how repairable is an 5700?

[niner_007]

Considering one, are there any unobtanium pieces inside it that could not be bodged or replaced, like the U180 in the 3458A? From a long term ownership perspective.

And what makes a 5700 an 5720, is it only the reference (have read TiN's guides and repairs), or is it more involved?

[TiN]

Well, everything is repairable, depends on amount of dedication. I've fixed many 57** boards before, mostly they are easily repairable. More advanced repairs would be related to hybrid thin-film resistor networks and ceramic modules (which are fragile, and there are number of them). Also 5720A is evolution over 5700A and have multiple different changes on every board, its NOT just reference. Most of modifications are for reliability improvement and high-voltage AC performance improvement.  Join IRC, I can answer specific questions if you have any.

From long-term ownership perspective, sometimes you can buy 5700A for few k$ (units for 5-8k$ quite easy to buy with patience). But I'd say account for 3-5k$ spare parts / donor cards / relays / misc support hardware budget. My first unit I've build up to full 5720A grade hardware ended up in 12k$ mark, second 5720A was about 6k$. Both of these took me ~3 years to build (from random parts). I also have about 60% of "donor" boards now to build 3rd 5700A. Would I do it again, given the choice? Yes, I've learned crazy lots of cool stuff during this project.

It is also cheaper in the end to maintain all my Keithleys and Keysights in-house, with own calibrators rig and automation. You still do need perform full calibration of calibrator (not just do artifact cal and be happy ). And you can also send 5720A to Fluke for calibration (about $5k ballpark) to get your lab for nice and traceable DCV, DCI, ACV, ACI and resistance.

If you just want unit that works and need minor repairs, then aim for 10k-ish unit in good condition, if we talking eBay and such. Sometimes better deals also pop up, but you gotta have cash right away. Few of my friends got complete or almost complete 5700A for under 5k$.

You can also hunt down more budget-friendly MFCs such as Datron 4708, 4808, 4000. They are harder to maintain and calibrate, but have some different capabilities vs Fluke. Or if you really want budget and don't mind lot of operator work during use then get a tandem 5440B+5200A+5450A.

[e61_phil]

With 5440B + 5200A + 5450A you only cover DCV, ACV and resistance. For DCI and ACI you need at least a transconductance amplifier on top.

I don't know if calibration of a 5720A is more expensive, but calibration of the 5730A costs 2k4 at Fluke in germany.

[MadTux]

5440B, much more user repairable (just the 5700 VFD looks like a nightmare to replace) and I like the 1box-1function principle, not the box stuffed with ACDC-voltage/resistance/AC/DC-current. Makes troubleshooting/repair and calibration/adjustment more easy to do.

Put 5200A and 5450A on top, if you need accurate resistance/AC-voltage as well.

[jfphp]

Are the 5700 VFD (left and right) still available ? Did anybody propose a replacement ? (With a friend we built a drop in replacement for the 5440B).

[niner_007]

The 5700 on ebay start with something like 14K-16K, 5720 start from 25K Seems a but high. I found one 5700 that was 12K which I though was low, but apparently not based on TiN. It was calibrated in “good” condition.

[niner_007]

5440B, much more user repairable (just the 5700 VFD looks like a nightmare to replace) and I like the 1box-1function principle, not the box stuffed with ACDC-voltage/resistance/AC/DC-current. Makes troubleshooting/repair and calibration/adjustment more easy to do.

Put 5200A and 5450A on top, if you need accurate resistance/AC-voltage as well.

That’s great if it’s a small box, 5440B is a mountain More separate devices you’ve got, more uncertainty you have to add, as well (AC/DC/ACI/DCI, not for resistance or capacitance obviously), I wish all instruments took a reference in input.

[TiN]

To be fair, prices I've listed above as "unknown boxes, sometimes with missing boards" and not "calibrated good" devices. If you are a business and need a reliable tool that works and supported, then only option is 60k 5730A at the moment. 5720A was officially EOL'ed and out of support last year June. Also one thing if you want buy right now because you need it next week, and different story if you just want to get it some day and are in right spot, right time and with cash in hand... YMMV.

One can also cook some common current ranges from 5440+5200+5450 tandem, that would be adequate for most of workloads as well. Or cook few circuits for TIA use. 

For VFD its a board replacement (usually 600-1000$ part). Same goes to any other calibrator as well. I'd trade bad VFD compared to modern LCD crap with FPGAs and alike, which brick the unit altogether if broken. With shattered VFD you could always just use MFC over GPIB (given you still have controller board talking back to main CPU).

but calibration of the 5730A costs 2k4 at Fluke in germany.

Depends on calibration level and lab capability, there is no universal fixed price for calibrations. You can calibrate 3458A for $300 too. Or $3000, depends on performance. Or $10k if you want JVS direct data... Same goes to calibrators . Hence I calibrate in-house and we do our secret cal club inter comparisons.

[Arhigos]

For VFD its a board replacement (usually 600-1000$ part). Same goes to any other calibrator as well. I'd trade bad VFD compared to modern LCD crap with FPGAs and alike, which brick the unit altogether if broken. With shattered VFD you could always just use MFC over GPIB (given you still have controller board talking back to main CPU).

But most people using calibrators with met/cal, or other automated systems. I don't think that vfd is even a big problem

[volvo_nut_v70]

Unfortunately METCal is only semi automated, depending on the instrument and procedure. There are some procedures where the operator relies on the calibrator display for certain operations.

[gnuarm]

I don't know  about a 5720, but I can change a 5700 into a 5798 by moving two toothpicks. 

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[TiN]

Rearranging gear yesterday, took a photo of current state of "Hulk-3" project.

Minor repairs may be required.   
Just need to get 2 more missing boards and we will have complete broken unit.