No.128 - Agilent U1731A LCR Meter Repair

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This Agilent U1731A LCR meter isn't powering up properly and seems to have multiple faults.
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[@TheEmbeddedHobbyist]

This does look like a case of maybe a charged up cap being connected to the input. the worst I've had with zebra strips is the plating on the glass being etched away due to moisture ingress. Don't seem to take much to remove the few atoms of metal on the glass.

[@IanScottJohnston]

Ahhh, yes of course!.....probably some large electrolytic.

[@TheBreadboardca]

I have yet to see a failed repair from you Ian, well done yet again, keep them coming

[@IanScottJohnston]

Cheers Peter!......there is a Fluke 8846A that I posted a part 1 for.....really need to get back to that nightmare soon!

[@robharley9838]

Nice sleuthing Ian! I thought the same thing as some others. Sooo easy to forget to discharge a cap under test and knacker the "front end". Surprising no resistors popped. Love your skills. Thanks for the content! - jrh

[@radio-ged4626]

I really must look out for more faulty test equipment for sale. Nice little fix on this LCR meter.

[@IanScottJohnston]

EBay prices are high so it’s quite tough and expensive. Luckily, I have a local contact outside of EBay.

[@raymiller5738]

You might find that BJT transistors used with collector-base junction as a diode may also be for very low leakage, or couse limited by the max base current.

[@SkySky-zr3bt]

I learn SO MUCH from this video! Huge thanks for great video! Cheers

[@brendanbarbour8568]

Great detective work again Ian…shows how handy an IR camera can be in these situations would the replacement battery cover be a candidate for the 3D printer..?

[@ulwur]

Nice work!

[@ixamraxi]

I prefer a pencil eraser for the first clean above ipa. Fiberglass pen seems too harsh for me. Great repair though, appreciate you showing your thought process.

[@IanScottJohnston]

Provided you are really light to touch with the fibreglass pen it's pretty good. Saying that, there are different grades of the pens, the red coloured one is not the lightest, maybe I'll try the nylon ones next time. Red = fibreglass / soft Yellow = brass / medium Black = steel / hard Blue = nylon soft Green = nylon hard

[@ixamraxi]

@@IanScottJohnston Honestly didn't know there were different hardnesses on fiberglass pens, thats good to know! The auto store only sells one, lol.

[@joelkist6493]

Nice work! I very much enjoy watching your video's.

[@midgoog2]

Ian, maybe a charged capacitor was plugged into the unit possibly taking out those components. Cheers Eric

[@IanScottJohnston]

Yep, that’s the common opinion of some others here in the comments also…….and I agree.

[@eded8045]

you should have as many subs as that Aussie with the big knife by now

[@IanScottJohnston]

Thankfully it is video views that count, and I get regular views on each video up in the numbers where some channels have 100k subs.

[@Evergreen64]

I guessed the zebra strip for the first failure. But boy, the rest really led a merry chase!

[@daveturner5305]

Might have been interesting to see a before and after IR camera picture.

[@pcwrangler09]

I find erasers work great on gold contacts without removing the plating.

[@temyraverdana6421]

You are a big magician!

[@Richardincancale]

20:28 ‘…as a bit of a recap…’!!! And a bit of a re-FET!!

[@GadgetUK164]

Excellent work =D

[@sudhirpandit2829]

very useful video, thanks

[@stoptheirlies]

Well done Ian, Ian, how do you go about finding SMD component codes, I have a hell of a time with it. Bob

[@IanScottJohnston]

Google SMD COOKBOOK, there are a couple sites near the top.

[@stoptheirlies]

@@IanScottJohnston Thank you Ian, did you mean cookbook or codebook?

[@breedj1]

Nice repair. Don't you have the macrolens for that camera? I can recomment it. It is very usefull. You can get much closer and see individual smd components with it.

[@IanScottJohnston]

Yes, I should really get it.

[@theelmonk]

I have a 1732B which looks very similar apart from being orange. I think I got it cheap because it had been obsoleted by the 1732C. They seem to have made a lot of revisions and I think they're actually rebranded chinese, not really Agilent. Does anyone know the history ? Good to see you test it before reassembly. I get very impatient with people who seem to completely reassemble things rather than testing in stages.

[@sebastian_harnisch]

The meter looks similar to BK precision (that is a rebranded asian product, afaik), but it is quite different. Reverse order of terminals, no 4 wire, different display, different number of counts etc, mechanical on/off switch etc. All that doesn't mean that it isn't a chinese design, but at least I haven't seen an identical chinese meter yet.

[@windshield11]

Pretty sure they use the same family of Taiwanese LCR chips. You can see the DE-5000 over at the end of the video. Cool little things.

[@eded8045]

nice job....thanks for not filming the soldering/de soldering parts

[@IanScottJohnston]

Sometimes I do, sometimes I don’t. It just depends on how interesting I think it may be.

[@davidv1289]

Nice repair! I'm thinking TEH is right, a charged electrolytic capacitor connected to the input. Did you check the capacitor removed from the board? Always like to know if it was the crapacitor 😊 Regards, David

[@IanScottJohnston]

No, I chucked it already.

[@IanScottJohnston]

Found it!......40uF, ESR 4ohms (it's a 47uF 25V cap)

[@gordonemery6949]

Just subscribed thanks for the vid 👍

[@IanScottJohnston]

Cheers!

[@KB1UIF]

Hi, Nice video and fix. Where do you find the cross reference for the component codes? I have not found a reliable source to be able to get a translation of these codes. Thanks.

[@IanScottJohnston]

Search for SMD Cookbook and you’ll find a few.

[@KB1UIF]

@@IanScottJohnston Thank you. 👍

[@mariomionskowski6223]

Not easy but will done.

[@worroSfOretsevraH]

That huge Wima cap in there tho..

[@fredflintstone1]

Dirty Zebras were a problem with fluke meters 🙂

[@IanScottJohnston]

Ebay are making a killing selling 'repair kits' on Ebay for them......am guessing a good clean would help!

[@fredflintstone1]

Who's that funny guy in a hat 🙂