Fluke 5440B repair

[leighcorrigall]

If you have another 5440B that you do not mind opening, I would suggest swapping those cards, including the transformer, to see if you can isolate the problem.

This may be my shortest path to success, as I do have my 5440A, and they're very very similar, if not outright identical (other than the display board). In fact, I seem to recall I identified a couple other less know differences going by just the SMs, which may be documented in my 5440A thread.

In any case, I need to collect some guts to begin such an endeavor, as maneuvering two behemoths like these guys are are not for the faint of heart (or people liking theirs backs working OK). I need to wrestle them in a way where I could have both open side by side, and this in my cramped workshop will be tough.

I have reviewed the manual and seen enough teardowns to agree with you that there are very few differences between the A and B versions. The rear interface panels are different, too.

Be careful. The plastic handles are prone to breaking and should not be used for moving the unit. I move the instrument by sitting it on an office chair and moving it around my office when I need to work on it. One of my long-term goals is to replace these handles with steel equivalents so that I don't have to worry about breaking something off. My 5440B will be with me for a long time because it is tremendously reliable and has excellent specifications.

[Rax]

One of my long-term goals is to replace these handles with steel equivalents so that I don't have to worry about breaking something off. My 5440B will be with me for a long time because it is tremendously reliable and has excellent specifications.

If you ever get to, I dunno, generate some cnc files (or other machining) you can share, or maybe have a few more made, I'd gladly get that if you're willing to share. Cover costs, etc, of course.

[leighcorrigall]

One of my long-term goals is to replace these handles with steel equivalents so that I don't have to worry about breaking something off. My 5440B will be with me for a long time because it is tremendously reliable and has excellent specifications.

If you ever get to, I dunno, generate some cnc files (or other machining) you can share, or maybe have a few more made, I'd gladly get that if you're willing to share. Cover costs, etc, of course.

If you are suggesting that I make a CAD model, I have already done so. Merry Christmas.

I have not formally shared them on EEVBlog because I still have to confirm the dimensions. It should be a near-identical copy.

Please let me know if I should pursue this. The material selection should also be correct. We will have to think about that.

EDIT:

According to the service manual, the handles are as follows:

Table 5-1 (5440B Final Assembly) and Table 5-2 (5440A Final Assembly)

Reference Designator, Description, Stock No., Supply Code, Part No., Quantity

MP 2, Corner Handle 8.75", 656199, 89536, 656199, 2
MP13, Corner Handle 8.75", 656199, 89536, 656199, 2

A private conversation with Rax confirms that these handles are interchangeable between the Fluke 5440A and the 5440B.

A single part (656199) can be used on all four corners because of the symmetry.

[Rax]

The other things I'd like to see as a 3D print file is the spacers used inside these 5440s (see pic). I'll dig up the part number and real name, but anyone having opened one of these has stumbled upon these little knoblets. They become very brittle with time, and I have not run into the situation where I'd pull them with "no victims" in a new unit having landed at my desk.

I'll give a shot to making some 3D files for this and see what comes out.

[Tony_G]

Random question Rax, did you replace/check the relays? One of my 5440s Fluke rejected for cal due to relays and I've never got around to addressing.

Just wondering,

TonyG

[Rax]

Random question Rax, did you replace/check the relays? One of my 5440s Fluke rejected for cal due to relays and I've never got around to addressing.

Just wondering,

TonyG

Tony,
Not really, no. I've just ran some of the corresponding diagnostics and I think my next step will be to swap modules to localize the issue (as I have this other 5440A that works correctly).
On checking the relays as its own thing, I am not entirely sure how I'd ago about that, need to think about it and figure it out. It's a good recommendation though.

[Tony_G]

I wouldn't have bothered getting the unit calibrated but I live down the road a bit from Fluke so I could drive the unit to their location rather than shipping it - I'm not sure how they determined that the relays were an issue (metrology, volt-nut noob...) but I haven't tried some of the suggestions of cleaning the relays.

Interested to see what you discover.

TonyG

[leighcorrigall]

The other things I'd like to see as a 3D print file is the spacers used inside these 5440s (see pic). I'll dig up the part number and real name, but anyone having opened one of these has stumbled upon these little knoblets. They become very brittle with time, and I have not run into the situation where I'd pull them with "no victims" in a new unit having landed at my desk.

I'll give a shot to making some 3D files for this and see what comes out.

If you keep the parts, they can be glued back together with epoxy and care. Once dry, you can use a razor blade to clean off the excess. I think I have a CAD file for them somewhere, as I was also concerned about them breaking. Unfortunately, I have no time to print them right now, but if you remind me after August 12th, I can see if I can fabricate them with a high-quality printer. You have my email.

I think I also saw a talk about calibrating this unit. I highly recommend that you do not calibrate a unit until you have had plenty of experience with it (> 6 months of operation and use). If there is a subtle fault, you may be wasting your money. Believe me, I made the mistake of being hasty a while ago with an Advantest R6581T.

[Rax]

The other things I'd like to see as a 3D print file is the spacers used inside these 5440s (see pic).

I think these are Fluke 421776 ("DORCAS?..."). So I made this in Fusion.

[Rax]

This afternoon I finally got the earthmover (...) to carve out some room at the bench, enough to have two of these behemoths open side by side. Not sure I'll be able to get the car we usually garage inside the garage tonight...

So, I was able to swap modules from the known good unit to the issue unit such that I'd isolate the issue. And this far tests are a bit confusing. Per SM (p.4-14), given the error message, A8, A9, and A4 are prime candidates for issues. A4 and A8 A9 seem to change nothing, essentially, so I'm deeming them good. Swapping A9 A8 doesn't fix the issue, but instead returns a different error. Actually, errorS! Initially, there was something about, I think, "inside guard" (it was one time and I didn't write it down immediately), and now I'm consistently getting "OUTPUT LIMIT FAULT. OUTPUT OVER VOLTAGE." But, this was upon me asking it to output 10V, and I didn't see it outputting more, so that's a bit weird. It seems there's some false flag errors triggering or something.

I'll dig down deeper, but if anyone sees any sense in the above, I'm all ears. All I can conclude this far is that the issue may have to do with A9, though a known good  module didn't fix it. For anyone asking, the module in both units is a "5440A" module, so I don't suspect any updates to the "B" unit modules make the swapped "A" unit unfit.

[Rax]

With the replacement A9 A8 board, if I try to output a "previously error condition triggering output" (say, 100V), I'm still getting the "UNDER VOLTAGE" error. If I try to output, say, 10V, I'm getting an "OVER VOLTAGE" error. Outputting 10V was successful with the original A9 board. So there seem to be new errors of sorts with the replacement board.

I think I'm just going to have to take a very close look at the trouble unit's A8.