Fluke 8050A -- Received it today - Page 1
Forum section: electronics / testgear

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 02, 2017, 08:26:36 pm
content: It was to be my first decent multimeter. I guess I get what I pay for. ($20 plus $10 shipping).Despite the guy saying it is in "great condition" (which the photos he took seemed to depict), there was a big lump in the front panel that I saw immediately, that you just don't see from the angle he took. Don't know what could of caused that.. but it was damaged some how.Also, I just now notice he took photos of every side but the back. Well the seal is off the back, so it must have been tampered with.It turns on... the display works fine. But wow it's hosed lol.6.00V reads around 6.5V.a 22 ohm resistors reads 30 ohm. But interestingly the ohms keeps dropping over time. Over about two minutes it dropped down to 25 ohm and pretty much stayed put or was just at a crawl so slow downwards to 22 ohm .. I dunno.With my VERY limited experience of electronics, I am guessing it is electrolytic capacitor related? It reminds me of measuring a cap as it is turned on or off.

author: technogeeky
author_rank: Frequent Contributor
timestamp: March 02, 2017, 08:45:57 pm
content: No pics? For shame!

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 02, 2017, 08:58:30 pm
content: Quote from: technogeeky on March 02, 2017, 08:45:57 pmThis is the photo he took of it:I didn't even notice that lump below the DB label and he didn't point it out in the description nor took special photo of it at alternate angle.. described it as great condition lol. If I was selling that I would of pointed that out to the buyer. Seems deceptive. Well it turns out to be quite a dimple protruding out .. I don't get it.. what could of caused it. Some force from within or someone tampering with it. EDIT: Again it looks like nothing in this photo, from this angle.

author: retiredcaps
author_rank: Super Contributor
timestamp: March 02, 2017, 09:22:01 pm
content: Quote from: JenniferG on March 02, 2017, 08:26:36 pmThe above may be fixable. First, post clear focused pictures of the pcb. Multiple shots will help. We are looking for something obvious like a blown or bad component.If the inside is dirty a simple IPA bath of the pcb might correct the above problem. Otherwse, we can check the input protection components like the PTC, MOVs, etc.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 02, 2017, 10:13:30 pm
content: Do I need to be concerned about battery back up or NV RAM calibration data? I don't want to lose the calibration data messing with the pcb. I have to take it apart a bit because the display board is in the way

author: james_s
author_rank: Super Contributor
timestamp: March 02, 2017, 10:17:32 pm
content: I'm not familiar with the 8050A, but I wouldn't expect there to be NVRAM in such an old meter, it's probably just some old fashioned trimpots. This should be an interesting project, see if you can find schematics and have a look inside. You'll probably need another meter to diagnose this one but it never hurts to have two meters anyway.

author: Andy Watson
author_rank: Super Contributor
timestamp: March 02, 2017, 10:43:26 pm
content: Quote from: JenniferG on March 02, 2017, 10:13:30 pmNo. The calibration is "hardware coded".Besides, you've obviously got calibration standards that are much more accurate than the meter is presently reading - so there's nothing to lose.QuoteTake is slowly - understand what you are doing. Do not tweak any pots or other adjustments in an attempt to correct the reading. The symptoms that you describe indicate a fault (probably leaky caps); not a calibration issue. Once you have identified and corrected the fault I wouldn't be surprised to find that the meter returns to "calibration".P.S.http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=Fluke/Fluke_8050AEdit: Also, search this forum for the writings of Dr Taylor and note the efforts taken to ensure that PCBs are clean, clean, clean.

author: james_s
author_rank: Super Contributor
timestamp: March 02, 2017, 11:27:01 pm
content: Unless somebody has already gone in there and tweaked every adjustment there is. That's the classic noob error, makes it so much less fun to repair something when you can't tell whether it's still broken or just way out of whack because the last person who worked on it adjusted everything they could find to adjust.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 02, 2017, 11:56:12 pm
content: Again, I am upset with the seller who took photos of all sides but the back, hiding that it was tampered with. He probably knew it didn't work and was way out of whack and was selling it cheap for that reason.THere are 10 electrolytic caps on the board (took it apart). 4 of which are larger (one of them read 460uf). None look bulged.

author: james_s
author_rank: Super Contributor
timestamp: March 03, 2017, 12:10:36 am
content: Welcome to eBay.The capacitors are probably not the problem, although it may make sense to replace them due to age but I wouldn't worry about that much yet. This meter was made long before the bad capacitor plague.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 12:13:59 am
content: I guess I'll try and get $10 knocked off from the seller because it wasn't fully as he described. And then part it out and try to get some money back. I imagine I could get $10-15 for the working lcd / display board -- lcd is quite decent. That way a person has a spare LCD to use and a spare display board they can play with to make a custom LED display for it. (BTW, this PCB mounted transformer looks pretty useful for another project maybe.)EDIT: Of the four larger caps one pair is 470uF 16v and the other pair 220uF 25v. They'd be easy for me to replace -- I have a local electronics shop (Mom&Pop) like 1 mile away.EDIT #2: Put an offer in on Instek GDM-8251a. I also want an HP 3478a.

author: Andy Watson
author_rank: Super Contributor
timestamp: March 03, 2017, 12:26:09 am
content: Quote from: JenniferG on March 02, 2017, 11:56:12 pmIf it helps, consider it as $30 worth of education. However, I would not give-up hope of resurrecting this meter. Look for contamination on the PCB - cap leaks ? - battery leaks ? - just water ingress ?I have had some minor success in shrinking bumps on plastic panels using a hot-air soldering iron. Keep the temperature way down low and be patient - plastic does not conduct and it takes a while for the heat to penetrate - let the surface tension pull it flat - experiment in an area of no significance. Note it's not my fault if you end-up with a homogeneous lump of squiggy grey plastic

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 12:26:47 am
content: Before you go and part it out, at least give repairing it a shot!! Can you post pics of the innards?-Pat

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 12:39:19 am
content: I don't see anything obvious -- but I'm a newb. Images are 1024 pixels wide if you open them up in another window they would probably be bigger.

author: DimitriP
author_rank: Super Contributor
timestamp: March 03, 2017, 12:44:37 am
content: Quote from: JenniferG on March 02, 2017, 11:56:12 pmSounds like "not as described" to me. Ask for $10-$15 credit and if he declines, leave negative feedback and let us know his ebay ID.Do it now, before you forget and the feedback windows lapses

author: ModemHead
author_rank: Frequent Contributor
timestamp: March 03, 2017, 12:44:57 am
content: The advice in this thread is spot-on, especially the part about not messing with the trim pots just yet.ADC input stages are very high impedance. Tiny leakage currents along with inherent parasitic capacitance can cause faulty ramp-up or ramp-down type readings. Tiny leakage currents can be caused by contamination on the PCB, possibly even inside the switches.Get yourself a good supply of strong isopropyl alcohol (IPA) and brush the board with it, both sides. Allow drying time of course. If the fault gets any better, do it again. Dunk the whole board, if necessary.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 12:48:18 am
content: Quote from: ModemHead on March 03, 2017, 12:44:57 amYeah, I had no intentions of touching those 4 adjustment pots. Was hoping that whoever had it before didn't either, but it was tampered with.. bunch of sticky residue all over the back of this unit , over the case screw hole.. large rectangle about 2 inches wide even, of old label goo. The seller didn't snap a photo of this, but all other sides interestingly.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 12:50:28 am
content: THat upper left switch. Copper sitcking on the outside. doesn't seem right. That's the only thing I noticed anyways.

author: ModemHead
author_rank: Frequent Contributor
timestamp: March 03, 2017, 12:52:49 am
content: Quote from: JenniferG on March 03, 2017, 12:50:28 amNormal. Part of the push-in/push-out mechanism.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 12:56:07 am
content: Some of those DIP are socketed. I suppose I could try to re-seat them all. But it seems more like an analog problem not digital. Many of those 4016 chips. Quad Bilateral switches. Interestingly they go for like $1 a piece, in case I part it... might be useful for a project.. dont' have any yet.I am not sure what isopropyl alcohol would do? I mean it's all soldered and alcohol only cleans the outer surface? I'm newb sorry for my questions. EDIT: oh are you saying stuff accumulated on the surface that is conductive?

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 12:59:03 am
content: You can try reseating the chips. For now, though, rather than pulling them and risking pin damage, I'd just give each of them a push down while supporting the board beneath it. You may hear/feel a slight 'click' as the chip moves in the socket. If just pushing yields no clicks or movement, perhaps pry them up *just a touch* with a small screwdriver - just till it moves. Either end should do it, it's not even necessary to lift both as just the movement should shift all the pins slightly. Then reseat them. If there's oxidation, this may break it.Does yours have the battery, or not?What does it indicate on, say, DC volts with no input and/or the input connections shorted together?-Pat

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 01:00:44 am
content: Quote from: JenniferG on March 03, 2017, 12:56:07 amOn some hi-Z meter circuits, even invisible deposits of crud can cause issues - yes, the stuff can be conductive. Perhaps megohms, or tens of megohms, but even that can throw things off.-Pat

author: ModemHead
author_rank: Frequent Contributor
timestamp: March 03, 2017, 01:02:44 am
content: Quote from: Cubdriver on March 03, 2017, 01:00:44 am+1

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 01:12:11 am
content: Quote from: Cubdriver on March 03, 2017, 12:59:03 amModel without the battery it says on the back label anyways. Don't see a battery.Set the volts to DC, 2V range. Turned it on and observed .003. A few seconds later it was .0115.Then over time:.0104 (15 sec).0098 (30 sec).0093 (1 min).0090 (1:15 min).0086 (1:30 min).0084 (1:45 min).0083 (2 min).0080 (2:15 min).0077 (2:30 min)I suppose it might slowly keep going down but I turned it off at this point. This is with no probes plugged into the unit.

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 01:16:33 am
content: Just for grins, leave it plugged in and on for a while. Who knows how long it's been off - perhaps the power supply filter caps need to re-form.-Pat

author: guenthert
author_rank: Frequent Contributor
timestamp: March 03, 2017, 01:20:02 am
content: Quote from: DimitriP on March 03, 2017, 12:44:37 amWhoa, slowly there. Just because there was no picture of the rear, doesn't mean it wasn't intentionally left out. Just because there's no calibration sticker, doesn't mean it has been opened. Just because it has been opened, doesn't mean it has been tempered with (many of us are curios, aren't we?).Jennifer, you mentioned you're newbie. Well, most of us are to some degree and we all make occasionally a silly mistake. I'm not familiar with the 8050, but I see a 'Rel' button there and simply have to ask, whether the meter has been zero'ed or is displaying the offset to an earlier stored value.(other than that, I'd think $20 would be a good price for a 'for parts' DMM as well -- for working meters I paid considerably more)

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 01:20:47 am
content: Anyone know the best deal on ebay for a large electrolytic capacitor assortment? I'd like as many as possible in as many possible capacitances. I really don't have many now and don't want to pay huge sums for single caps from digikey and mouser on a per project basis. I do need 220uf and 470uf for this meter , so those would be nice to have in an assortment.

author: james_s
author_rank: Super Contributor
timestamp: March 03, 2017, 01:22:33 am
content: Don't part it out, there isn't really much in there that's useful as parts for anything but another 8050 meter. The isopropyl cleans contamination off the PCB, meters are very sensitive to anything even slightly conductive, even fingerprints on the board can cause problems. I like the internal design, everything is nice and spread out, discrete parts, nothing unobtainable, I think it should be fairly straightforward to repair. Did you find a copy of the service manual and schematics? Should be available online somewhere.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 01:22:52 am
content: Quote from: guenthert on March 03, 2017, 01:20:02 amI know what you are saying, but there is a big bump on the front he didn't mention and it doesn't show up in his photos. the other stuff is speculation. But reasonable speculation since he didn't point out the dimple.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 01:24:32 am
content: Quote from: james_s on March 03, 2017, 01:22:33 amYes I have the manual. I am not smart enough to troubleshoot this. I got this meter as my "first *real* meter" for the LAoE course I was about to start. (After I finish that course, maybe I'll be smart enough to troubleshoot). I put an offer in for an Instek 8251A a bit ago. Also have a bid on a 3478a.

author: james_s
author_rank: Super Contributor
timestamp: March 03, 2017, 01:27:50 am
content: Just set it aside for now. You really need to have at least one fully functional meter in order to troubleshoot other equipment. I'd try washing the board with alcohol first but don't do anything too drastic.

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 01:29:01 am
content: Quote from: JenniferG on March 03, 2017, 01:24:32 amBah! We all had to start somewhere. And you have the lot of us (lord help you) to assist in troubleshooting.And when it rains, it pours - based on your bids nd offers, you'll be up to your eyeballs in meters in the near future.-Pat

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 01:33:20 am
content: I'd like two bench meters and one decent handheld with 6000 count or better , preferbly 20k count.. like an 8060a.Right now I have a reliable cheapy 2000 count handheld that works better than this fluke at least.HOw many meters do you guys have? giggle.

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 01:38:54 am
content: Quote from: JenniferG on March 03, 2017, 01:33:20 amWorking, or in total? I'm almost afraid to count!-Pat

author: Cerebus
author_rank: Super Contributor
timestamp: March 03, 2017, 01:56:36 am
content: Quote from: JenniferG on March 03, 2017, 01:12:11 amThat many be quite normal, I don't know this meter well enough to be sure. Try it with a dead short on the inputs. If it reads zero immediately or almost immediately then what you're seeing is the result of a really high impedance input just picking up random cruft or a bit of leakage current across the board or even the input jack. The input impedance on many meters can be in the order of 1012ohms on any ranges that don't have a resistive divider in front of the input amplifier, on an old meter it's often the 2V or 3V range that is the 'native' range of the ADC and has the high-Z input. At 1012ohms input impedance, to get the kind of 0.01 V readings you're seeing would require a princely 1fA , or 10-15A, or 6250 electrons per second.

author: george.b
author_rank: Frequent Contributor
timestamp: March 03, 2017, 01:59:45 am
content: Ah, the 8050A isn't even that complicated a beast!As others pointed out, leakage currents, high Z etc etc... here's what I would do for starters: if the meter isn't as advertised, I'd file a claim for partial refund. With the partial refund money, I'd buy a can of contact cleaner spray and clean up those range switchescould be as simple as that!As for how many meters, I only have my 8050A and a Fluke 27. Thinking about getting one of those UT136B cheapies.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 02:00:01 am
content: I've never shorted the inputs of a volt-meter -- almost afraid to honestly lol. I have shorted the inputs on an ohm-meter , lots of times, for continuity checks.

author: eugenenine
author_rank: Frequent Contributor
timestamp: March 03, 2017, 02:01:44 am
content: I wouldn't part it yet. I was going to suggest going to harbor freight or a hardware store and getting the cheapest dmm they sell to use to troubleshoot this one, but since you already have one your a step ahead there. Download the #4 maintenance manual from the link posted in the first page of the thread an go through as many checks as you can with the equipment you have to see if you can find any issues.I don't believe you have the battery option otherwise there would be a charge light beside the power switch on the front. The back cover could have been swapped with another so you never know if its the original or not, I wouldn't trust it.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 02:03:15 am
content: Quote from: george.b on March 03, 2017, 01:59:45 amYeah show's how stupid I am hah. All I could do is pull caps and measure microfarads and replace. Reseat chips. Clean board with alcohol. Test each and every resistor to make sure it has right resistance. That's about all I could do right now with my experience.Quote from: george.b on March 03, 2017, 01:59:45 amTHanks. I'll try cleaning it. I do have a couple cans of different contact cleaner. One is the expensive de-oxit I used to clean tube amp contacts.

author: kcbrown
author_rank: Frequent Contributor
timestamp: March 03, 2017, 02:04:59 am
content: Quote from: JenniferG on March 03, 2017, 01:33:20 amOne less than I should have.That statement is a constant, by the way.

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 02:07:09 am
content: Quote from: JenniferG on March 03, 2017, 02:00:01 amIt won't hurt anything - perfectly safe to do, and actually necessary to zero hi-z meters. Try it, and see if your count goes to zero or nearly so, and becomes stable there.-Pat

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 02:11:55 am
content: Interesting, I left it on a while and it's reading in the correct range now. got close to 22 ohms for 22 ohm resistor. 6v is close as well.Should I go ahead and replace all the electrolytic. I mean will I have problems with it in the future warming up? I'll do the isopropyl alcohol cleaning thing along with contact cleaner for switches at least. Maybe it'll be a decent meter.

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 02:12:55 am
content: Quote from: JenniferG on March 03, 2017, 01:33:20 amI probably should not have done it, but I counted. Readily accessible and visible:Functional: 11Thought to be functional, but not fully tested: 1Unknown or in the repair queue: 24And yes, I do have active evilBay searches for some others that I don't yet have...-Pat

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 02:13:43 am
content: Quote from: Cubdriver on March 03, 2017, 02:07:09 amHrm, is my meter working at least close to correct now because I did the short thing on dc inputs? I can't recall if I did that before or after I started getting more reasonable readings.

author: med6753
author_rank: Super Contributor
timestamp: March 03, 2017, 02:17:08 am
content: Jennifer, the symptoms you describe look very much like board contamination. I just went thru this very issue with the little brother 8010A which I just recently outlined in the TEA and in fact you commented on it.Get some IPA, distilled water, and a toothbrush. Scrub down both sides of the board with the IPA, including the selector switches. Try NOT to turn the trim pots with the brush. Let it dry for a few minutes then follow it up with a scrubbing with the distilled water. Again, don't turn the trim pots.Now you need to bake the board at no more than 150 degrees F (65 C) for a few hours. Don't get the bake too hot or you'll damage plastic. And if you can separate the LCD from the main board then go ahead and do that. The LCD should not go thru the bake cycle.

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 02:20:45 am
content: Quote from: JenniferG on March 03, 2017, 02:11:55 amIt may have been noise on the power supply lines. Let it cook for a while more.If it has been sitting off for a long time, the electrolytics can lose capacity. If they still have sufficient electrolyte, they can re-form, and potentially be fine for a long time. It likely wouldn't HURT to change them (if you do this, get good ones, not evilBay specials of unknown pedigree). I'd be inclined to let it run for a bit, then leave it off for a few days and fire it up again. If it settles in a few minutes, I'd leave it alone, parts-wise.If you do the isopropyl clean, get it from a hardware store or HD or the like - don't user rubbing alcohol (which ismostlyisopropyl), because it usually has oils and dyes and whatnot in it - NOT something you want to put on a hi-Z board... Quite honestly, if it settles down and seems to be accurate, I wouldn't even do that - if it works, leave it be.-Pat

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 02:21:15 am
content: Quote from: med6753 on March 03, 2017, 02:17:08 amI could stick the board under a box fan for a few hours. That really dries stuff out. When I craft stuff, paint takes like 5-10 mins to dry -- without sometimes a couple hours. Yeah of course I'll be careful not to bump the calibration pots--I appreciate the warning though as I am a newbI see the gear needed to calibrate these.. it's pretty demanding

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 02:23:44 am
content: Quote from: JenniferG on March 03, 2017, 02:13:43 amI doubt shorting them changed its operation - that's simply a way to make sure that the input is at zero - if the meter is climbing or showing voltage with the inputs shorted, then you know that something is amiss inside, whether it be adjustment or offset due to leakage.-Pat

author: eugenenine
author_rank: Frequent Contributor
timestamp: March 03, 2017, 02:35:18 am
content: Ohh, you just got it today, did you just bring it into the house and unbox and try it out? Its probably sat out in the cold mail truck for a while and needs to acclimate to room temperature.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 02:39:45 am
content: Quote from: eugenenine on March 03, 2017, 02:35:18 amYeah it was sitting out on the porch in the cold for a few hours too.Well thanks guys for everything. I got it all back together again, enclosed in its case. Leaving it on for the next several days. (Maybe it's a cap reforming thing whatever that is that Cubdriver helped me with.) Then I'll compare to handheld. Then probably go to local electronics store and buy a couple resistors.. like 1k and 10k. Have them measure those two resistors there on their 6.5 (maybe even 7.5) calibrated meter and record values for me. THen I'll compare at home with the FLuke. I'll report back.I also bought an AD584L (sp) 2.5/5/7.5/10 reference voltage pcb from china (with actual recorded values allegedly) .. I'll compare my voltage against that after I get it. I'll probably be comparing my AD584L against the meter at the electronics shop as well and record values.EDIT: gonna clean up the case now with some goo gone.

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 02:43:20 am
content: I think we may have a budding volt nut on our hands here!-Pat

author: med6753
author_rank: Super Contributor
timestamp: March 03, 2017, 02:46:33 am
content: Quote from: JenniferG on March 03, 2017, 02:21:15 amIf you decide to clean the board you really should bake it at low heat to insure ALL the water is evaporated. A toaster oven set at low heat is perfect for the job and the 8050 circuit board will fit.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 02:56:40 am
content: I have the nicest toaster oven built. The Breville. So yeah I could set it that temp (or even lower) for hours and it will stay putFor now, I am just going to take Cubdrivers advice and let it burn in for several days and see how works from then on.

author: Cubdriver
author_rank: Unknown
timestamp: March 03, 2017, 02:57:27 am
content: Quote from: med6753 on March 03, 2017, 02:46:33 amIf you do hit it with distilled water, I'd actually do another IPA rinse afterwards - the IPA will absorb most of the water and wash it away, and the residual IPA will evaporatemuchmore readily than water will. Oh, and if you have a gas oven, make sure that most of the alcohol fumes are gone before baking it.-Pat

author: eugenenine
author_rank: Frequent Contributor
timestamp: March 03, 2017, 03:22:36 am
content: Quote from: JenniferG on March 03, 2017, 02:39:45 amThis is probably the issue. When you bring it in from cold outside to warm inside it need time to warm up and adjust to the temp. Working at a pc shop back in the day, hdd shipments would come in recommending waiting 48 hours before powering up.

author: james_s
author_rank: Super Contributor
timestamp: March 03, 2017, 05:24:41 am
content: Quote from: JenniferG on March 03, 2017, 01:33:20 amI have a Fluke 87 handheld, a Fluke 45 bench meter, and an old Keithly bench meter with a nixie tube display, the latter mostly because it looks cool, I rarely use it. Oh and I have one of those cheap Harbor Freight meters I keep in my car. I've never found a need for anything fancier than these, for most things 3.5 digits are plenty accurate, 4 digit is nice to have, more than that is specialty territory. Unless you have specific needs or a particular fetish with extreme precision there are other areas where the money is better spent. A very well made dependable meter is more useful than a zillion digits.

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 06:12:57 am
content: Quote from: james_s on March 03, 2017, 05:24:41 amWas thinking an HP 3478a. More digits than I'd ever need and I heard it has very good precision and built well. Hopefully I can solder another battery in parallel and replace the other without losing calibration though. Hoping to pick one up for about $125 if possible. I think that's a really good. I suppose I can use a cheap $10 meter for continuity checks.

author: kcbrown
author_rank: Frequent Contributor
timestamp: March 03, 2017, 07:06:44 am
content: Quote from: james_s on March 03, 2017, 05:24:41 amA fetish with extreme precision? More than 4 digits is specialty territory???Sacrilege!!Everyone needs an 8.5 digit multimeter. How else are you going to tell if your 7.5 digit multimeter is accurate??

author: JenniferG
author_rank: Frequent Contributor
timestamp: March 03, 2017, 07:14:47 am
content: I suppose a high digit count and good frequency counter is great for tweaking the pots for 1v / octave VCO's.

author: james_s
author_rank: Super Contributor
timestamp: March 03, 2017, 08:39:47 am
content: Quote from: kcbrown on March 03, 2017, 07:06:44 amWell I didn't say there was anything wrong with extreme precision, I just recognize that I myself rarely need more than 2-3 decimal places, for the stuff I do anything more is just superfluous data that I round off in my head. That doesn't mean there are not perfectly valid needs for higher precision, I just haven't generally encountered them. I don't care if the power rail in something I'm working on is 3.30V or 3.2985372V, it's not going to make a difference to circuit operation.It's also important to differentiate between accuracy and precision.

author: kcbrown
author_rank: Frequent Contributor
timestamp: March 03, 2017, 10:08:01 am
content: Quote from: james_s on March 03, 2017, 08:39:47 amIt was a joke, son, a joke! (said in my best Foghorn Leghorn voice...)I'm a big fan of using the right tool for the job myself, and agree that most jobs aren't going to require a great deal of precision.It's a bit of a trade off as to how much precision to get. If you have extra precision, you'll have lower precision requirements covered automatically, but if all you have is relatively low precision equipment then you probably won't be able to perform work that requires more, at least not without a great deal of ingenuity. So I suspect you're best off getting as much precision as you can afford and that you think you might ever use (but see below).For myself, I suspect 5.5 digits is sufficient for anything I might do. So my Instek 8251a and Amprobe 140 should provide enough for even the most precise work I might find myself doing.It becomes trickier when one is on a substantially restricted budget. Then you might have to give up a little precision for one thing just to be able to acquire some other capability at all.It's impressive how much capability you can get for relatively little money these days...And yes, it is indeed important to be mindful of the difference between precision and accuracy. Note, however, that precision limits usable accuracy, which is why higher precision equipment generally has better accuracy specs as well (when calibrated, of course).(Sent with Tapatalk, so apologies for the lackluster formatting)

author: eugenenine
author_rank: Frequent Contributor
timestamp: March 03, 2017, 12:15:10 pm
content: I don't know what you all are working on, I find my Simpson 260 precision to me enough 99% of the time

author: rrinker
author_rank: Super Contributor
timestamp: March 03, 2017, 02:49:46 pm
content: Something for testing the meter would be a good calibrated reference source. I was going to suggest the one I have, but it appears to now be discontinued. I have the DMMCheck-Plus from Malone which has AC and DC calbibrated voltage and current references plus a calibrated set of precision resistors. Not a replacement for actually sending a meter out for calibration but it's all precision parts and he supplies a cal sheet, and also free recal for the first 2 years.Bummer this was discontinued, nice to have it all in one instead of a bunch of different devices to manage.