Author Topic: Multimeter model for computer tests and repair, up to $40 (Read 7439 times)

grevan · « **on:** June 29, 2016, 02:14:33 pm »

Hi guys,
i´m not a professional, i just want to test and/or fix some of my old computers motherboards, psu, etc.
Is there a cheap, let´s say, up to $40 multimeter, that is reliable?
Thank you very much for any assistance.

MosherIV · « **Reply #1 on:** June 29, 2016, 02:26:19 pm »

It is a bit old now but look at this :

Make your own mind up as to which one you think is good (too many people having arguments about which meter is better).

Someone else to check out is the mjlorton youtube channel for multimeter reviews/tear downs.

Personally, I would advise you to raise your budget to $100(US that is) and get a quality meter.
A quality meter will server you for life.

(Also, try the Test Equipment forum - much more detailed discussion on meters and oh so many meter wars

https://www.eevblog.com/forum/testgear

grevan · « **Reply #2 on:** June 29, 2016, 02:39:20 pm »

Thank you very much, i´ll take a look at these resources.

MosherIV · « **Reply #3 on:** June 29, 2016, 03:10:55 pm »

Some more info for you :

Amprobe is a company that is in the Fluke group of companies. Each has their own design groups but the general consensus is that Amprobe have similar quality and safety as Fluke.

Take a look at the Brymen that EEVBlog offers, it will be above the budget you initially set. No idea how you go about buying one - I guess you look around the EEVBlog web site.

Fluke do a budget range of meters (look up Fluke 15B+ or 17B+) but again above your initial budget. Meant for the Chinese/Indian market, available through ebay or amazon but warranty only valid in China/India region (it is Fluke - if it works out of the box - you should be good).
Very popular with the hobbyists.

HP = Agilent = Keysight
Big rivals to Fluke. They seem to be better value than the equivalent Fluke (eg the U1232a competes with the Fluke 114/115 but you get more for your money). They certainly have the same quality and safety as Fluke and HP have a longer test/instrumentation tradition.
FYI - if you are looking for an electronics DMM - the Fluke 110 series and the Keysight U123x range are really for electricians, they lack mV and uA ranges. (I have the Keysight U1232a, pretty good but 1. auto ranging is annoyingly slow and 2. Temp does not work even though it is on the selector but it does say in the manual you need to buy the additional temp adapter)

Stuartambient · « **Reply #4 on:** June 29, 2016, 04:13:22 pm »

I bought an Amprobe 5xp a few years back and it was about $60 at the time. It's okay basic, accurate and reliable. I will mention it does not have capacitance measuring. That would be an important function for fixing motherboards among other things. I think if you can bump up your budget some get something that is reliable first. A flaky mm could even be dangerous by giving you wrong readings. Also the capacitance is another needed feature unless you have it with another device. Standalone cap meters are available. Just nice to have it in one package.

ez24 · « **Reply #5 on:** June 29, 2016, 04:25:31 pm »

Quote

Take a look at the Brymen that EEVBlog offers, it will be above the budget you initially set. No idea how you go about buying one - I guess you look around the EEVBlog web site.

I have no idea what is available in Brazil. Can you get anything that Amazon sells in the US? There is a member here who sells Brymen in South America.

MosherIV · « **Reply #6 on:** June 29, 2016, 04:33:03 pm »

I am not sure whether the capacitance feature will be much use for fixing motherboards.

If you measure bad capacitors, they show the correct value.
Bad capacitors can be found using Equivalent Series Resistance (ESR). You can get special meters for this.
A proper LCR bridge will measure the ac impedance, I forget which parameter it is but a LCR bridge gives a parameter which can be found on the data sheets which is a better measure of the health of a capacitor.

Measuring Capacitance is a nice to have, it can be pretty inaccurate anyway.
Temperature measurement is more useful.

janoc · « **Reply #7 on:** June 29, 2016, 04:43:48 pm »

Quote from: Stuartambient on June 29, 2016, 04:13:22 pm

I bought an Amprobe 5xp a few years back and it was about $60 at the time. It's okay basic, accurate and reliable. I will mention it does not have capacitance measuring. That would be an important function for fixing motherboards among other things. I think if you can bump up your budget some get something that is reliable first. A flaky mm could even be dangerous by giving you wrong readings. Also the capacitance is another needed feature unless you have it with another device. Standalone cap meters are available. Just nice to have it in one package.

Capacitance measuring on a cheap meter is almost completely useless for troubleshooting issues on motherboards. It is not very accurate and measures only capacitance, not ESR which is much more important. Don't use that as a decision criteria.

Especially the cheap and crappy meters have both capacitance and inductance ranges, but very inaccurate, often with no relative measurement (so no way to zero out the effect of the test leads) and usually unusable ranges (like 20mH-20H for inductance - good maybe for checking motor windings but little else). Better go elsewhere, this is mostly an unusable gimmick on sub $100 meters.

Farthermore, computer motherboards use DC-DC converters (switching supplies) for almost everything. If you want to detect a bad cap you need to measure ESR not capacitance - even a dried out capacitor may still show in-spec capacitance (-20/+80% tolerances are common!) but has sky high ESR that breaks the circuit.

You better get an ESR meter or an RLC meter which can measure ESR as well (i.e. not a cheap $40 piece of junk or one of those little universal part testers). Moreover, an ESR meter allows testing caps in circuit without having to desolder them - something you cannot do with a simple capacitance meter.

I also second recommendation for the Brymen meter Dave is selling in his webshop on the eevblog.com. I have one and in that $100 price category it is a very good bang for buck. Simple to use, accurate and built like a tank. Oh and you support Eevblog too - a win win situation.

Watth · « **Reply #8 on:** June 29, 2016, 05:26:31 pm »

I have the AM-500. Auto-range, µA, etc. . It's in you price range and it seems avalaible in Brazil: http://www.newark.com/pt-BR/amprobe-instruments/am-500/multimeter-digital-auto-ranging/dp/78T5757

ebclr · « **Reply #9 on:** June 29, 2016, 06:59:20 pm »

In Brazil ( brasil) check this guys

http://www.loadingpower.com.br/

TheAmmoniacal · « **Reply #10 on:** June 29, 2016, 07:47:12 pm »

http://full-parts.com/digital-multimeter-sanwa-cd770.html

mtdoc · « **Reply #11 on:** June 30, 2016, 07:20:55 am »

IMHO you can't do better than this meter for under $40.

Review:

grevan · « **Reply #12 on:** June 30, 2016, 02:32:30 pm »

THanks for the excelent tips!
I live in Brazil, but i can buy things on ebay, it takes time to arrive, but it works most of the time.

Stuartambient · « **Reply #13 on:** June 30, 2016, 02:38:10 pm »

Quote from: grevan on June 30, 2016, 02:32:30 pm

THanks for the excelent tips!

All your links are dead. Maybe just bad formatting.

grevan · « **Reply #14 on:** June 30, 2016, 02:43:47 pm »

It´s a problem with the "ebay" insert link button, better alert the site administrator. I´ll fix that. Thanks.

MosherIV · « **Reply #15 on:** June 30, 2016, 03:09:48 pm »

Hi again

"As i understand so far, i must have a multimeter and an ESR meter to deal with capacitors, right?"
Yes, if you want to diagnose bad capacitors you will need the ESR meter as well.

Please be careful with ALL these cheap meters. Avoid measuring live mains voltage with any of them.
These cheap ones really skimp on input protection.

I do not have an ESR meter (yet, I have one of those transistor testers in the post)
so I do not have an opinion on them.

Good luck and enjoy

retiredcaps · « **Reply #16 on:** June 30, 2016, 03:40:12 pm »

If you want to learn more about motherboard and PSU repair at a component level, check out

badcaps.net/forum

http://badcaps.net/forum/forumdisplay.php?f=6

http://badcaps.net/forum/forumdisplay.php?f=32

janoc · « **Reply #17 on:** June 30, 2016, 03:54:53 pm »

Quote from: grevan on June 30, 2016, 02:32:30 pm

ESR Meters:
- MESR100 V2 http://www.ebay.com/itm/191906258579?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
- M6013 http://www.ebay.com/itm/221960474126?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
- MK328 http://www.ebay.com/itm/171927184554?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Careful, only the first one (MESR-100) is actually an ESR meter. I have an older version of it in a different case, it is okay-ish but not great. Well, you get what you pay for.

The M6013 is a simple capacitance meter that doesn't measure ESR (i.e. useless). The MK328 is one of those Chinese clones of the universal part tester, repackaged into a case (they normally ship as a bare PCB without case. something like this:
http://www.ebay.com/itm/Mega328-Transistor-Tester-Diode-Triode-Capacitance-ESR-Meter-MOS-PNP-NPN-L-C-R-/221869224752 ).

That one can sorta measure ESR, but not in circuit, so it is not all that useful. Also it is fairly inaccurate - it is a tester for quick go/no go check and getting a ballpark value for the component, not a real lab instrument. That said, if you are interested in electronics, it is good to have one of these on the bench - quickly checking transistors pinouts or a resistor value is much faster with it than with a multimeter. However, I would rather recommend one of the "naked" ones without case and leads but with a ZIF socket. That is a lot more useful than fiddling with leads. Also the bare PCB usually has several pads where you can press an SMD component to test it - that's very hard to do with the alligator clip leads.

If you want an ESR meter, you need something like this:
http://www.ebay.com/itm/Portable-Digital-Capacitor-ESR-Tester-Internal-Resistance-Meter-Test-In-Circuit-/322034893012 (probably the same as the MESR-100, only different case)

or

http://www.ebay.com/itm/AnaTek-Blue-ESR-Low-Ohms-Meter-Complete-Kit-for-Assembly-BESR-Kit-/181171316406
The Anatek is actually using the same circuit as the one Dave is demonstrating in one of his videos - that is a proven good meter.

The multimeters you have posted are almost universally junkers, pretty much all of them are going to be dangerous if used anywhere near mains (e.g. troubleshooting a computer power supply). Vichy & Victor products are I believe the same manufacturer, just different branding and known for mediocre quality. I would strongly recommend you to not skimp on money here and go for at least a $100 brand name meter (Amprobe, Fluke, Brymen, BK Precision, some Extechs .. ) here. A good meter will last you decades.

It is your health at stake - the meter is often the only thing between you and the mains voltage, you want it to be designed properly to protect you should anything go wrong. The meters you have posted are perhaps OK for someone fixing their car or a beginner playing around with an Arduino but not really anything more. Multimeter is not a good place to save money on.

ez24 · « **Reply #18 on:** June 30, 2016, 08:08:09 pm »

Here is a spreadsheet on meters

https://www.eevblog.com/forum/testgear/multimeter-spreadsheet/

The first thing I look for is it does NOT use 9v batteries because they are expensive

Try searching Amazon and look at reviews.

For ESR:

https://www.eevblog.com/forum/testgear/multimeter-spreadsheet/

This is the one I wish I had

https://www.amazon.com/-5000-Handheld-LCR-Meter-accessories/dp/B00S298KJO/ref=sr_1_9?ie=UTF8&qid=1467317126&sr=8-9&keywords=esr+meter

I believe it is the gold standard

MosherIV · « **Reply #19 on:** July 03, 2016, 04:11:40 pm »

Hi

Now that I got the transistor/esr tester, I thought I should show you what I said about bad caps showing correct value:

So the first picture show the good cap. ESR is coming out at less than 1ohms and reads 6uF a little high but still close eniugh to the 4.7uF

The last 2nd picture show a bad cap, reads 4.1uF, ESR is well 18ohm

janoc · « **Reply #20 on:** July 03, 2016, 09:46:35 pm »

Yup, I have a few caps like that too. Shows that a capacitance meter is useless for troubleshooting these things unless it measures ESR too (most don't).

BTW, apparently some of these testers actually can measure ESR in circuit using the leads 1 and 3 if you hold down the test button for longer. Some firmwares will show a menu with a few extra options there. Mine doesn't have it, but perhaps yours is newer since it has the graphic LCD (I have the old style one with 2 line text LCD).


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Author Topic: Multimeter model for computer tests and repair, up to $40 (Read 7439 times)

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