Fluke 5700A problem - Page 1
Forum section: electronics / repair

author: JR.junior
author_rank: Newbie
timestamp: March 17, 2025, 06:56:48 pm
content: Hello all.I have a weird problem with a Fluke 5700A. When powering up teh calibrator it hangs on at "Starting Remote Interface. Please Wait..." and the output display stays dim and won't boot further. But if I apply 190 VAC (with variac) into the mains inlet, the calibrator boot completely. And then I turn the variac to 230VAC as it should be and can use the calibrator normaly. Have anybody a Idea where could be the problem? At 230VAC, I have to start it several times to get it running..

author: picburner
author_rank: Frequent Contributor
timestamp: March 17, 2025, 08:56:58 pm
content: Yes, it is really strange. It could have something to do with the power supply of the instrument.How old is the instrument? Have you done any maintenance? Have you checked the various electrolytic capacitors?Once you have managed to get it to start, try to run the self-diagnostics (Setup Menus and then Self Test & Diags) and see if there are any errors.

author: Jetecnet
author_rank: Contributor
timestamp: March 18, 2025, 12:55:33 pm
content: I've had this several times with the 5700A, try exercising the voltage selector switches at the rear several times, with power off obviously. I'm in the States (120V)and I found it was only using one primary. I guess you are 230V so I don't see why it would apply but worth a try. JC

author: JR.junior
author_rank: Newbie
timestamp: March 18, 2025, 05:50:23 pm
content: Yes, I forget to mention that I have switched the voltage selector to various voltages (220,230,240) and run the self diagnostics, two fails 2923, and 2825. Repairred the issues, self diagnostics pass now. Changed all the electrolitics on all pcbs and voltage stabilators, includig digital assembly. Checked all the pins for cold solder joint, complettely dissasambled the calibrator, checked all the varistors. Still problem at start at 230VAC..

author: picburner
author_rank: Frequent Contributor
timestamp: March 19, 2025, 04:43:54 am
content: Try to monitor what happens to the Reset outputs of both A20U1 and A17U60 while you vary the voltage from 190 to 230V.Or what state these outputs are in by immediately applying 230V.(Please note that these two measurements imply references to different grounds (0V))Just to know: did you buy a faulty 5700A and you trying to repair it or did the instrument work perfectly before and then it broke?

author: JR.junior
author_rank: Newbie
timestamp: March 22, 2025, 08:54:13 am
content: Reset ICs are both ok. The problem lays on the Digita assembly. The TP9 doesn't pulse at startup. Could be a DUART problem..

author: picburner
author_rank: Frequent Contributor
timestamp: March 22, 2025, 10:52:13 am
content: The duart A20U31 is responsible for many things. It remains to be seen whether is it the culprit or one of the jobs it is supposed to control.Could it be that a fan is faulty or dirty and is starting slowly and drawing too much current?

author: JR.junior
author_rank: Newbie
timestamp: March 22, 2025, 04:11:49 pm
content: Fans are not the problem, already powered up without them. Same story. I read the EEPROMS..U18 is empty no data readable, U15 has some problems. Ordered yesterday new EEPROMS and some other ics (OPTO Fiber driver included..). BTW Calibrator was working ok, about 1,5 month ago started to showing this problem.Thx for the help.

author: picburner
author_rank: Frequent Contributor
timestamp: March 22, 2025, 05:20:20 pm
content: Attached are all the eprom dumps for a first series F5700A including the GAL jed files.

author: JR.junior
author_rank: Newbie
timestamp: March 23, 2025, 08:50:49 am
content: Perfect! Thanky you! I have only dumps for U15-U18.