Showing posts with label review. Show all posts
Showing posts with label review. Show all posts

Tuesday, January 9, 2018

Multimeter Ceramic Fuse Replacement

If you need replacing a fuse on your multimeter, you may find this reading useful. In this post I will share with you where you can buy cheap replacement ceramic fuses and how to make your DMM accept 5x20mm and 6x32mm fuses. I will also give some information regarding fuses and counterfeit fuses. In this case I am replacing the 1A fuse on a Uni-T UT61E multimeter, but this is applicable to most multimeters. You can read my review and teardown of the Uni-T UT61E multimeter here.

Ceramic vs. Glass fuses

The Uni-T UT61E, like many "better quality" DMM's, uses ceramic fuses. Ceramic fuses are better than the more common and cheaper glass fuses. They have a feature called High Rupture Capacity (HRC). Ceramic fuses have a ceramic tube, and all the empty space inside is filled with sand. If a very high current occurs, an extremely high amount of heat is created inside the fuse. That heat melts the sand filling of the fuse into glass. Since glass is an insulator, it suppresses any arc-over instantaneously. This behaviour minimizes the possibility of a dangerous high arc current, which is what happens if a normal glass fuse fails to break a heavy fault current. Unlike sand filled ceramic fuses, if a very high arc current goes through a common glass fuse, it can generate an explosion that shatters the fuse and lead to damages and serious injuries. 

Sources of 6x25mm ceramic fuses

The Uni-T UT61E uses two ceramic fuses, one 6x25mm 10A and one 6x25mm 1A. The original fuses are branded AsiaFuse BS1362. Unfortunately, it turns out that cheap BS1362 6x25mm ceramic fuses are hard to find. The more common BS1362 6x32mm fuse size is available from multiples sources though. And since the Uni-T UT61E PCB layout accepts 6x32mm fuses also, it's just a matter of moving one of the fuse holder terminals to a different position. Take a look a the following picture.


In the above picture, since a 6x25mm fuse was not available, I managed to use a 5x20mm glass fuse temporarily while my order of 6x25mm ceramic fuses did not arrive. It was a matter of carefully tightening the fuse support until it hold the smaller 5x20mm fuse securely in-place.


These are the BS1362 ceramic fuses I received from AliExpress. They are branded Bussmann and costed US $2.50 for a pack of 10. And here is the Uni-T 61E after the 1A fuse was replaced.


Unfortunately, after careful inspection and despite apparent good build quality, the fuses I received appear not to be genuine. However, since I determined they are safe to use (read below), I'm happy.

Buy BS1362 ceramic fuses from Banggood!

Counterfeit fuses 

Since branded ceramic fuses are much more expensive than glass fuses, there are counterfeits with varying levels of quality. In many cases it's very hard to tell if a ceramic fuse is genuine or not. One can visually inspect and compare the suspect fuse with an original fuse sourced from a reputable distributor. If you buy a set of ceramic fuses I recommend you open one to see if it is really filled with sand. Needless to say, counterfeit fuses can be dangerous!

BS1362 Fuse Specs Datasheet
Counterfeit Fuse Information
Review of Uni-T UT61E

Wednesday, September 20, 2017

BSide ADM04 Mini Multimeter Review & Teardown

The BSide ADM04 mini multimeter is a 3 1/2 digit small and inexpensive portable digital multimeter with some special features. One of the features is the non-contact voltage detection (NCV) function. This enables you to locate hidden live mains wires behind a wall. The ADM04 mini also has a Hold function and LCD backlite, something that even some more expensive multimeters don't have. But that's not all, it also has a spotlight! Yes, press a button and you can turn your multimeter into a flashlight. So, this is clearly a multimeter ideally suited to be carried around. Lets take a closer lock at the BSide ADM04 mini multimeter.

BSide ADM04 mini multimeter

Features:
3 1/2 digital LCD display.
Mini pocket Auto range digital multimeter.
Measure DC/AC voltage, DC/AC current, resistance, and diode & continuity check.
Data Hold function.
With NCV (Non-contact AC voltage detector) function.
With backlight and work light.
With protection case.
Low battery indication.
Auto power off.
Safety rating: CE CATIII 600V.

Specifications:
DCV: 200mV/2V/20V/200V+-(0.5%+3), 600V+-(0.8%+5)
ACV: 2V/20V/200V+-(0.8%+3), 600V+-(1.0%+5)
DCA: 200µA/2000µA/20mA/200mA+-(1.8%+5)
ACA: 200µA/2000µA/20mA/200mA+-(2.0%+5)
Resistance: 200Ω/2kΩ/20kΩ/200kΩ/2MΩ+-(1%+3), 20MΩ+-(1.2%+15)

General characteristics:
Operating Temperature & Humidity: 0~40°C(32~104 °F), <80% RH
Storage Temperature & Humidity: -10~60°C(14~140 °F), <70% RH
Product Size: 130x62x27mm(5.4"x2.5"x1.10")
Product net weight: 150g/0.34lb
Colour: Black + Blue
Power Supply: 2 x 1.5V AAA Batteries (NOT included)

Appearance
The first thing that catches your attention is the small size of the BSide ADM04 multimeter. Although not the World's smallest multimeter, it will fit a large pocket. The multimeter case is protected by a silicone sleeve. The silicone sleeve protects the multimeter from falls and prevents the multimeter from skidding on the work bench. You will also notice that the test leads are not the usual detachable banana type cables, but are instead attached permanently to the multimeter. Since the ADM04 does not have some functions that would require the use of more than two multimeter inputs, for example high currents measuring, there is no need for detachable multimeter test leads. The test leads appear to be of good quality. The probes have detachable sleeves.

BSide ADM04 mini multimeter backlight

Non-contact voltage detection function
To use the non-contact voltage detection feature put the multimeter rotary switch in any position other than Off and point the bumpy part of the top of the multimeter to where the wires would be. If live AC wires are detected an LED near the top of the LCD will turn red. My tests show that the multimeter can detect live AC mains wires behind walls as long the wires are not to far away or the wall is not made of cement. Mains wires should be easily detected in plaster walls. Detection distance will vary, but it should work at a distance of up to about 10cm.

Voltage test
Both DC and AC measurements where within the accuracy specifications.

Current test
Current tests where within the accuracy specifications. Note that the ADM04 multimeter is capable of measuring only up to 200mA maximum current.

Diode test
Diode test range is 1V with 0.001V resolution and about 1mA test current. The display shows the approximate value of diode forward voltage drop. Open circuit voltage is about 1.6V which will be a problem when testing some LED's.

Continuity test
The built-in buzzer sounds when the measured resistance is less than about 50Ω. Response time is not fast, but it's OK.

Hold function
Reading values can be frozen on the LCD by pressing the hold button. The multimeter does not have auto-hold function.

Backlight and flashlight
LCD backlight is turned On by pressing the backlight button for 2 seconds. Backlight turns Off automatically after 15 seconds. The flashlight consists in a white LED with a lens and is activated simultaneously with the LCD backlight.

Test leads
The test leads are rated 600V CATIII/1KV CATII. They appear to be of reasonably good quality and made from silicone wire. The probes have detachable sleeves.

Battery replacement
The BSide ADM04 mini multimeter is powered by 2x AAA batteries. The battery compartment can be opened by removing a screw on the back.

Fuse replacement
The multimeter uses a single 250V 250mA ceramic fuse. To replace the fuse it is necessary to open the multimeter case.


Tear-down
The multimeter can be opened by removing the protective rubber case and unscrewing four screws. The battery compartment connects to the main board by two springs.

BSide ADM04 mini multimeter battery replacement

The multimeter uses a single board design. Component layout is good without any bodge wires in sight. Soldering is also good.

BSide ADM04 mini multimeter main board pcb teardown

Input protection is accomplished by a single 250V 250mA ceramic fuse, two PTC's, diodes and resistors. Since this multimeter does not have a high current input, the usual wire current shunt and high current fuse are not present.


Verdict
The BSide ADM04 mini multimeter is a 3 1/2 digit portable digital multimeter with some welcomed added features and good build quality. The multimeter comes with a user manual in good English, something that more often than not is not the case. If you don't need to measure currents higher than 200mA, this is a good little multimeter to carry around. It is adequate for low voltage, low current circuits.


Need a better multimeter? Then take a look at my Uni-T UT61E multimeter review.
New to multimeters? Read my Multimeter buying guide.

Tuesday, August 29, 2017

BENJIE S5 / AGPTEK M20 Music Player Review & Teardown

This is a full review and tear-down of the Benjie S5 / AGPTEK M20 Hi-Fi music player. The Benjie S5 is a portable music player that has gained recognition from users for its sound quality and small price. The small player supports the most popular compressed and uncompressed audio formats: APE, FLAC, OGG, MP3, WMA, AAC-LC, WAV and ACELP. That means you can probably play all your music library without the need to convert any music files. The player has 8GB of internal memory and supports up to 64GB microSD cards. Playing time is 14 hours. The Benjie S5/AGPTEK M20 is also an FM stereo receiver and voice recorder.

If you play music on your cellphone, you probably can notice some interference noises. It's very difficult to suppress those unwanted noises on a cellphone. If you want better audio quality, a dedicated music player (like the Benjie S5/AGPTEK M20) is the way to go! 

Benjie S5 Music Player, box, earphones & USB cable.

The heart of the Benjie S5/AGPTEK M20 player is the Actions Semiconductor ATJ2127 single-chip highly-integrated digital multimedia solution. The ATJ2127 includes an audio decoder, record capabilities and USB interface. It has a built-in Sigma-Delta D/A converter and includes a headphone driver to directly drive low impedance headphones. 

Specs
Supported music formats: APE, FLAC, OGG, MP3, WMA, AAC-LC, WAV and ACELP
Memory capacity: 8 GB (internal)
External memory: supports up to 64GB microSD cards
Playing time: 14 hours (by earphone)
Charging time: 2 hours
Battery capacity: 3.7V/280 mAh
Charging method: micro USB
Screen: OLED 1"
Firmware upgradable?: Yes
FM radio?: Yes

The player is sold under different brand names as Benjie S5, Benjie M20, AGPTEK M20 and probably others. Hardware and functionality is the same, however AGPTEK does provide firmware updates from their site while (at time of writing) Benjie does not provide firmware updates. It appears however that you can update your Benjie S5 branded player with the AGPTEK M20 firmware without issues. I have done the update without issues and it does provide some (minor) improvements. But, since no significant improvement has been made, I wouldn't bother updating at the moment.

The case is made from Zinc alloy with an aluminium back. There are no screws is sight, the back plate is held in place with double sided tape. I like the design, but I find the case edges a bit too sharp.


Benjie S5 Music Player back.

Interface 
The player fits the palm off your hands nicely and has nice (but not perfect) control interface. The front face has a small OLED screen, touch control interface and one physical play/pause/select button. Volume control has two dedicated buttons on the left side and the right side has an on/off button and a lock button. The touch control area has no backlight, which means you can't reliably access some functions in the dark. Fortunately, the skip and back functions are available through the Vol Up and Vol Down buttons when the screen is turned off. 

The user interface can be a bit confusing. There is some inconsistency in the use of the Up, Down, Previous, Next buttons when using the settings menu and the FM radio. Sometimes you expect to use the next/previous control, but the interface assigned the function to the up/down control intead. Overall however, the interface works reasonably well.
 
If, like me, you have not properly tagged all your music, you may like to know that the player has the Folder view option, where you just select the folder where the album you want to play is located and it will play all tracks in that folder.
 
The player uses its USB connection for charging and file transfer. File transfer is fast.

Audio quality 
What surprises me most about the Benjie S5 is the audio quality. Despite being a low cost entry level Hi-Fi player with a lowish D/A+PA SNR of only >91dB and a 16-bit Sigma-Delta D/A, listening to a wide range of music revealed that the Benjie S5 has very good sound quality. For even better sound quality you would need to pay more than double the price of the Benjie S5 or AGPTEK M20!

Frequency response seems flat, which is good. Using a good set of earphones or headphones the player has plenty of bass and highs even with the equalizer turned off. The Benjie S5/AGPTEK M20 can drive 16 Ohm, 32 Ohm or 64 Ohm headphones easily. It can also drive high sensitivity 100 Ohm headphones, but at a lower maximum sound level. If you want or need, you have 6 equalizer settings to choose from, but unfortunately no custom setting. 

The earphones included with my player deliver good but not great sound. These are all white and with a different cable than other earphones delivered with the Benjie S5. I suggest you get a better pair of earphones or headphones.

The sound on the Benjie S5/AGPTEK M20 is "clean", with no discernible noises. 

Gap-less playback 
Gap-less playback means a music player can play audio tracks without any silence (gap) between them. This means that you can listen to several consecutive tracks as it was one continuous single track. This is desirable because some albums have tracks that are meant to follow the previous track immediately, without the usual silence gap. Unfortunately the player is not capable of gap-less playback. The sound gap is very short, but it is noticeable. This is apparent, for example, on Steve Vai's Sound Theories Vol I & II. Not a deal-breaker though.

Screen 
The Benjie S5/AGPTEK M20 uses a small 1" OLED display. Despite the small size, the display is quite readable if your eyesight is good, but only indoors or in the shade. Like with so many other players, it's very hard to see the display outdoors on a sunny day. Besides battery level and play mode, the player displays track number, track name, album name, track duration and playback position, but it does not display file bit-rate or type. Only by file name you can know what type of file you are playing. 

Benjie S5 Music Player.

FM radio 
The Benjie S5, AGPTEK M20 has an FM Stereo receiver with 30 pre-sets. Reception with a strong enough signal is good, but weak stations may be hard to receive. FM radio function is performed by the RDA5807M IC. Although the RDA5807M is RDS capable, unfortunately the capability is not implemented by the current firmware. This means no RDS information is displayed and stations are named and memorized with their frequency value and not their name. Recording FM radio is also not possible. 

Benjie S5 FM radio.

Battery
The player uses its USB connection for charging the 3.7V 280 mAh Li-on battery using the provided micro USB to standard USB male cable. Charging time is 2 hours. I have not measured exact battery duration, but the claimed 14 hours seem reasonably accurate. Stand-by time is claimed to be 560 days.


Tear-down: 
Opening the player is not easy, the back is held with double sided tape.

Benjie S5 / AGPTEK M20 teardown.

With the back removed you have access to the Li-on battery.

Benjie S5 / AGPTEK M20 teardown.
 
The main board. Simple and tidy!
 
Benjie S5 / AGPTEK M20 teardown.

Removing the main board exposes the touch controller board, the OLED screen, internal memory, headphone connector and play/pause/select button.

Manufacturer product information 
Benjie S5, M20 product page
AGPTEK M20 product page
Action Semiconductor ATJ212X specs 

BUY THE BENJIE S5 FROM BANGGOOD

Note: I may get a small fee (at no extra cost to you) if you use the link to buy the player. Thank you for your support!

Tuesday, January 10, 2017

Uni-T UT61E Multimeter Review & Teardown

In this post I will be reviewing the Uni-T UT61E digital multimeter. The UT61E DMM is one of the most popular multimeters available. But is it any good? Lets find out!

If you are looking to buy a multimeter then please read my previous post where I give some advice on choosing and buying a multimeter.

The Uni-T UT61E is part of the UT61 family of DMM's from Uni-Trend Technology, a well known Chinese test and measurement solutions provider. You can choose from several models: UT61A, UT61B, UT61C, UT61D and UT61E. The models all look the same but they have different features and specifications. So compare the different models carefully before buying or you might get a bad surprise!

UT61E + accessories


Uni-T UT61 Features
These are the common UT61 multimeter series features taken from the Uni-T web site:

1、Large LCD screen;
2、High resolution analog pointer display;
3、Full range overload protection;
4、Data hold, REL, Peak value measurement;
5、Low battery indication;
6、External interface supports RS-232C and USB cable.

UT61 Series can measure AC/DC voltage and current (UT61D, UT61E has true RMS), resistance, diode, circuit continuity, capacitance, frequency, temperature, hFE, electromagnetic induction, etc. UT61 Series complies with the standard IEC61010: CAT. III 1000V, CAT.IV 600V. 

And these are the specifications and feature list for the UT61E model:

SpecificationsRangeBest Accuracy
DC Voltage (V)220mV/2.2V/22V/220V/1000V±(0.1%+2) 
AC Voltage (V)220mV/2.2V/22V/220V/750V ±(0.8%+10) 
DC Current (A)200μA/2200μA/22mA/220mA/2.2A/10A± (0.5%+10) 
AC Current (A)200μA/2200μA/22mA/220mA/2.2A/10A±(0.8%+10)
Resistance (Ω)220Ω/2.2kΩ/22kΩ/220kΩ/2.2MΩ/22MΩ/220MΩ±(0.5%+10)
Capacitance (F)22nF/220nF/2.2μF/22μF/220μF/2.2mF/22mF/220mF±(3.0%+5) 
Frequency (Hz)10Hz-220MHz±(0.01%+5) 
Features
Display Count 22000
Auto Range √  
True RMS √  
Bandwidth (Hz) 45Hz ~10kHz
Duty Cycle0.1% ~ 99.9% √  
Diode √  
Continuity Buzzer √  
Low Battery Indication≤7.5V√  
Data Hold √  
Relative Mode √  
Peak Value √  
RS-232 √  
Analogue Bar Graph 46
Input Protection √  
Input Impedance for DCVAround 10MΩ√  
General Characteristic 
Power9V Battery(6F22) 
LCD Size65mm × 43 mm
Product ColorRed and Grey 
Product Net Weight370g 
Product Size180mm × 87mm × 47 mm 
Standard AccessoriesBattery, Test Lead,Muli-Purpose Socket,RS-232 Interface Cable,PC Software CD
Standard Individual PackingGift Box, English Manual 
Standard Quantity Per Carton22 PCs
Standard Carton Measurement455mm×335mm×375mm
Standard Carton Gross Weight15.5 Kg 
Optional Accessories*USB Interface Cable

If you compare between the models, you can see that the UT61E has the best specs. It is a 22000 count DMM with better accuracy. However, it does not have LCD backlight (although it's possible to add it) and doesn't take temperature measurements.

UT61E Teardown pictures
The UT61E comes apart easily by turning just 3 screws.

Inside UT61E - 1
Once opened you have access to replaceable components, like the 2 fuses. These are ceramic good quality fuses, not cheap glass fuses. As it can bee seen, the resistor network is now shielded. An improvement over previous UT61E versions.

Inside UT61E - 2

Removing the PCB exposes the top PCB layer with the rotary switch. The main multimeter chip is the Cyrustek ES51922 (ES51922A). True RMS feature is implemented by use of the AD737J True RMS-To-DC converter chip.

UT61E back and battery cover

To replace the battery only one screw needs to be unscrewed. 

Safety - Input protection
When I disassembled my Uni-T UT61E I got a very nice surprise! I immediately noticed that my UT61E has better input protection than expected. As you can see, the PCB has been redesigned and (among other improvements), there are additional input protection components on the PCB compared to other UT61E's. So, it seems Uni-T has improved the input protection on the Uni-T UT61E. There is however still room for input protection improvement. Markings for additional input protection components can bee seen on the PCB board. The following image shows the two different versions of the UT61E:

Uni-T UT61E input protection
Two different versions of the UT61E

The PCB of my UT61E (on the right) is marked 150507-9C, while the other one is marked 150507-7.

Although there are no safety certification markings on the multimeter itself, on the box there is some reference to UL certification.

Accessories
The multimeter comes with a pair of test leads, multi-purpose socket, RS232C interface cable (USB available at extra cost) and software on CD-ROM. The multi-purpose socket inserts on two of the multimeter inputs and enables component testing without the probes. It accepts components with wire leads and smd components.

Accuracy testing
I have tested the UT61E accuracy with an AD584 high precision voltage reference module. The module has four reference DC voltages: 2.5V, 5V, 7.5V and 10V. All readings where well within the UT61E accuracy specifications. Since I do not have high enough precision resistors and capacitors I did not test the accuracy of these measurements. However, readings seem correct and, since the precision of low DC voltages are usually the most important, I don't worry about it. Please watch the YouTube video bellow:


Data logging
UT61E Interface ProgramOne of the major features of all Uni-T UT61 multimeters is its data logging capability. With data logging you are able to automatically record measurements from your multimeter to a computer. The provided software is somewhat basic, but it is simple to use. Connection is made by the provided custom RS232C cable. Connection with the multimeter is optical, so it is isolated and safe. If your computer doesn't have an RS232 serial port (many don't) you can use an serial to USB adapter. The interface software, driver and PDF manual come in the CD-ROM, but can also be downloaded from the official Uni-T UT61E page. Current version is 4.0.1.

Other tests and thoughts
The UT61E also passed the continuity test. It has a reasonably quick response when you short the test leads, but be sure the tips are making a good contact. Measurements are reasonably quick too. Only high value capacitors take more time to get a stable reading, but this is expected and is mentioned in the manual. According to the ES51922 specs, it can make two measurements every second and I think that's about right.

The selector switch is not top quality. It's not too loose or to hard to turn, but it's not very precise. I don't think this is a problem tough. 

Data logging works without problems, but I would prefer the multimeter came with a USB cable instead of RS232. Most computers don't even have the RS232 serial interface anymore! But again this is not a big issue because you can use an RS232 to USB adapter. 

If you are one of those people that never reads the product manual this is not an issue for you. But you should read the manual and, although it is fairly extensive, it's unnecessarily confusing. It is confusing because Uni-T supplies the same manual for all versions of the UT61 multimeter. So, some things apply to one model but not others and you have to pay attention.

  
Verdict
I find the Uni-T UT61E is an excellent budget digital multimeter. I have the UT61E for some time now and it has not disappointed me yet. With its 22000 counts large and clear display, True RMS, PC connectivity and improved input protection, the UT61E has to be one of the best multimeters you can buy for under 50 USD.

Want to buy a Unit-T 61E?
I buy most of my electronics, tools and measuring equipment from Dealextreme and Banggood in China. They have low prices, friendly and helpful staff and will offer a solution if something goes wrong with your order. They have warehouses in Europe and the USA and can provide faster delivery for many of the items. I may get a small fee if you buy from them through links in MakerCorner. Thank you for your support!

Buy the Unit-T 61E from Dealextreme
Buy the Unit-T 61E from Banggood

Download the Unit UT61E user manual here.
Download Uni-T UT61E interface software and manual here