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Mastech MS5308 LCR meter with ESR measurement - on discount at the moment
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KD0CAC John:

--- 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 .

--- End quote ---

Are you thinking about modding the AC power supply?

--- End quote ---

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:

--- 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 .

--- End quote ---

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:

--- 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 .

--- End quote ---

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.

--- End quote ---


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:
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:
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.

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