Replacing relays in a 5440B or 5440B/AF - Page 1
Forum section: electronics / general

author: Tony_G
author_rank: Super Contributor
timestamp: October 25, 2016, 04:29:18 am
content: Hi All,I've been speaking to Fluke about my 5440B/AF which I have there for calibration and they're telling me that they can't calibrate it on the 1000V range without changing all the relays. So I thought I'd ask the forum members who happen to have a 5440B or the B/AF variant if you've ever replaced the relays - For whatever reason they're telling me they need to be replaced and not simply cleaned.They've given me the following quote for parts:QtyPart NumberCost13AZ431-17-205897.004AZ421-14-201300.361AZ420-12-20356.345AZ431-16-200345.00Parts Total $1598.70(USD)This is a tad excessive for hobbyist use really (especially when you need to add the labor and calibration on top of that). These are allAmerican Zettlerrelays but Fluke actually told me that I should be able to get cheaper parts than the AZ ones. I assume that if I get the cheaper relays then they'll replace them for the labor cost.There are several manufacturers that have compatible series:BrandSeriesMagnecraftClass 67Nais PanasonicK 6-PoleSchrackZK/ZLTelemecaniqueT154TycoR10Has anyone used any of these instead of the American Zettler ones? Any recommendations on brand/where to buy? At this stage I'm wondering if it isn't simply better to get the thing back from Fluke to see what impact cleaning the relays has - Then living with 'self-calibration'.Any thoughts?Thanks,TonyG

author: Bill158
author_rank: Regular Contributor
timestamp: October 25, 2016, 06:55:01 pm
content: Quote from: Tony_G on October 25, 2016, 04:29:18 amI have a 5440B and 5440B/AF, both of which I have cleaned these relays, what ever brand FLUKE used in these units at the time of manufacture. It is fairly simple to remove the plastic covers and then applying a cleaner to the contacts, exercising the armature manually, and then putting the cover back on and reinstalling the relay. I also spray the contacts that go into the sockets. I used DEOXIT G5 as the cleaner as it is specifically designed for gold plated contacts, which is what the contacts appear to be. Of course FLUKE used gold plating for reliability. I see that American Zettler offers this option when ordering. American Zettler is probably the preferred vendor for this relays at the present time, no matter what vendor FLUKE used in the past.It does take a bit of patience to remove the plastic cover as they are held on by a "one way" retainer on each of the "long" side of the rectangle. You must insert something under the cover on each side to get the latches to release and then just slide the cover off.I did all of this as a preventative measure before calibrating them and using them. I have never sent these into FLUKE for cal as I have the necessary standards to calibrate them (732A, 752A etc.) so I don't know what FLUKE would tell me if I had sent them in.My guess is that FLUKE wants to put new relays into the 5440 because they simply don't know the condition of the relays that are there now or how many cycles they have been used or what kind of lab conditions they have been subjected to during their lifetime. This way FLUKE can guarantee that the calibration will be stable for the period that is required in the specs. It is more an issue of meeting the specs than if the relays are worn or not. It is easier to simply replace these than to worry about a faulty relay and having to do a warranty repair at no charge later on.IMHO of course,Bill

author: dacman
author_rank: Frequent Contributor
timestamp: October 26, 2016, 12:11:23 am
content: I use the R10 or AZ, whichever I can find. (I prefer the AZ.) Onlinecomponents.com usually has the lowest prices that I've found, but I've noticed that the prices you've listed are lower. I've burnished more of these relays than I've replaced (gold plated silver contacts, bifurcated, which are dry circuit rated). The relays can be pulled and tested, and I don't burnish them unless they need it. (I'd measure the contact resistance and close the relays with a bench supply.) The R10 and AZ relays in the 5440B are not soldered in (they are held in with a clip).

author: Bill158
author_rank: Regular Contributor
timestamp: October 26, 2016, 03:05:17 pm
content: One other thought on this subject.Ask FLUKE why they feel they have to replace ALL of these relays? My thinking is that there could be 2 possible reasons.1. As I stated before it could be a preventative measure to insure the cal will be good for a year.2. FLUKE has experience with the brand of relays used in your 5440B which indicates that these relays are prone to failures.I can't remember what brand of relays were in my units. I guess I will have to look someday. You could ask them if you sign a waver about not replacing the relays, stating that you will accept the calibration with NO guarantee of future performance, they just might do the cal anyhow.IMHOBill

author: lowimpedance
author_rank: Super Contributor
timestamp: October 26, 2016, 10:43:00 pm
content: Just for relay brand reference, I have a 5440A and a 5440B currently in bits and both units are using American Zettler relays, don't know if they're originals or not though!.

author: Mav_2014
author_rank: Contributor
timestamp: March 29, 2018, 09:34:09 am
content: Sorry for resurcting this from the dead but did anyone have any joys or can anyone recommend a replacement for these AZ420 as I've a 5101B and one of these is totally shot.Thanks all.

author: wn1fju
author_rank: Frequent Contributor
timestamp: March 29, 2018, 04:54:59 pm
content: Look at my posting from 9/30/17 on the Metrology forum: Fluke 5440B "Repair" Search the forum for that title.I replaced ALL of my 5440B relays with a set of 62 new inexpensive DPDT relays! Call me an idiot, but after six months I can truthfully say that the unitworks perfectly. Also is much quieter (the new relays hardly make any noise) and draws less power.

author: Mav_2014
author_rank: Contributor
timestamp: April 02, 2018, 01:41:33 pm
content: Wow! I don't think I've the time or patience to go that far with it lol but nice job!!I'm just trying to find a direct replacement to plug in for the zettler but finding something is proving a but of a task. 2 I've bought from eBay us, 1 I've paid for and no response.... great, the other has responded to say he'll post to the uk but still waiting to hear back after buying it....Needed pretty desperately as the 5101b in the lounge is soon to start causing problems.... and it doesn't belong there!! On the plus side if I can get hold of one or anyone knows a direct replacement I can then at least shed some light on this overlimit fault