BK Precision 2709b or 2712 ? - Page 1
Forum section: electronics / general

author: TSX420J
author_rank: Newbie
timestamp: April 13, 2012, 06:36:24 am
content: Hi, I am new to the forum and have seen Dave's shootout featuring the 2709b. I was most interested in buying this multimeter because of its accuracy, range and build quality. I went to BKP's website and saw there was a 2712.I am new to troubleshooting electronic components and am learning new things everyday. I want to use this DMM for checking caps, resistors and diodes on older electronics such as old game consoles and power supplies.I have a couple of repair projects in the works and need to buy a good DMM to be able to diagnose a PSU of a sega dreamcast console. It has a couple of caps, 10v 2200uf, 10v 3300uf, 35v 470uf and a 10v 470uf one.My questions are, which DMM is better suited for my needs out of the two and would they be able to measure the capacitance of these caps? I'm sorry for my noobness I am unfamiliar with the way the ratings work. I want to learn more. Any help is appreciated thanks!!2712http://bkprecision.com/downloads/datasheets/2712_datasheet.pdfCapacitance Ranges: 4 nF, 40 nF, 400 nF, 4 uF, 40 uFResolution: 1 pF, 10 pF, 100 pF, 1 nF, 10 nFAccuracy: 4 nF range: ±(3.0% rdg + 20 dgts)40 nF to 400 nF ranges: ±(3.0% rdg + 5 dgts)4 uF to 20 uF ranges: ±(3.0% rdg + 5 dgts)20 uF to 40 uF ranges: ±(5.0% rdg + 5 dgts)2709bhttp://bkprecision.com/downloads/datasheets/2709B_datasheet.pdfCapacitance Ranges: 6.6 nF , 66 nF, 660 nF, 6.6 uF, 66 uF, 660 uF, 6.6 mF, 66 mFResolution: 1 pF, 10 pF, 100 pF, 1 nF, 10 nF, 100 nF, 1 uF, 10 uFAccuracy: 6.6 nF range: ±(3.0 % rdg + 30 dgts)66 nF to 660 uF ranges: ±(3.0 % rdg + 5 dgts)6.6 mF to 66 mF ranges: ±(5.0 % rdg + 20 dgts)

author: david77
author_rank: Frequent Contributor
timestamp: April 13, 2012, 08:19:28 am
content: In January I decided I needed a new meter and after watching Dave's shootout videos decided to get the 2709B.It is a really nice meter for the money. The build quality is good, the switch is very nice - though a bit small. Continuity beeper is fast, accurate and loud wich is good. Autoranging is fast and the display is clear and good to read, not too many gimmicks that no-one really needs.Input protection seems to work well. Do discharge every cap you measure! I already managed to blow the 500mA fuse by measuring a used cap that's been in storage for years but obviously still held some charge.True RMS frequency range is not so good, it only goes up to a few kHz. Can't remember where it starts do drop off exactly, I think around 3-3,5kHz.But it has some annoying habits and does some weird things.1. The beeping. It is f***ing annoying and incredibly loud. Everytime you switch ranges it goes BEEEEP!!! Why?!Oddly it doesn't beep when switching it into Hz mode.Before it auto powers down it gives a few short beeps and one long beep when actually switching off. You can override the auto power down mode by pressing the Range (?) button while switching on.I work a lot at night when it's quiet, the beeping really grates then.2. It doesn't auto range into the 660mV range. Very annoying indeed. I'm pretty sure that's some firmware bug, not a feature as it doesn't make sense.3. The magnet strap thing. Nice idea, I can see that coming in handy.But: You can't put the meter flat on the bench with the strap attached, it wobbles from side to side and is impossible to use with one hand. So you take the strap off, wich means it's gone. Lost forever.4. The 4mm input jacks. I'm not sure I like them, they seem very wobbly when not used with shrouded 4mm plugs. I have a feeling that might one day become a problem.

author: TSX420J
author_rank: Newbie
timestamp: April 13, 2012, 09:04:11 am
content: Thanks, good info.Would I be able to check the caps mentioned above with the 2709b or 2712? They seem out of range, correct me if I am wrong please. I don't want to dive into a 100+ dollars DMM to later find out it is insufficient for my needs. Thanks again for the reply!

author: david77
author_rank: Frequent Contributor
timestamp: April 13, 2012, 09:10:16 am
content: The 2709B goes up to 66millifarad = 6600µf, so yes it can measure them. The 2712 hits the wall at 40µf.I wouldn't get hung up about the cap range on a meter, though. It's not that often used in real life. If you want to know about the health of your caps what you want to know is the ESR value and I'm not aware of any multimeter that can do that.A standard DMM will give you a ball park figure on the capacity, with electrolytics that's enough. For really accurate cap measurements you're probably better off with a LCR meter.

author: ejeffrey
author_rank: Super Contributor
timestamp: April 13, 2012, 09:12:47 am
content: I say get the 2709B. I have the 2912, and I don't really like it. The autoranging and the continuity beeper are way to slow. I haven't seen the 2709B in person, but I think the display on the 2912 is a bit worse.I don't think the improved accuracy and resolution is worth the tradeoff. If you for some reason need the DC+AC RMS voltage you will need to get the 2912, but otherwise I think the 2709B is a better general purpose meter.The 2709B can also measure much larger capacitance values, which sounds like something you are interested in.

author: robrenz
author_rank: Super Contributor
timestamp: April 13, 2012, 12:02:54 pm
content: If you already have a acceptable DMM It sounds like you may be better off with a LCR meter since all your stated needs are capacitance. It would give you ESR which would be very handy for cap condition assesment. They also measure low resistance better than most DMM's (most have at least .001 Ohm resolution). There are several hand held's mentioned on the forum, IET DE-5000, mastech, Agilent etc.

author: TSX420J
author_rank: Newbie
timestamp: April 13, 2012, 04:34:19 pm
content: Quote from: david77 on April 13, 2012, 09:10:16 amAwesome, thanks for clarifying that for me!! 66mf=6600µf, Great! Ok, so with a DMM I'll get a relative reading of caps, but nothing exact. Will I at least be able to know if I have a faulty cap when checking with a DMM? Thanks!Quote from: ejeffrey on April 13, 2012, 09:12:47 amAwesome info, thanks!! Ill also be using this DMM to measure the output voltage on a basic wall wart power supplies and their internal parts like, transformers. Would the DC+AC RMS capability of the 2912 serve me better or do you think that the 2709b would be enough? I have a project in the works where I want to convert an existing 10v 850ma wal wart power supply to 9.5v 1.5a by swapping some internal parts. The 2709b seems like it should be more than sufficient for these kind of projects of mine, right? Thanks for the reply!!Quote from: robrenz on April 13, 2012, 12:02:54 pmThis will be my first DMM. I figure, since it is my first, I might as well do it right. I was planning on using the DMM for simple checks just to determine what components may be bad or going bad on some boards. For example, I have this Sega Dreamcast game console internal power supply. It wasn't powering the unit on. It had a radial fuse I thought might be bad, so I bought a new one and swapped out the fuse. It still will not power on. So, rather to waste more money on components, I would like to pinpoint the problematic component. Would I be able to do this with just a DMM or will I have to buy a LCR as well. Should I buy both? If so I do not think I can afford to buy a 2709b plus a decent LCR. I do need a DMM though because of other projects that will require that I check voltages and continuity. Thanks for the reply!P.S. I have checked the the Dreamcast with another PSU and it worked fine. All the caps, and solder joints look physically fine as well. At this point I need to be able to check the transformers, diodes, resistors and linear voltage regulators for problems.Thanks so much guys, for the knowledge and help!! I appreciate the help. I have been reading for days but didn't find much info on this subject. Thanks!!

author: ejeffrey
author_rank: Super Contributor
timestamp: April 13, 2012, 06:10:39 pm
content: Quote from: TSX420J on April 13, 2012, 04:34:19 pmTo clarify, the DC+AC rms is not a dual-display mode. It measures the total RMS value, including the DC component. So if you have a 5 volt supply with 1 volt rms ripple, it will read 5.1 volt RMS -- not very useful. The DC+AC rms is good for measuring things like a PWM driven resistive heater. For measuring power supply ripple you want the ordinary AC RMS. Fancier meters like some of the Agilent meters and many bench meters can do dual-display where they show the DC voltage and the RMS ripple simultaneously. This is handy but not essential.

author: david77
author_rank: Frequent Contributor
timestamp: April 13, 2012, 06:40:16 pm
content: Quote from: TSX420J on April 13, 2012, 04:34:19 pmIMHO you are right, you need a multimeter not a LCR meter for simple troubleshooting. The 2709 is a very good starting point and will do nearly everything you need.You might want to think about getting or building a ESR meter as it can help finding capacitor related problems. Even a cap that measures perfectly capacity-wise can still be the cause of a circuit not working. Search the forum for ESR meter, there's been a lot of talk about it.What's more important is to try and understand what the circuit you want to troubleshoot does and how it does it. I think that helps a lot to get away from stabbing around cluelessly in the dark, replacing things willy-nilly is not an elegant solution, but sometimes it's unavoidable.If you understand how a SMPS works in theory and know the possible topologies it will make it easier to identify the culprit, you get there faster.With enough practice and experience you'll be able to identify some typical problems without making a single measurement.

author: TSX420J
author_rank: Newbie
timestamp: April 13, 2012, 06:50:19 pm
content: Quote from: ejeffrey on April 13, 2012, 06:10:39 pmAwesome, that clears up a lot. Thanks for the repy!!Quote from: david77 on April 13, 2012, 06:40:16 pmCool, thanks for the detailed explanations guys, this definitely clears up all my doubts and thoughts. Thanks so much! I'm going to buy a 2709b. I'm going to look into a ESR meter too. Thanks again!!

author: Tube_Dude
author_rank: Regular Contributor
timestamp: April 13, 2012, 08:33:30 pm
content: Quote from: david77 on April 13, 2012, 09:10:16 amHI, David77Actually 66mF is 66000uF and not 6600uF....

author: david77
author_rank: Frequent Contributor
timestamp: April 14, 2012, 01:11:05 am
content: of course.

author: TSX420J
author_rank: Newbie
timestamp: April 15, 2012, 02:26:19 am
content: I ordered the 2709b for 94.50 shipped!!!http://bit.ly/Ioi9gzThanks for the help!!

author: david77
author_rank: Frequent Contributor
timestamp: June 25, 2012, 08:58:29 am
content: In the meantime I got so annoyed by the loud beep of my 2709B I modded it to make it quieter. I just soldered a 3,3k resistor in series with the buzzer. Makes the beep much more tolerable.

author: icon
author_rank: Regular Contributor
timestamp: June 25, 2012, 09:59:57 am
content: Taking a more conservative approach to the annoyingly loud beeper, I stuffed a few layers of tape over it. That quietened it to acceptable levels.John

author: T4P
author_rank: Super Contributor
timestamp: June 25, 2012, 04:03:08 pm
content: Speaking of the beeper on 2709b, the UT61E also beeps every switch move ... But the beeper's pleasant!The D's quite awful compared to the E ...