), and I get a water gun.
- Round 20 – a cheap discounted mouse, a socket tester, and yet another travel adapter…
- Round 21 – an LED flashlight/downlight duo (or trio if you count that I have two of the downlight).
- Round 22 – yet more of the best and worst second-hand stuff (albeit with more detail about the worst)…
- Round 23 – three large appliances and a few small non-electrical housewares…
- Round 24 – picking the best (?) downlight at Rexel, is it good enough?
- Round 25 – another new (and better) rice cooker, and the disappointments of late Australian manufacturing…
- Round 26 – although far from perfect, at least some shuttered power-boards are available.
- Round 27 – some cheap plastic kettles are safer than others…
- Round 28 – can I still find a decent HDD enclosure in this wasteland of rotten “reviews”?
- Round 29 – are you looking for a radiant heater and tempted by the older tumble-proof Kambrook models? Here's some more context before you buy…
- Round 30 (final) – finally, something other than a room heater from DēLonghi!
Jaycar "Digitech" QP-2000 power point & earth leakage tester (Australia/NZ only)
So, this is obviously one of those three-neon devices (with all their limitations - U.S. site, but the concept is unchanged), combined with an ELCB/RCD tester with four test currents (10/15/30/100mA). I got this one years ago, so the orange casing has faded slightly, but Jaycar still has them. And already there's a typo: "Correct wring"? (Although they appear to have fixed that, going by the photo they now provide.) The labels indicating the wires each neon is connected between are also wrong; their correct order, from top to bottom, is: L-N, L-E, N-E. (Also fixed in the revision, they are no longer specifically marked as such.) It's also indicated (in broken English) that the instructions are on the back:
To its credit, it does work as described, more-or-less. Except for the open neutral condition:
This post would, of course, be pretty boring without actually going inside this thing. So here it is:
Right away we get to see the cheap circuit board, with horrendous soldering. <insert barf smilie here>
The way the polarity-indicating neon lamps are connected is nothing unusual - just series 100k±5% 0.25W carbon film resistors (which actually manage to look cheap-and-nasty, although they at least measure within tolerance) limiting the current to ≈1.5mA through each. A bit close to their rating for comfort, but not too bad. The more interesting part is the ELCB/RCD test.
The highest test current of 100mA uses a series pair of 1.2k±1% 1W (going by the physical dimensions) metal film resistors (R4 and R5). The resistance itself is spot on (for 240V), but when testing that current they will dissipate 12W each until the protective device trips or the operator releases the button. Oddly enough, the PCB actually provides the option of installing 2W resistors here.
For 30mA a 5.6k±5% 0.25W carbon film resistor (R3) is added in series with the pair. Again, the correct ohms, but now this resistor dissipates 5.04W!! Sure enough, plugging the unit into an unprotected outlet and holding down the button with the switch set to 30mA burned it out:
(I see enough room on the PCB that they could have designed it to accommodate a 2W resistor there if they cared to…)
For 15mA an 8.2k±5% 0.25W resistor (R2) is added in series with those. Now the total resistance is slightly higher than "correct" (but to be fair, RCDs are meant to respond a bit below their "nominal" trip current, and 8.2k is the closest E24 value). This resistor has to survive 1.8W, which isn't quite as bad but still 7.2× more than it's rated for (unless it's a "mini" 0.5-watter, but I can't tell that from looking at it). Finally, the 10mA setting adds an identical 8.2k resistor (R1) in series with the other four. Then R1 and R2 take "only" 793mW each.
As for the green LEDs that indicate which leakage current the slide switch is set to (as if you're using it in the dark or whatever…), they are lit with a simple half‑wave rectifier (1N4004 in combination with a 47k±1% 0.5W metal film resistor, which works at 613mW), connected between L and N to avoid an errant leakage current (to earth, anyway). This part also explains what's up with the unit's response to interrupting the neutral connection.
Even the choice of cord strikes me as odd. It's (allegedly) 1.0mm², which is a bit excessive given that this thing would catch on fire long before maxing out even 0.5mm² (the smallest allowed, and 0.75mm² is much more usual). Actually, even hair-thin 36AWG (≈0.013mm², even smaller than a single strand of a typical mains cord) wire could theoretically sustain 100mA - although that would break way too easily. And look at this:
It seems to be a counterfeit cord (even if the dimensions are about right). And when flexed, it makes noise a bit like that expected of a foil-shielded cable.
Overall, I give it a D−; it's mostly functional at its intended purpose, but that's about it.
Stay tuned for more mini- and micro-reviews.