Need LCR, seeking advice. - Page 1
Forum section: electronics / general

author: muvideo
author_rank: Frequent Contributor
timestamp: August 28, 2012, 09:53:51 am
content: Hello, I need an LCR meter.Now I have a basic handheld lcr that measures the impedanceand ignores the parasitics.I will use it for ferrite transformers, inductances,and capacitors I use for smps and dc/dc.Also I need it for testing and repair old instrumentationcapacitors. The possibility of biasing would be nice,but it's not absolutely needed.I read with interest Aurora's review of MS5308 andit fits most of the requirements I have.Before buying it I'm curious what kind of old usedinstrumentation can be found with the same or higherspecs at decent price.I've seen some HP 4262/3 but usually are much moreexpensive (unless badly broken).Also there are some Racal Dana 9343 or SR715/20.Can you advice models of good LCR bridges tosearch for on surplus equipment listings?Thank you.

author: jarvis
author_rank: Contributor
timestamp: August 30, 2012, 09:07:57 am
content: http://www.extech.com/instruments/product.asp?catid=56&prodid=692

author: jarvis
author_rank: Contributor
timestamp: August 30, 2012, 09:08:48 am
content: LCR200 is the same chipset solution as MS5308

author: muvideo
author_rank: Frequent Contributor
timestamp: August 30, 2012, 09:59:33 am
content: Thank you for the suggestion, what are the strong points of LCR200 against MS5308?As for my original question, probably I wasnt clear about what I was searching...basically any advice about old LCR meters that can be found from surplus equipmentsellers and that can be good value for money.I dont mind repairing old stuff and having heavy weight big boxes around, if it's worthAnother perspective, say that I find an hp4262/3 or a 4274/5 in decent shape,will they be substantially better than MS5308 (I imagine yes)? In what kind ofmeasurements will they outshine these cheap LCR meters?Will be they repairable or are full of asics?What is an acceptable price to pay for these old glories?ThanksFabio.

author: T4P
author_rank: Super Contributor
timestamp: August 30, 2012, 02:49:07 pm
content: If not, exactly the same.Except that both Mastech and Extech instruments are high quality which ... heck you'll see which one your mind goes for

author: free_electron
author_rank: Super Contributor
timestamp: August 30, 2012, 05:41:58 pm
content: If you are into smps then dc biasing is a must. Especially if you want to understand things like core saturation under dc boas as wel as derating of capacitors.Your only option is hp4263 style machines that do 4 point measurements. For transformers you want option 1. As it can do turn ratio and mutual inductance i believe.Repairing those is not easy. However, most faults are user errors. Blown outputs ( the protection diodes short out ) or the drive amplifer burns out. These machines are a mix of smd and thru hole. Nothing really special or labeled apart from the a/d converter chip. That is an asahi-kasei beast and hard to get. The lcr bridge is actually an hp-yokogawa design made by yokogawa in japan. Most opamps are jrc ( japan radio coroporation ). Nmc3xxx types. Digikey has em. No problem. Bunch of analog switches.Service manual or schematics are not available apart from a block diagram. Repair is a wild-shot approach. Simply replace all chips in a block. Costs you 20$ at most. Begin with chips closest to output and input.The motherboard of an A and B is the same. Only the computer and display assembly is different. Hp gave up on their propritary single line starburst displays and switched to a standard 2*40 lcd in the B version. That requires new computer board. The computer board is almost non repairable as it contains two asics. But then again, i've never seen one that has failed. I've repeaired 3 of these machines so far. Al shot output protection. I am now working on a 4th one i got for myself. This one has a stuck input attenuator. Probable a mux that died.Got it for 200$ off fleabay.As far as performance. I think these outshine by far the wingpangpongs like the mastek etc. The HP machines are vector meters. They use a two channel ADC and digitize voltage and current in sync with each other. The machine analyzes phase and amplitude relation. The adc is a pulse density modulation thing with 24 bit resolution feeding into an asic on the computer board.The adc is actually a reference ADC for sacd disc recorders. It samples at 192 kilohertz. Very strange thing. Made by asahi kasei.

author: T4P
author_rank: Super Contributor
timestamp: August 30, 2012, 06:02:30 pm
content: Just a thing yokogawa had on hand and decided to you know ... they might have wanted really fine resolution i guess? I'm not even sure if it's high resolutionIn any case, your point on wingwangpongs like the mastech is valid because they are good are what they do, well, take crude but more accurate measurements compared to 30$ LCR MetersF_E what do you think of this wingwangpong?http://www.precisegauge.com/index.php?main_page=product_info&cPath=106&products_id=524&zenid=4kl7ji4ilvfouhqau7onuaq7t7

author: muvideo
author_rank: Frequent Contributor
timestamp: August 30, 2012, 07:09:58 pm
content: Free_electron thank youverymuch, there isn't much info aroundfor these devices. I'll stay tuned on HP4263, better if with option01.200USD would be a price that I could risk for, also if the unit wouldneed repair. On ebay forget it, the prices are too high: just now there isone '63A that is scrap metal and the seller doesnt want to go under250USD.What's the difference with HP4274/75?Fabio.

author: free_electron
author_rank: Super Contributor
timestamp: August 30, 2012, 09:25:26 pm
content: Quote from: T4P on August 30, 2012, 06:02:30 pm

author: PA4TIM
author_rank: Super Contributor
timestamp: August 30, 2012, 11:40:59 pm
content: Find an old GR1608 or GR1650, you buy a nice one under 100-150 dollar. They messure LCRG. They read in Cs and Cp together with D ( but you easy calculate ESR from that) Ls and Lp with Q, and G and Rac ( also omplex) and R in DC mode.They have Bias possibilities and you can connect external genertors and external D/Q decades or an external capacitor and measure R + jX.I have both. Aso the Marconi TF1313A is interesting but has tubes.I use them to meaure, besides the usual, loudspeakers, Ri from batteries, ESR, even made DC leakage test fixture. You can measure h-parameters.With two opamps and a scope you can measure BH curves ( find the Tektronix O plugin manual, it has two valves opamps And application notes for this, but just use modern opamps.)I made a saturation tester, is very easy and very handy,The 1608 is 0,1%, the 1650 is 1%, the big difference with all the modern pocket size meters is that the GR are real %, not commercial ones. My bridges are still perfect. ( tested agains standards and VNA measurements)The 1608 can be used with 3 wire measurements. The 1650 to but it is not stated clear in the manualHowever it works fine that way.See my sitewww.pa4tim.nland search for the GR-1650 and GR-1608Probably will a HP4260 also do what you want. That has also bias capabilities. Easy to repair, handy in use. Got one too.

author: muvideo
author_rank: Frequent Contributor
timestamp: September 01, 2012, 06:32:15 am
content: Thank you Fred, that's interesting.Never used a manual bridge, is there any resourceonline where I could find more info and how to's about these?Fabio.

author: PA4TIM
author_rank: Super Contributor
timestamp: September 01, 2012, 03:54:12 pm
content: Hi Fabio,The manuals from GR are downloadable at several sides. Also very intresting are the General Radio Experimenter magazines. If you google them you find them.And every older electronics book about measuring has lots of info about bridges. There are over 20 configurations, weathstone is one of the best know.