Fluke 5200A AC Calibrator Repair Videos - In Progress - Page 1
Forum section: electronics / repair

author: TheDefpom
author_rank: Frequent Contributor
timestamp: September 26, 2017, 07:45:34 am
content: I am in the process of repairing this old Fluke 5200A AC Calibrator, this is the first video in the series, I already have footage ready for part 2, and part 3, which I will be publishing soon also.https://youtu.be/zrTCKwn1G6A

author: texaspyro
author_rank: Super Contributor
timestamp: September 26, 2017, 11:45:37 am
content: The 5200A uses a RC oscillator (I think it was 10 MHz) to generate the clock. Mine was rather wonky. I replaced it with a DIP-14 TTL crystal oscillator.

author: 3db
author_rank: Frequent Contributor
timestamp: September 26, 2017, 11:58:03 am
content: @texaspyroWas the original a sine wave ?

author: texaspyro
author_rank: Super Contributor
timestamp: September 26, 2017, 12:26:22 pm
content: What ever it was, it fed TTL. It was around 15 years ago...At one time I did a PCB to make an extender cable for the 5200A boards. I used a pair of 50 pin ribbon cables. The same PCB is used on each end. For the edge connector, I used one with wire wrap pins and bent the pins and soldered them to the edge tab on one of the PCBs. I have never used it (never had a need). I am a bit wary of it since some of the backplane slots have like +/- 300V on them... a bit high for ribbon cable. I did check it with a 1000V insulation tester and it passed.

author: Dr. Frank
author_rank: Super Contributor
timestamp: September 26, 2017, 04:30:16 pm
content: Quote from: texaspyro on September 26, 2017, 11:45:37 amThere's one tuned LC - oscillator, to generate digital 10MHz for the PWM of the DAC, which generates a variable precision DC reference voltage of about 0.3 .. 3V, out of an SZA263. That's really great old school stuff.The programmable / variable output frequency of 10 Hz .. 1MHz is generated by a quadrature RC oscillator, which has nothing to do with these 10MHz...The output amplitude of this analogue oscillator is compared to that DCV reference and regulated to exactly the same RMS value by a fast precision rectifier. Also great stuff.Although this design is pretty old, it's really precise and stable, if repaired properly.Good luck, DefPom, that it's been the PSU subassembly P23 only.That fat TO-3 component is a 5V regulator, 3A or 5A, not a transistor, and hopefully ok. (*)The other transistors might still be available, or have compatible new parts.Frank(*) It's obviously an LM123K, a 5V, 3A regulator, still available, or replaceable.

author: Tony_G
author_rank: Super Contributor
timestamp: September 26, 2017, 04:52:18 pm
content: I bought this as the extender for working on my 5200A - Mine is currently stable but the quadrature output isn't accurate so I need to get back in and work on that at some point.eBay auction: #222653463018TonyG

author: TheDefpom
author_rank: Frequent Contributor
timestamp: September 26, 2017, 06:30:36 pm
content: Thanks for the feedback, I do have the power supply repaired, I show that in part 2 and part 3 (which I haven't published yet), it still has issues, one of the +-15v power supplies which is linked to a reference supply is outputting the wrong voltage, I need to dig into that more, there is no output, and is showing overload continuously, again I haven't dug into those yet, but suspect a -190v regulator fault.

author: Tony_G
author_rank: Super Contributor
timestamp: September 27, 2017, 11:54:00 am
content: My overload problem was actually with the oscillator (I can't remember if it was the oscillator or the control board). I happened to have a good board so I just swapped it out and that fixed it.I never looked into what the board fault was unfortunately.TonyG

author: TheDefpom
author_rank: Frequent Contributor
timestamp: October 01, 2017, 05:21:41 pm
content: Part 2 video:https://youtu.be/HFIFm-kLS6U

author: TheDefpom
author_rank: Frequent Contributor
timestamp: October 09, 2017, 08:15:08 pm
content: Part 3... its going to be a loooong series.https://youtu.be/j3x4d4zIY94

author: tautech
author_rank: Super Contributor
timestamp: October 09, 2017, 08:36:36 pm
content: Oh hell, I've only watched Pt1 so I've got some catching up to do.I enjoy such drawn out detective stories Scott, so keep it up and I hope it all ends well.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: October 09, 2017, 08:56:18 pm
content: I had to dig out my 8842A 5.5 digit meter to do some precision measurements on resistors... but I could use a 6.5 digit in my equipment list (cough, siglent, cough free, cough)

author: TheDefpom
author_rank: Frequent Contributor
timestamp: October 13, 2017, 07:45:47 am
content: Part 4... it's going to be a long series.https://youtu.be/k1cfaH26Sz0

author: fcb
author_rank: Super Contributor
timestamp: October 13, 2017, 08:27:05 am
content: I've got a pair of 5200A's (one is black plastic handles and one is metal handles).One is pretty spot on, the other isn't. So I look forward to watching the your videos when I have a few spare hours!I've also got a 5215A, but I dare not power that up until I've had the lid off it and bought an HT probe (it has +/-2500V rails inside).

author: Bill158
author_rank: Regular Contributor
timestamp: October 14, 2017, 08:17:01 pm
content: Quote from: TheDefpom on October 13, 2017, 07:45:47 amYou really have a "tiger" by the tail on this one. Part 4 of your video seemed a little "disjointed". You were working on the basic power supplies and then suddenly you were working on the A12 Reference Board. Then it goes back to the basic power supplies and then you are disassembling the A12 Reference Board and working on that one again. But I was able to follow once I saw Part 4 to the end. I am glad you got a clear and correct manual for the 5200A. I have one and it does differ somewhat in the areas you are working on, i.e. the A12 Reference Board. As you have discovered R-45 on A12 is a 85.75 WW Card resistor which probably has a T/C of something like 10 ppm/C (or better). Since this sets up the basic output voltage of the Reference Amp U30 eventually you should find something that has a very good T/C. The value probably isn't all that important as long as it is around 86 ohms because you have R-48 which will give you some latitude in setting the final voltage of the Reference. I hope that none of the other "matched" resistors for the Reference Amp are damaged.I was confused at the end of Pt. 4 as to where you had the FLUKE meter hooked up when you were getting around 6.985 volts. Are you on the input of U29 or U33? But then you seem to be looking at the basic power supplies again and not getting what you expect. You realize that the A12 Reference Card supply is to set the precision AC output of the 5200A and I don't think has any effect on the basic power supplies. However I could be wrong here and will have to look at the whole circuit.One other point that was in Part 1. You seemed to be confused as to the exact function of CR-11,12 and 14 in the A5A2 Power Supply Assembly. Those are "current regulator diodes". See the 1N5283 through 1N5314 JEDEC parts. The are N-Channel JFETS with the Gate hooked to the Source. This is the basic IDSS testing configuration for a 3 terminal JFET. The purpose of these CR diodes is to get the pass transistors Q12, Q9 and Q8 started up until the output voltage reaches the desired value set by R22/R23 for the -30V, R18/R19 for the +30V and R14/R15 for the -15V supplies.Just trying to help you here, good luck!Bill

author: TheDefpom
author_rank: Frequent Contributor
timestamp: October 14, 2017, 08:34:31 pm
content: Thanks for the feedback.Yes I was going back and forth a bit there, I thought I had the power supply sorted, but then realized it still wasn't right, as the +-15 and +20v rails weren't correct even when plugged into the main unit for the reference voltage for the opamp.The reference supply uses the+-15 and +20 v supplies, and then generates the 6.9v reference, which is fed back to the power supply board as an opamp reference, and this regulates the opamp to generate the +-15 and +20v rails, however that wasn't working because of the faulty resistors and I the blown opamp.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: November 03, 2017, 10:17:48 pm
content: Part 5 (sorry I published this about a week ago but forgot to put it here)https://youtu.be/IpUW8cbI2FI

author: texaspyro
author_rank: Super Contributor
timestamp: November 03, 2017, 11:01:50 pm
content: Spend the $7-$20 to get one of those "component testers" that are all over the place on Ebay. It will do a hell of a lot better job identifying and checking transistors and caps than a DMM. You just connect the part (up to three leads), press the button, and voila... you get a picture of the part with the terminals labeled and its parameters. Some darlington devices / power transistors with internal resistors can fool it.My preferred model is the "AY-AT" version with a socketed processor chip, color LCD display, and rotary encoder.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: November 03, 2017, 11:07:32 pm
content: I have various testers, all I am checking for is opens/shorts on the components, and the fastest way is with the dmm, if I need more information or a proper check I use my Peak transistor tester, you will see it used in some of the videos.

author: texaspyro
author_rank: Super Contributor
timestamp: November 03, 2017, 11:17:56 pm
content: I've seen LOTS of transistors that check out fine as two diodes, but utterly fail as transistors. You can then spend hours debugging the circuit because you thought a bad transistor was good because the DMM diode check passed. It pays to actually check the parameters of all your devices... particularly if they are in sockets. Oh, and never trust an in-cicruit measurement.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: November 09, 2017, 03:20:50 am
content: Part 6https://youtu.be/zJpIM-dOVrk

author: TheDefpom
author_rank: Frequent Contributor
timestamp: November 20, 2017, 10:01:46 pm
content: Part 7, I recorded this a month ago, I haven't had the chance to get back into it yet, as I have been too busy with more important projects.

author: apelly
author_rank: Unknown
timestamp: November 22, 2017, 09:03:54 am
content: I picked up one of these with a kaput power supply a while ago. Haven't had time to look into it yet, and these things do seem to be bears to fix, but if you're in AKL you're welcome to borrow it and try swapping some boards/comparing values.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: November 22, 2017, 10:26:33 am
content: Quote from: apelly on November 22, 2017, 09:03:54 amThanks for the offer, I will see how I go once I get sufficient time to start going through the boards in a logical manner, I will get in touch if I get stuck and need to do comparisons.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: December 13, 2017, 03:47:40 am
content: I finally got some time to get back onto this project, here is part 8 of the series:

author: Tony_G
author_rank: Super Contributor
timestamp: December 13, 2017, 04:16:11 am
content: Hey Scott,I'm on vacation for the next few weeks (so I don't need it right now) and I haven't been using my 5200A for a while anyway (I've used my 5440B because I'm calibrating some power meters). I'm happy to send you my A10 and other boards to help you find the guilty bastard - let me know.TonyG

author: TheDefpom
author_rank: Frequent Contributor
timestamp: February 23, 2018, 10:10:34 pm
content: Hi All,I just released that I forgot to post a few videos here!I have some more on the way soon to, and (spoiler alert) I have got it working!Part 9:Part 10:Part 11:Testing of oscillator functionality, which may be helpful to someone (I did this for the guest appearance on Dave's channel, so you may have seen it):

author: TheDefpom
author_rank: Frequent Contributor
timestamp: February 25, 2018, 09:33:29 pm
content: And Part 12 is published now too:

author: TheDefpom
author_rank: Frequent Contributor
timestamp: March 04, 2018, 03:50:12 am
content: Here is part 13:

author: TheDefpom
author_rank: Frequent Contributor
timestamp: March 12, 2018, 08:16:10 pm
content: Part 14.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: March 15, 2018, 07:16:30 pm
content: Part 15:https://youtu.be/ZPgE5YUoQ4Y

author: technogeeky
author_rank: Frequent Contributor
timestamp: March 16, 2018, 10:57:21 pm
content: Quote from: TheDefpom on March 15, 2018, 07:16:30 pmNice! Anything project in which a man takes 15 videos to get working is an awesome accomplishment!It sounds like you almost didn't believe what you were seeing when you kept saying "Yeah, it's working!" Hah!

author: texaspyro
author_rank: Super Contributor
timestamp: March 16, 2018, 11:17:18 pm
content: Quote from: technogeeky on March 16, 2018, 10:57:21 pmYou should see my 15 part video on the travails changing a particular little light bulb (that shall not be named, lest it gets any ideas)... now THAT was an accomplishment extraordinaire! Even Defpom would be awed!

author: Bill158
author_rank: Regular Contributor
timestamp: April 14, 2018, 06:32:16 pm
content: I was watching Part #17 on your repairing the FLUKE 5200A AC Calibrator when you are doing step 4-71 d and onwards. You are first assuming that your Siglent SDM 3065 (I think that is the model you are using as it is hard to read the exact model number from the video) Digital Multimeter frequency response goes to above 1 MHz. I am looking at the specs and it is only rated to 300 KHz at something like +/- 4%. But who knows what value it will give you at 1.05 MHz? You apparently didn't read Section 4-71 step "e" correctly in that it wants you to use a FLUKE 931BACdifferential voltmeterwhich has a frequency response to 1 MHz at 3%. Or at least some AC meter that can measure 1 MHz, as I don't think the Siglent can do the job at this step. Also I don't understand why you are getting a " - " symbol on the DMM when you are supposed to be measuring AC voltages? Did you change to the AC measurement on the Siglent? Also you seem to have the PLC on the Siglent to be set to 1PLC where you may need a larger value like maybe 10 PLC to stabilize your low level readings, either AC or DC. The 5200A should be able to give you a good stable output to below 0.1 mv ( less than 10 ppm ) at 10 vAC and 1 KHz with the DMM at 10 PLC. Mine does as measured on my 3458A at those conditions. I do see a +/- 5ppm ( 0.05 mv ) "flicker" on the 3458A. I am also using "SETACV SYNC" on the 3458A.Bill

author: TheDefpom
author_rank: Frequent Contributor
timestamp: April 14, 2018, 07:10:42 pm
content: Quote from: Bill158 on April 14, 2018, 06:32:16 pmThanks for your observations, I had read about using the differential volt meter, but as I don’t have one I have to use the best substitute I have.I am only using 1 plc to speed up the reading rate, when I need more precise readings I increase it, at the stage of the video I am really just trying to get it roughly working to try and narrow down where the output noise is coming from, the noise would be messing up the accuracy anyway.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: April 14, 2018, 07:30:09 pm
content: Part 16:https://youtu.be/YZ6FqGMT9xUPart 17:https://youtu.be/k_081FgY8l8

author: TheDefpom
author_rank: Frequent Contributor
timestamp: May 01, 2018, 08:43:45 pm
content: Part 18:https://youtu.be/_clhBn1YWMA

author: TheDefpom
author_rank: Frequent Contributor
timestamp: May 14, 2018, 02:43:54 am
content: Part 19...

author: fcb
author_rank: Super Contributor
timestamp: January 14, 2020, 11:01:16 am
content: Hi TheDefpom,Did you complete the 5200A repair and calibration - I saw you got to part#19..I have a pair of 5200A here (one black handled and one silver handled) - these are largely surplus (we have other calibrators), but I don't mind firing them up to pull waveforms measurements off them.