Fluke 5200A alignment Problem - Page 1
Forum section: electronics / repair

author: ken goodhew
author_rank: Newbie
timestamp: March 13, 2025, 07:34:40 pm
content: Hi Gang,i am trying to do the oscillator alignment on my 5200A which went ok until step 23 on page 4-56 when it states that you should get "total spread of approximately 13 mv" ie:- +7to -7 mv whereas i get +14 to -13mv for a total spread of 27 mv.My question is is the 13 mv total correct or should i get +- 13mv as in my case.Given that i have found several other mistakes in the service manual writings i was wondering if this may be also a mistake.If the total 13mv spread is correct it leads me down another rabbit hole.Any advice welcome.Ken Goodhew.

author: benj38
author_rank: Frequent Contributor
timestamp: March 15, 2025, 08:48:34 pm
content: For what it is worth, the way I read the manual it means that it should go from some positive value +xV to some negative value -yV, where x+y ~= 13. Looking at other steps in the process, I believe that if they meant that it has to be symmetric about 0V (i.e., from ~ -6.5mV to ~ +6.5mV,) they would have said so.In short, I can not comment on whether there is a mistake in the manual, but the way I read it your span is too large.

author: bdunham7
author_rank: Super Contributor
timestamp: March 15, 2025, 09:33:10 pm
content: First, what problem are you trying to solve? I don't recall the answer to your question and I don't have a 5200A here to test, but if you start at Step 20 and proceed all the way through Step 42, what are the results? Assume that you answer the questions regarding the 13mV spread--which appear multiple times--as a "yes" and note what the exact results were. My guess is that +/- 13mV or so is fine.

author: ken goodhew
author_rank: Newbie
timestamp: March 19, 2025, 09:18:57 pm
content: First a bit of history on my 5200a problem.My 5200a has been working fine for some time until one day i turned it on and whilst every thing appeared normal there was no output.After waiting some time to get an extender card to work on the instument, I proceeded to carry out the troubleshooting procedure in the manual up to checking voltages on the oscillator board and this is where i ran into the + - 13 mv or + _ 6.5 mv conundrum as the way it was written i was not sure which was the correct interpritation given that just previously i has found a number of specified test point numbers were incorrect and were actually one number out.So i was wondering about my interpretation of the text as in a previous step it asked to verify + _ 25mv. (which was correct)So when i got to the step asking to verify "a total spread of 13mv" and i got + _ 25 mv again i was a bit suspicous of my interpretation.However i think the text is correct ie:- + - 6.5 mv, as test pionts further down that asked for a total spread of 13 mv also had wildley incorrect values.This leads to the rabbit hole at step 69.After a bit of poking around and testing i decided to go back and look at the power supply card again to be sure that the voltages were still correct, which they were, but this time i checked the 15v power rail for ripple with the cro , a step iskipped as i had previously replaced all the electro's on the board.This is when i discovered what may be a problem or just a distraction in that whilst the ripple is within acceptable limits there are what appears to be quite large switching spikes on the 15v rail.At this stage i have not done any further investigation of this problem due to a lack of time.Any comments aboit this would be welcome.As a side note i have substituted a spare osc board from a parts unit that i had and still get the same results so unless i have two osc boards with the same fault I then started to look elsewhere, eg. the power supply.

author: Dr. Frank
author_rank: Super Contributor
timestamp: March 20, 2025, 08:10:45 am
content: Hi volt-nuts fellow, Hello Ken,I just discovered your question, as this site was not used for a long time.. I’ll look for your request on eevblog as well.First off, I never got to this long check table for the regular calibration and adjustment procedure, as this is obviously intended as a ‘troubleshooting sequence’ only, see hint 4.93 on page 4-20. The adjustment process is much shorter. If your 5200A works properly, I suggest to not fiddle around with that long procedure.. as you would probably fall into that rabbit hole.I understand this paragraph, that you should see a variation of about 13mV in total, going through zero, i.e. that could be asymmetric around zero. 27mV therefore would be too high, but as you said, the manual is full of errors, and probably there could have been a modification (Engineering Change) at one time, so that the spread was enlarged by re-design.As far as you can align that feature to zero, I guess, it’s ok.Frank

author: Bill158
author_rank: Regular Contributor
timestamp: March 20, 2025, 04:46:53 pm
content: Ken:I have a F5200A but have not had to troubleshoot it very much. The only problem I had was that the output voltage drifted a LOT. Turned out to be a leaky FET. As the temperature went up the leakage got a lot worse. I believe that FET was either Q9 or Q11 on the A12 Reference Supply PCB. My point here is that if there is no output from this board then the 5200A output voltage will be 0 volts. A quick check would be to check the voltage at P51 on A12 and see if this DC voltage varies as you set the front panel output voltage dials. This is my first quick guess of what might be wrong. Of course check all power supply voltages as shown on page 15 of the attached FLUKE 5200A Student Handout book. The Troubleshooting section starting on page 15 could be helpful in you finding your problem. I think there is troubleshooting information in the book that is not in the 5200A manuals.I have also uploaded the Student Handout to K04BB.Good Luck,Bill

author: ken goodhew
author_rank: Newbie
timestamp: March 21, 2025, 02:55:22 am
content: have downloaded the 5200a student handbook so will have a read before going further.I do not have any output from the oscillator board.