My first serious multimeter (Fluke true RMS) and I messed it up. Help - Page 1
Forum section: electronics / repair

author: highcap
author_rank: Contributor
timestamp: October 08, 2024, 05:52:21 pm
content: Hey friends, got this nice Fluke 8060A and I was eager to place a new battery and start using it.Since the 9V battery connector was corroded along with the battery, it broke when I pulled it out, so I was left with the raw red and black wires.Hold a 9V battery onto the wires just to see if it powers on, and it kind of did but very shortly and digits seemed to not be complete, then it faded out.Since I didn't had a good grip on the the small wires onto the battery tips, I have mistakenly reversed the polarity and the battery started to heat.Now the multimeter does not power up at all and kind of puts short on the battery (measured about 2,3 Ohm on the batt wires).Did I messed it up completely or there's some hope in repairing it? I have attached some pictures.Thank you everyone for any inputs!

author: stevopedia
author_rank: Contributor
timestamp: October 08, 2024, 06:45:39 pm
content: There's a good chance this is an easy repair! Do you have access to a soldering iron and another multimeter?If you look on page 139 the manual PDF (https://assets.fluke.com/manuals/8060a___imeng0300.pdf) you'll see the schematic for the main board of the meter. The part we're interested in, the power switch and such, is tucked away in the bottom-left corner. VR3 is a 12 V Zener meant to protect the meter from reverse voltage such as accidentally reversing the battery. In this case VR3 probably failed short, which means it did its job perfectly!Turn on the 8060's power switch, and then with the other multimeter measure the resistance across the battery wires inbothdirections. If VR3 failed short, you should see a very low resistance in both directions. Page 135 of the PDF shows where VR3 is on the board: placed vertically and tucked under the display, right next to the battery eliminator jack. If you cut or unsolder the wire coming out of VR3 and the short on the battery input goes away, then you've found the cause. Remove the original VR3 from the board andreplace it with a new 12 V Zener diodeto restore the 8060's reverse polarity protection. The meter will work without VR3, but if you accidentally reverse the battery again and VR3 is missing youwillcause irreparable damage to the meter.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 08, 2024, 07:04:29 pm
content: yep vr3 could have shorted out to protect the main section

author: highcap
author_rank: Contributor
timestamp: October 08, 2024, 10:32:12 pm
content: Thank you that's great news!I will first replace that diode before doing anything else, considering how I messed up with the polarity.I will post an update as soon as I have it solved.Best.

author: lowimpedance
author_rank: Super Contributor
timestamp: October 09, 2024, 02:09:04 am
content: And while your in there, check the miniature electrolytic caps for electrolyte leakage as this will damage the PCB.Its a common issue with these vintage meters, search the forum for details of 'others' repairs and possible suggested replacement parts.I would actually change them anyway as a preventative measure.

author: Dave Wise
author_rank: Regular Contributor
timestamp: October 09, 2024, 06:12:25 pm
content: When I got my 8060A a couple months ago it had probably sat unpowered for decades with daily and seasonal temperature swings but most likely in a dry location. I decided to try it without preemptive electrolytic capacitor replacement, since I saw no evidence of fluid egress.When I first powered it, it didn't work, displaying a few random LCD segments. After about a half hour it began to work normally. Later I removed the battery and probed the caps, with an ESR meter and an impedance bridge. They all read acceptable ESR, C, and D. I left them alone and it is still working.Make of it what you will.Dave Wise

author: Xena E
author_rank: Frequent Contributor
timestamp: October 09, 2024, 07:12:10 pm
content: Quote from: Dave Wise on October 09, 2024, 06:12:25 pmWise man indeedOld good quality caps will reform just fine in most circumstances, blanket replacement without good cause is just inviting trouble.

author: lowimpedance
author_rank: Super Contributor
timestamp: October 10, 2024, 12:28:34 am
content: Quote from: Xena E on October 09, 2024, 07:12:10 pmSure by all means check your caps and make your own decision depending on what's its worth to you. BTW I am the same, I don't replace caps blindly, but some equipment are notorious for their leaking caps and the resulting damage, that could have been avoided . For example, Keithley 2000 series DMM's would you risk it !Also I have an 8062a that lived all its life in an air conditioned lab and it had extensive damage from leaking electrolytic caps YMMV.Above all though great to see another vintage meter back in action

author: Xena E
author_rank: Frequent Contributor
timestamp: October 10, 2024, 11:34:08 pm
content: Quote from: lowimpedance on October 10, 2024, 12:28:34 amYeah, that's absolutely right, there are some brands of capacitors that are just awful, replace on sight junk. Ever come up against the red/black molded case Plessey electrolytic capacitors from the 1960s? Haven't found a good one yet, it's a case of knowing what's normally OK, (perhaps most brands), and what is garbage.It's just that there are those people that just dive in and shotgun the job thinking that just replacing a bunch of capacitors will fix any fault. The next type of personality just do it to good working equipment, because they think that's what you do for a restoration.... I've replaced all the caps in my xxxx and now it won't work, is a common comment on the help forums.

author: Dave Wise
author_rank: Regular Contributor
timestamp: October 11, 2024, 04:39:05 pm
content: All of my 8060A caps are Chemi-Con, unmarked but probably SR/SRC/SRJ series except for the RMS coupler which is LL series. All 85C temp rating and probably 1000h service life - the latter of which has been exceeded by orders of magnitude, but sometimes you get lucky - I run Tektronix oscilloscopes from the 1950's with mostly original electrolytics. OTOH I do check them now and then...

author: Zoli
author_rank: Frequent Contributor
timestamp: October 12, 2024, 06:45:05 am
content: Both the RMS converter and input protection diode bridge has '82 date code. AFAIK, the capacitors in the early series have a leaky habit, so is recommended to change them anyway.

author: highcap
author_rank: Contributor
timestamp: December 20, 2024, 02:38:45 pm
content: Update about the repair, diode was blown up, placed a replacement Zener and all went good!Here are the pics, thank you everyone again for chiming in to help!

author: Xena E
author_rank: Frequent Contributor
timestamp: December 20, 2024, 06:32:20 pm
content: Well done.Thanks for the update.X

author: GLouie
author_rank: Regular Contributor
timestamp: December 20, 2024, 06:48:18 pm
content: I am in the camp recommending replacing the electrolytic caps regardless.My personal 8060A, bought new, went bad after 35 years, and had several leaking caps that were not very visible until removed.There are several repair threads here such as in the "old fluke multimeters" thread.Thes units are just too good to risk damage IMO.

author: blue_lateral
author_rank: Contributor
timestamp: December 20, 2024, 09:22:04 pm
content: On these particular units, IMO you are begging for trouble by not changing the caps.