Author Topic: Mastech MS5308 LCR meter with ESR measurement - on discount at the moment (Read 152571 times)

KD0CAC John · « **Reply #200 on:** January 23, 2013, 08:07:44 pm »

Quote from: nixxon on January 23, 2013, 08:04:42 pm

Quote from: KD0CAC John on January 23, 2013, 03:45:37 pm
Again after all this I would hope to see a mod be developed , not enough knowledge on my end , but have a new MS5308 .

Are you thinking about modding the AC power supply?

No I was looking to see if anyone was working on a mod , not sure myself if the mod needs to be in the meter / or another power supply ?

nixxon · « **Reply #201 on:** January 23, 2013, 08:08:12 pm »

Quote from: KD0CAC John on January 23, 2013, 07:43:52 pm

I got mine through ebay a couple months ago , from China , I opened mine to check if the neg. wire was moved from the through-hole over to the SMD cap , and it was .
I did not check / or remember the board vs. but will check when I get a chance , will try to post tomorrow .

Are you thinking about the "R16" resistor? User "gfx2006" on Youtube comments to the jwrelectro MS5308 review video that "I measured mine and it's zero resistance between R16 and GND". That is pretty low resistance and probably just as good as soldering the wire to "GND". No mod needed here.

KD0CAC John · « **Reply #202 on:** January 23, 2013, 08:47:09 pm »

Quote from: nixxon on January 23, 2013, 08:08:12 pm

Quote from: KD0CAC John on January 23, 2013, 07:43:52 pm
I got mine through ebay a couple months ago , from China , I opened mine to check if the neg. wire was moved from the through-hole over to the SMD cap , and it was .
I did not check / or remember the board vs. but will check when I get a chance , will try to post tomorrow .

Are you thinking about the "R16" resistor? User "gfx2006" on Youtube comments to the jwrelectro MS5308 review video that "I measured mine and it's zero resistance between R16 and GND". That is pretty low resistance and probably just as good as soldering the wire to "GND". No mod needed here.

I am not sure yet , with what seems to be a couple of related themes in the last few pages , of when using the external PS and the resistance changing / being off ?
And the supplied external PS damaging the meter , so only use the batteries ?
Would to avoid both issues , weather they are related or not ?

nixxon · « **Reply #203 on:** January 31, 2013, 10:24:31 am »

I received my MS5308 yesterday.

The black neg. wire was soldered directly to "GND". The wire is barely reaching the "GND" solder point, though. The tension of the wire is like a guitar string. They must have soldered the connection before mounting the small power supply PCB.

Resistance between bottom side of "R16" and "GND" is measured to 0.0 ohms in relative mode (Fluke 83 V).
Resistance between top side of "R16" and "GND" is likewise measured to 287 ohms.

PCB is labeled "MS5308A(2011.05.06)"

iloveelectronics · « **Reply #204 on:** January 31, 2013, 01:10:40 pm »

Those 2 contacts look way too close to me for direct soldering. I guess that's why some other units (not sure if it was earlier ones or later ones) they decided to solder the ground wire to R16. They should have used a proper connector to begin with though.

Anyway, I've also got news about the power adapter issue directly from the manufacturer (through their sales team). They even showed me what looks like an internal report on the issues (written in Chinese).

To summarize:
1. They are aware of the issues through reports from their customers.
2. Besides the incorrect reading on resistance measurement as shown in John's video review, the power adapter could also potentially fry an IC (they didn't mention which one) and stop the meter from switching on.
3. They acknowledge that it's a design flaw in the power adapter that causes excessive ripples, which leads to the above mentioned problems.
4. The meter functions correctly and within specs otherwise (when on battery power).
5. There's no fix at the moment apart from advising their customers against using the power adapter. For customers with a fried IC they will offer a replacement one with instructions and assistance on how to replace it. The power adapter will no longer be packaged with the meter from now on.
6. They will be working on a redesign and modification in the documentation.
7. After that they will modify all the units that still haven't left the factory.

As a wholesale customer of theirs I will not get any form of compensation apart from some replacement parts if I need them. It sucks. I won't hide it. I received the MS5308's early last week but had been waiting for these official words before I feel comfortable selling, and I must say I'm quite disappointed myself. I guess if I really wanted to pursue it further I could but I don't think I'm going to as I believe the meter is still a good value otherwise, plus I don't really want to ruin the working relationship with Mastech.

Now that their position is clear I will start selling them soon, although I will most likely sell at a slightly lower price than I initially hoped for, and with clear warning to any potential buyer too.

KD0CAC John · « **Reply #205 on:** January 31, 2013, 03:13:02 pm »

Good to hear some details from them .
Seems to confirm that the issue is with the PS only " excessive ripples " .
Not being into electrical design , just hobby , wouldn't using a filter cap added to the PS solve this ?
Besides just using a good , maybe laptop supply - reduced to the correct voltage ?

SeanB · « **Reply #206 on:** January 31, 2013, 03:51:08 pm »

Not ripple on the voltage, but too much HF noise riding on top of a mains frequency waveform injected into the power rails. Basically they need a power supply with a grounded secondary side.

nixxon · « **Reply #207 on:** January 31, 2013, 05:02:01 pm »

It should not be a big deal to find another 12V DC power supply from some old equipment. I will check the output quality first, of course. If it is a linear type, there should not be high frequency noise anyhow.

Even so, I will check out if a .47 uF X2 capacitor I found will reduce the noise from the Mastech power supply...

bingo600 · « **Reply #208 on:** January 31, 2013, 05:23:28 pm »

I have a Mastech meter (from summer 2012) , so i'm prob affected by the problem PSU.

Now i have several 12v wall-wart switchers and also an old 12v ironcore wall-wart.

My question is ...

How close to the 12v do i need to be ?
As in how well regulated/clean does the DC need to be ?

The Iron-core prob puts out 12+ volts ?

Is there a regulator inside the meter ?

Or does the supplied 12v need to be 100% clean , i have some LM340-12 in TO220.
But would like to avoid an "external" box if possible

How many mA does it need to deliver ?

TIA
Bingo.

nixxon · « **Reply #209 on:** January 31, 2013, 07:48:43 pm »

It draws ~15 mA w/o backlight, according to the review video. ~~With backlight, it was ~30 mV IIRC.~~ EDIT: I don't know the current draw with the backlight on.

I have read that 9 volts is the absolute minimum for the meter to operate.

BTW: The meter can handle a 75 cm drop from a table down onto a ceramic-like tiled floor. It makes a horrific sound as the unit hits the floor, though.

tcdrennen · « **Reply #210 on:** February 07, 2013, 01:25:35 am »

Hey people, just joined the forum.

We're very interested in the MasTech RCL meter - we can live with and/or fix the power problem

but our requirements are that the meter will have to be on our calibration schedule.

Has anyone looked into calibration requirements for this meter? Is there a service guide/manual? Is there a stated calibration interval?

We're an EMS and have plenty of PM3504 and QuadTech LCRs but they're a bit pricey

; this would be a perfect IQC solution for some coils we need to screen at receiving, but we';; need calibration.

We may buy a couple for in house use anyway - I will get back to you ASAP on that.

Nice forum - 'll be poking around a bit

helion · « **Reply #211 on:** February 13, 2013, 08:04:35 pm »

review on Youtube might help you I guess.

nixxon · « **Reply #212 on:** February 15, 2013, 09:26:46 pm »

That video is nice, but I don't recall anything regarding instrument calibration, other than the recessed button calibration open/short auto stuff.

These guys claim to have the know-how, though: http://www.microprecision.com/instrument/MASTECH-MS5308.html

robrenz · « **Reply #213 on:** February 15, 2013, 09:51:59 pm »

Quote from: nixxon on February 15, 2013, 09:26:46 pm

These guys claim to have the know-how, though: http://www.microprecision.com/instrument/MASTECH-MS5308.html

That appears to be one of those places that will claim to be an expert on calibrating anything you can google. Not saying they are not reputable but you get a canned capability statement on just about any instrument. Ask for a quote and see what you get. I can almost guarantee it will be a multiple of the price of the MS5308.

tcdrennen · « **Reply #214 on:** February 16, 2013, 12:11:42 am »

Thanks for the updates - our local cal lab says they can calbrate it for us, so we should be good to go

I've ordered one for our department and have recommended it to our vendor so they can pre-screen the coils.

PA4TIM · « **Reply #215 on:** February 16, 2013, 07:17:43 am »

Let us hear the outcome of the calibration. They dan not adjust s as far as I know so they can only give you a certificate that tells how much it is off. They only eed detailed specs for that, and without those thy can not verify it but only tell you the deviation towards a tracable standard. Over a year after the second calibration you know if it was a good choise. If it is still the same amount off you are lucky, if it has drifted a lot you have to go back in time and check if customers could ave problems because your meter went wrong.

Do not use the powersupply, it kills this piece off junk. For a company I would have bought the IET e-5000, it can be bought calibrated ( IET or NIST) and you have the pricediverence payed back within a year because it can be used on a external powersupply or a 9 V battery instead of a bunch of batteries to get 12V ( it does not run on 9V allthough people say it uses the same chipset, it also has a lower accuracy as the IET)

tcdrennen · « **Reply #216 on:** February 16, 2013, 08:20:27 am »

Thanks for the headship; I'll look at the IET first - though the video was pretty good on the MasTech.

I was aware of the power brick issue - we do have a box of wall warts that I was thinking of using (12V, 9V, 5V; collected over the years in the dept from various projects.)

The advice is much appreciated - we may get the 5308 just to see how it holds up, but i will check the IET unit.

SeanB · « **Reply #217 on:** February 16, 2013, 08:33:08 am »

Got mine yesterday, and broke the power supply open to get the cable out. will use it for something else after attaching a 3 pin IEC socket and earthing the secondary ( that is the problem, interwinding capacitance leads to switching hash on the output, and it has no isolation barrier capacitor to reduce it or a interwinding shield) along with a small LC filter as well, all in a larger case ( old one did not survive the opening with gentle persuasion using a claw hammer).

Took it and ran it using a power supply and a 7812 to regulate the voltage ( 7812 will be in the new power brick when I assemble it, epoxy is busy curing that holds the transformer down at the moment). It works well using the external power.

Fraser · « **Reply #218 on:** February 17, 2013, 12:19:53 pm »

SeanB,

Thanks for this. I have not used my unit on an external power supply yet. The provided unit will be going in my 'spare parts only' bin. I have some decent AOR linear 1A power supplies that use a quality regulator circuit (V set and I limit adjustable). I will use one of those if needed.

Fraser

iloveelectronics · « **Reply #219 on:** February 17, 2013, 12:46:51 pm »

Guys, DO NOT USE THE POWER ADAPTER that comes with the unit! I just had one buyer report to me that his unit failed after using it a few times

ddavidebor · « **Reply #220 on:** February 17, 2013, 01:16:43 pm »

I don't understand... Is the power adapter broken or the meter don't accept any power adapter?

iloveelectronics · « **Reply #221 on:** February 17, 2013, 01:24:02 pm »

Quote from: ddavidebor on February 17, 2013, 01:16:43 pm

I don't understand... Is the power adapter broken or the meter don't accept any power adapter?

The power adapter that comes with the MS5308 is faulty. Mastech knows it and they will not be supplying the adapter in their newer units. A proper 12V DC power supply would do the job fine though.

SeanB · « **Reply #222 on:** February 17, 2013, 02:04:42 pm »

The power adaptor that comes with the unit is a OHL unit with no interwinding shield, thus this places switching transients on the supply it puts out. This then is transferred to the meter and if there is a large capacitance from the meter to ground this blows the input circuitry by exceeding the common mode range of the unit ( 30V absolute max peak).

If mister designer had put the class Y capacitor across the isolation barrier and added an interwinding shield winding then this would be a non issue, even with a 2 pin supply. A 3 pin supply with the output grounded would have been better though.

ddavidebor · « **Reply #223 on:** February 17, 2013, 03:46:14 pm »

Incredible, it's possible to fail even in a ac-dc wall adapter.

Fraser · « **Reply #224 on:** February 17, 2013, 03:57:14 pm »

OK, I am going to show my ignorance here

In my working life I see many SMPSU blocks that have "ITE Use only" printed on them. This means 'Information Technology Use Only'. I took this to indicate that the output is noisy and not suitable for sensitive equipment like audio kit etc. However, computers don't like noisy power supplies either. With EMC rules it is also important to design low noise power supplies so my theory looks to be wrong ?

Can anyone enlighten me as to the true reason for "ITE Use only" on SMPSU blocks ?

Fraser


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Author Topic: Mastech MS5308 LCR meter with ESR measurement - on discount at the moment (Read 152571 times)

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