DER DE-5000 LCR Meter Problem (Defective?) - Page 1
Forum section: electronics / testgear

author: Legion
author_rank: Frequent Contributor
timestamp: April 04, 2014, 06:38:31 pm
content: Just got this today from Japan. Unfortunately the unit appears to be DOA.I put in the 9V battery it came with and it wouldn't turn on. I checked the battery and it was really hot, so I removed it. I verified that the battery was inserted with the correct polarity. I also tried a different 9V battery but the unit still won't power on.Anyone else have this problem?

author: Legion
author_rank: Frequent Contributor
timestamp: April 04, 2014, 06:43:43 pm
content: If I put in the 9V battery it comes with the battery immediately starts heating up. If I put in my own battery the unit still won't power on, however the battery doesn't get hot.Scratch that. My battery heats up too. Just more slowly.

author: Fraser
author_rank: Super Contributor
timestamp: April 04, 2014, 06:51:38 pm
content: Internal short ....DOAChoice is whether to return it, or open it up and look for the short. Likely easily found and a solder bridge/splash. Unit could not have been calibrated in that state though, so if these do undergo calibration at time of manufacture, send it back for a replacement.

author: Legion
author_rank: Frequent Contributor
timestamp: April 04, 2014, 06:56:40 pm
content: Quote from: Aurora on April 04, 2014, 06:51:38 pmNot sure about calibration. The PCB is pretty bare, very small SMD components. I only work with through hole components so I guess it's gotta be returned.

author: kripton2035
author_rank: Super Contributor
timestamp: April 04, 2014, 07:28:52 pm
content: well if you paid with paypal it should be free to return it ?sorry to hear one bad story about this meter, anyway it's the first...and you need to see how the seller will deal with it.

author: Legion
author_rank: Frequent Contributor
timestamp: April 04, 2014, 09:19:10 pm
content: Quote from: kripton2035 on April 04, 2014, 07:28:52 pmSeller seems nice so I don't anticipate any problems. Not sure I want to get another one though. If I tried to exchange it I'd be looking at 6 weeks before I'd get the replacement. If there was an electronics store in Toronto I'd just go get a different one.

author: Rory
author_rank: Frequent Contributor
timestamp: April 04, 2014, 09:23:51 pm
content: It is a very good meter. When you get a working one, you will be glad you did.

author: markce
author_rank: Regular Contributor
timestamp: April 04, 2014, 10:43:54 pm
content: Give the seller a chance to correct this. It's a really nice meter.Don't try to repair a new one, there is not much in it, didn't see a schematic either.

author: Legion
author_rank: Frequent Contributor
timestamp: April 05, 2014, 03:37:21 am
content: Returning the defective unit to the seller. Ordered a replacement from a different seller to reduce the wait time. This one comes with all the accessories.

author: kripton2035
author_rank: Super Contributor
timestamp: April 05, 2014, 07:39:22 am
content: mine took 10 days to come from japan to france. I find 6 weeks excessive !

author: KedasProbe
author_rank: Frequent Contributor
timestamp: April 05, 2014, 08:49:42 am
content: Just open it, there is no void warranty sticker, and it's possible you can see the problem easily.It doesn't mean it isn't calibrated, it would be strange if it passes the calibration without calibration.With some luck it's just the soldering wires of the battery to the PCB.edit: also check the polarity of the soldering to the PCB

author: eurofox
author_rank: Unknown
timestamp: April 05, 2014, 09:07:41 am
content: It is a very nice, precise and reliable instrument.I got my unit from Japan as well from a very kind Japanese ebayer and arrive in +/- 2 weeks, in my country it always spend more time in custom clearance the the real shipping time.eurofox

author: markce
author_rank: Regular Contributor
timestamp: April 05, 2014, 09:03:00 pm
content: Bought mine from Japan as well.It's a huge positive difference in delivery speed and communication, compared to most sellers in China.

author: sarm
author_rank: Contributor
timestamp: April 05, 2014, 09:54:43 pm
content: Can you please share from what store just for research purposes.

author: eurofox
author_rank: Unknown
timestamp: April 05, 2014, 09:58:02 pm
content: Quote from: sarm on April 05, 2014, 09:54:43 pmhttp://www.ebay.com/itm/NEW-DER-EE-DE-5000-High-Accuracy-Handheld-LCR-Meter-w-TL-21-TL-22-TL-23-IET-/271344250865?pt=LH_DefaultDomain_0&hash=item3f2d60aff1

author: sarm
author_rank: Contributor
timestamp: April 05, 2014, 10:01:09 pm
content: Quote from: eurofox on April 05, 2014, 09:58:02 pmThank you eurofox.

author: qf
author_rank: Newbie
timestamp: March 04, 2015, 02:25:30 pm
content: I got a unit from Japan via ebay and this is what it does when I put the battery in. Spoiler, yes it gets hot. Unit is DOA. Seller is sending a replacement without need for return of old unit. Oh and mine also made a bit of an unhappy electronics odor, nothing too pungent but it was present after leaving the battery in for a few minutes initially.http://qfrog.smugmug.com/Other/lookeylou/1892821_4CJNJx#!i=3907794444&k=bgPqm3wHas anybody tried powering up a DOA unit via the 9v center positive port on the side of the unit? If the port works and the unit powers up I think this could explain the suggestion that the unit was not calibrated in this state. It could have been calibrated while powered via the port.

author: Fraser
author_rank: Super Contributor
timestamp: March 04, 2015, 05:05:14 pm
content: I have bought many pieces of faulty electronics that display the symptoms that you describe. The good news is that in most cases the fault is a solder bridge on the supply rail from the battery to the regulators or DC-DC converter. The smell f burnt electronics is normally coming from the a diode that sits in series with the battery +ve.Popping the covers on the unit and a visual inspection will likely find a toasted SMD diode and a solder bridge to 0V somewhere on the rail that it feeds.Equipment is normally calibrated on test jigs or through an external power socket, not through the battery terminals. The external power input can be a different supply path to that of the battery.Pop the case and take some pictures. I am sure we would all love to see what has gone wrong inside.Aurora

author: qf
author_rank: Newbie
timestamp: March 04, 2015, 05:50:32 pm
content: Ok, I'll post pics tonight when I get home. I want to try powering up the unit through the port on the side too. Going to have to venture out to the garage to see if I have wall wart with a compatible connector at 9v DC center positive. Failing that I can always solder a couple of wires directly to the PCB for direct connection to a 9v wall wart.

author: qf
author_rank: Newbie
timestamp: March 05, 2015, 01:10:49 am
content: I have signs of operation! I started probing the components near the power input when it appeared that the positive and negative contacts were shorted. I removed Diode #5 which was reading 0.2 ohms in both directions. The other similarly sized/shaped/marked diodes were reading very differently. Now when I press power the unit beeps and the display reads. So I have signs of operation vs before I had nothing but a hot 9v battery and a dead LCR meter.I presume that I should replace diode #5, but I'm not really familiar with this type of device. What function does Diode #5 serve? Is it input polarity protection? Can anybody suggest what terms I should use to find this thing at digikey or mouser or other suppliers? Thanks!http://qfrog.smugmug.com/Other/lookeylou/i-s5gXwdT/0/O/WP_20150304_003.jpg

author: radhaz
author_rank: Regular Contributor
timestamp: March 05, 2015, 01:28:00 am
content: Looks like it's wired across the battery connector, so probably reverse polarity protection.Here's a possible schematic of the circuit:https://www.eevblog.com/forum/testgear/ms-5308-power-supply-issues/msg189878/#msg189878

author: z01z
author_rank: Regular Contributor
timestamp: March 05, 2015, 08:31:02 am
content: It's a very strange protection. Once the battery is connected with reverse polarity, that diode will surely fry.If it always go short, then is serves its purpose.Looks like I'll have to be careful when changing batteries...As for the type, I'd guess 1N4148.

author: Ericho
author_rank: Regular Contributor
timestamp: March 05, 2015, 12:13:01 pm
content: Looks like a small signal diode, indeed a 4148 / 914I would put a 4001 in there, Either a smd version or bodge a leaded one over the wires or battery terminals.Whatever you got in the bin, at least you can safely test the meter after this.I'm going to open mine and put a decent protection diode in there