FLUKE 8810A Display Blinking - Page 1
Forum section: electronics / testgear

author: Bpeter
author_rank: Newbie
timestamp: May 06, 2017, 01:34:49 pm
content: On this forum I've read several discussions which were including this malfunctioning as well !But , due to other highlighted faults, no explanation has been given to this specific faulty behaviour ...In my case : at switch-on , for less than 1 second , the display try to show the right value, and, suddenly,everyone of the display's segments start blinking +/-18888888 flashing ....regardless to: MODE (Vac-Vdc- Ohm) - Range - etc.I tryied even to remove the optional units : Vac Module & OHM Module ... same blinking !I checked-out all power supplies as indicated on the manual : they are PERFECT !Anyone could give explanation , and/or on how to fix the problem will be welcome.THANKS in ADVANCE to the FORUM !Peter

author: tautech
author_rank: Super Contributor
timestamp: May 06, 2017, 08:32:34 pm
content: Welcome to the forum.There might be some clues found in this thread or by following the links in some posts there:https://www.eevblog.com/forum/testgear/old-fluke-multimeters/

author: coromonadalix
author_rank: Super Contributor
timestamp: May 07, 2017, 01:52:17 am
content: https://archive.org/stream/FLUKE_8810A/FLUKE_8810A_djvu.txthttps://forum.allaboutcircuits.com/threads/repairing-a-fluke-8810a-multimeter.77478/Is it because it's overflowing

author: Bpeter
author_rank: Newbie
timestamp: May 12, 2017, 06:28:46 am
content: Thanks for indication given in "Old Fluke Multimeters" section but I didn't found anything related to my problem ...As far as I've seen "drtaylor" should know a lot about this kind of trouble ... But probably he didn'nt read yet my thread.Thanks anyway ... but the problem is still there ... BLINKING all the time !

author: macboy
author_rank: Super Contributor
timestamp: May 12, 2017, 02:21:56 pm
content: Have you even looked at theinstruction manual?If you had, you would know that,QuoteNow that you know that, you know that there is some issue that is causing the thing to think the input is overrange at all times, after completing the first reading. The service manual is floating around in pdf format, easy to find. have a look and see what you can figure out. In particular, study sections 4-52 to 4-60 "A/D Converter or Control and Display". There is very detailed troubleshooting info there.

author: peterkos2
author_rank: Contributor
timestamp: March 31, 2024, 08:36:25 pm
content: Greetings.I got my hands on this older Fluke 8810A multimeter.Of course, I immediately turned it on and the display just flashed and it was dark. But when I opened it, I couldn't believe my eyes - the switch was in the 115V position. Of course, farted insurance.A normally prepared spare inside, I replaced it, the multimeter started up, the numbers are just running around, but even when measuring it fluctuates quite a bit, it depends on the ranges - the bigger the more it fluctuates.I found the service manual and checked the voltages on the test points, on some it holds perfectly +18V - OK-18V- so there is -24V-13V - there is -19V+7V - OK-7V -OK+35V and -35V are standardThe problem is probably in the circuit of the CR30 bridge. The power supply of the U18-NE5534N is -26 and +16, I don't really understand it - like +16V, I understand there is a 10V zener, but -26V goes directly from the bridge...I tried everything I could, but I can't figure out what the problem isI will be glad if you direct me if possible.Thank you all for the answers 😀

author: J-R
author_rank: Super Contributor
timestamp: April 01, 2024, 02:08:35 am
content: I am not familiar with this specific model, but as a general comment did you check the capacitors and clean the front panel switches?

author: peterkos2
author_rank: Contributor
timestamp: April 01, 2024, 11:05:35 am
content: I checked the capacitors and they are fine, just the capacitor on the 9V branch is instead of 4700uF a little over 6000uF and the ESR is excellent, I don't understand that. I sprayed all the buttons

author: yo0
author_rank: Regular Contributor
timestamp: April 03, 2024, 04:09:26 am
content: For the op, check the 1 mhz crystal oscillator, seen similar behaviors in the past twice,best regardsPio

author: floobydust
author_rank: Super Contributor
timestamp: April 03, 2024, 05:39:13 am
content: Quote from: peterkos2 on March 31, 2024, 08:36:25 pmI would guess U18 is damaged from the overvoltage, you have NE5534 rated 44V and old service manual gives rated max 36V for '301.Fix the -18V rail before you damage parts. Not sure about 10V zener CR34 1N961A or Q63 PNP 2N4890 TO-39 if they are OK.U17 - Fluke 313106 Motorola MC723CG for the +18V rail, it also requires the +7V REF.U18 - Fluke 363515 AD301A, LM301AN but OP has NE5534 for higher voltage.U19 - Fluke 355107 Motorola MC7805CTThe +18V is the reference for the -18V rail, so they are dependent.The -13V rail is 5V above the -18V rail.If you ran it at 2x mains input, uh the filter caps might be damaged as well.edit: redid post, it was out.