Fluke 8050A -- Received it today

[guenthert]

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.

Sounds 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

Whoa, 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)

[JenniferG]

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. 

[james_s]

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.

[JenniferG]

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.

Sounds 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

Whoa, 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)

I 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.

[JenniferG]

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.

Yes 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.

[james_s]

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.

[Cubdriver]

Yes 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.

Bah!  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

[JenniferG]

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.

[Cubdriver]

HOw many meters do you guys have? giggle.

Working, or in total?  I'm almost afraid to count!

-Pat

[Cerebus]

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?

Model 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.

That 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 10¹² ohms 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 10¹² ohms 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.

[george.b]

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 switches could 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.

[JenniferG]

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.

[eugenenine]

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.

[JenniferG]

Ah, the 8050A isn't even that complicated a beast!

Yeah 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.

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 switches could 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.

THanks.  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.

[kcbrown]

HOw many meters do you guys have? giggle.

One less than I should have.

That statement is a constant, by the way.   

[Cubdriver]

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.

It 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

[JenniferG]

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.

[Cubdriver]

HOw many meters do you guys have? giggle.

I probably should not have done it, but I counted.  Readily accessible and visible:

Functional: 11   

Thought to be functional, but not fully tested: 1

Unknown or in the repair queue:  24 

And yes, I do have active evilBay searches for some others that I don't yet have...   

-Pat

[JenniferG]

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.

It 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

Hrm, 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.

[med6753]

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.

 

[Cubdriver]

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.

 

It 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 is mostly isopropyl), 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

[JenniferG]

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 back cycle.

I 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 newb   I see the gear needed to calibrate these.. it's pretty demanding

[Cubdriver]

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.

It 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

Hrm, 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.

I 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

[eugenenine]

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.

[JenniferG]

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.

Yeah 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.