Author Topic: Repairing my old multimeter...  (Read 17263 times)

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Offline pmrlondon

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Repairing my old multimeter...
« on: April 24, 2011, 01:30:17 pm »
I am about to buy a new multimeter, but am hoping, once I have it, that I can also repair my old one. The old one appears to have two faults, one of which I have an idea as to what it might be.

The meter is a Precision Gold WG021 - I've had it 15 years and it gave me no significant problems until it stopped working four years ago.

The main fault: the meter seems to be unreliable on AC - giving strange, stuck readings. As AC/DC selection is by a mechanical switch, I suspect either the switch or some of the diodes may have gone wrong. There were stuck readings on most ranges before, but I found a broken resistor and soldered it back together. Now it works OK on DC but not on AC.

The odd fault I haven't a clue about... on the 4000M? range, shorting the probes together gives a reading of 19. On the lower ranges, it reads 0, or on 400?, 0.2 or so, so the reading of 19 has to be something in the meter only applying to that range. (the meter is manual ranging, except on Hz)

Is this meter likely to be worth repairing? Does anyone on the forum have an idea as to what these faults might be?
 

Offline saturation

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Re: Repairing my old multimeter...
« Reply #1 on: April 24, 2011, 02:33:32 pm »
That brings up an interesting question: when should we retire old test gear?  As EE we can maintain our gear far longer than consumers, and even upgrade them to better specs.  In multimeters some sections can be obsolete, like AC, while the DC or ohms is still good.

Thus, does an EE or technician really have to buy new gear if they can maintain old ones, if its cost effective? [ Finding parts in your country versus buying a new item.]

I don't know this model MM, but I presume its digital.  Does it have CAT ratings for safety?  Does it use sheathed banana jacks?  Is its rated accuracy on AC less than 1% on all ranges? Is it true RMS?

If the answer is no to any of them, the meter is obsolete but its still useful if you only use line voltage.  But for tasks requiring measuring AC voltages at many frequencies or wave-shapes, the meter isn't capable.

One issue is cost, if you can afford a new DMM its better to upgrade for the safety features of CAT ratings, even if you can repair this DMM.  One can still buy a meter with similar specs of your 15 yr old DMM for much under $US50 and CAT rated for safety.
« Last Edit: April 24, 2011, 02:39:16 pm by saturation »
Best Wishes,

 Saturation
 

Offline Kiriakos-GR

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Re: Repairing my old multimeter...
« Reply #2 on: April 24, 2011, 05:12:00 pm »
Hi Phil ,  the link of your web page is not set correctly on your local profile, but i found my way.  :)

Quote
I am about to buy a new multimeter, but am hoping, once I have it, that I can also repair my old one.

What do you have in mind ?

The true good ones, that can be used as true reference , they cost some serious money. 

 

Offline pmrlondon

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Re: Repairing my old multimeter...
« Reply #3 on: April 24, 2011, 07:40:49 pm »
My (already chosen) new meter will be an Amprobe 37XR-A. I will be getting it in a few weeks.

The Precision Gold WG021 is digital, 4000 count. No CAT ratings are marked on it at all. The jacks are sheathed up to the height of the contact. Not true RMS and not sure of the accuracy as I haven't seen the manual for a while. HRC fuses, 500mA and 20A, and there is a PTC in it. It has the virtually useless hFE function, and a body L/C socket rather than being able to measure inductance and capacitance with the probes. Manual ranging, except on Hz.
 

Offline saturation

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Re: Repairing my old multimeter...
« Reply #4 on: April 24, 2011, 10:57:08 pm »
Sounds like time for upgrade and the Amprobe is a fine meter.

One thing with instruments is a matter of trust and daresay, faith.  Sure it works now, but when will it fail? So while repairs can revive an old friend, it may not be the DMM you'd want to take to a difficult job site or underneath a tight crawlspace to measure something and then not trust what you're seeing.




Best Wishes,

 Saturation
 

Offline House91320

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Re: Repairing my old multimeter...
« Reply #5 on: April 25, 2011, 01:01:07 am »
pcb pics pleas
 

Offline pmrlondon

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Re: Repairing my old multimeter...
« Reply #6 on: April 25, 2011, 07:38:01 am »
Indeed, the Amprobe will be the one that gets used most. Thinking of possibly hanging on to the PG for those situations where two meters are useful at the same time. The Amprobe will be the one that travels, often to awkward corners of caravans and so on.

I fully intend to at least post pics of the inside of the PG before I start doing any work on it. If I do manage to restore it, I will say what I found wrong.

If my need for an additional meter gets really serious, I intend to save up for possibly a Gossen Metrawatt. I have found few suppliers over here, carrying very few models, but I would have a further look and maybe even check prices in mainland Europe.
 

Offline saturation

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Re: Repairing my old multimeter...
« Reply #7 on: April 25, 2011, 10:02:08 am »
Yep, the way Dave and jahonen use it, it speaks for itself.  Its got many unique features good for EE class of use. 

Indeed, the Amprobe will be the one that gets used most. Thinking of possibly hanging on to the PG for those situations where two meters are useful at the same time. The Amprobe will be the one that travels, often to awkward corners of caravans and so on.

I fully intend to at least post pics of the inside of the PG before I start doing any work on it. If I do manage to restore it, I will say what I found wrong.

If my need for an additional meter gets really serious, I intend to save up for possibly a Gossen Metrawatt. I have found few suppliers over here, carrying very few models, but I would have a further look and maybe even check prices in mainland Europe.

Best Wishes,

 Saturation
 

Offline Tony R

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Re: Repairing my old multimeter...
« Reply #8 on: April 25, 2011, 01:31:20 pm »
My policy is to get flukes with a "lifetime" warranty, which basically means at least 10 years. Once it is up, use it until it dies, but nothing where safety becomes an issue on and nothing that requires that much accuracy. don't stick any more money into it just replace it when it dies.

My thoughts are if fluke wont support there product anymore, there must me reasons why...

Being this DMM has not a cat rating on it and is not fully working, it would be fine for measuring some stuff in it, but i wouldn't stick to much cash into it and I wouldn't test your outlets with it.

Plus if you do the math, spend 300 dollars or so on a nice fluke, it will last 10 years, your spending about 30 bucks a year on a DMM, Not to bad really...

I would think about retiring it.
Tony R.
Computer Engineering Student
Focus: Embedded Assembly Programming, Realtime Systems,  IEEE Student Member
 

Offline saturation

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Re: Repairing my old multimeter...
« Reply #9 on: April 25, 2011, 05:22:08 pm »
I think robustness plays a great deal too in a DMM's success or long service life.  Its made Fluke's rubber sleeve so successful.  Although the 80 series is only IP 30 rated versus 'rugged' being roughly IP 67, its design does take common field ab/use well [ table drops, extremes of climate: hot, cold, humidity, survives rain but needs to be dried before use].  Many DMM in Dave's review survive a table drop, but real life drops happen very often, so not sure if the criteria is one drop, or drop repeatedly at that height.  Since the 80 series has been around over 20 years, its reputation for physical abuse is well known.
Best Wishes,

 Saturation
 

Offline Kiriakos-GR

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Re: Repairing my old multimeter...
« Reply #10 on: April 25, 2011, 11:40:58 pm »
If some one could speak about DMM abuse , this one could be only an electrician,
by owning the Fluke 28II , I will not have to worry about falling from a ladder . ( not me, the DMM )  :D

At the soft handed professionals, that do only electronic repairs on bench ,
any DMM it will survive from falls ( 1 meter drop ) , but I can not tell the same about the high voltage of a fly-back  ;)  
 

Offline tekfan

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Re: Repairing my old multimeter...
« Reply #11 on: April 25, 2011, 11:51:11 pm »
If some one could speak about DMM abuse , this one could be only an electrician,
by owning the Fluke 28II , I will not have to worry about falling from a ladder . ( not me, the DMM )  :D

At the soft handed professionals, that do only electronic repairs on bench ,
any DMM it will survive from falls ( 1 meter drop ) , but I can not tell the same about the high voltage of a fly-back  ;) 

Don't mess with flybacks. You'll almost certanly destroy your meter unless you have a high voltage divider probe designed to handle 40KV+ voltage spikes.

Recently I saw a bus/car repair technician with a Fluke 123 scopemeter. It was completely dirty (black, not yellow). It must have had a very hard life but it still worked as it should.
One can never have enough oscilloscopes.
 

Offline Cj1corbystarlet

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Re: Repairing my old multimeter...
« Reply #12 on: April 26, 2011, 04:21:16 am »
I have a Fluke 75mk3 from memory, as a Electrician it gets hammered every day at work, 

After 12 years of daily service the battery went flat, replaced the battery and all is good.

Cant beat a good Fluke.

regards
Ben
 

Offline Kiriakos-GR

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Re: Repairing my old multimeter...
« Reply #13 on: April 26, 2011, 01:34:42 pm »
unless you have a high voltage divider probe designed to handle 40KV+ voltage spikes.

Well i do have it , so to feel complete .  :)




 

Offline Kiriakos-GR

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Re: Repairing my old multimeter...
« Reply #14 on: April 26, 2011, 01:36:47 pm »
After 12 years of daily service the battery went flat, replaced the battery and all is good.



Hi Ben , I bet that in your message,  the correct word are months instead of years   ;D

My regards to you too.

« Last Edit: April 26, 2011, 01:39:03 pm by Kiriakos-GR »
 

Offline saturation

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Re: Repairing my old multimeter...
« Reply #15 on: April 26, 2011, 02:04:10 pm »
12 years, if true is truly impressive! Given what I've seen of electricians and service folks who use Flukes, what really kills DMMs is more likely physical abuse than electrical mishap; the latter can happen and lead to injurious consequences for the user but its rarer than dropping a DMM from a ladder 12+ feet off the ground, into a concrete walkway.


After 12 years of daily service the battery went flat, replaced the battery and all is good.



Hi Ben , I bet that in your message,  the correct word are months instead of years   ;D

My regards to you too.


Best Wishes,

 Saturation
 

Offline Cj1corbystarlet

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Re: Repairing my old multimeter...
« Reply #16 on: April 26, 2011, 02:59:43 pm »
I'm serious yes my Fluke is 12 years old  :)

I do have to admit i work on industrial machinery and control panels, so it does not get abused, but the Fluke is on her 3rd set of probe leads.

I must get a HV divider probe, as i'm working on some rather interesting HV projects at home........

Ben
 

Offline saturation

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Re: Repairing my old multimeter...
« Reply #17 on: April 26, 2011, 07:15:42 pm »
That's great, but did you only change the battery once in 12 years?

I'm serious yes my Fluke is 12 years old  :)

I do have to admit i work on industrial machinery and control panels, so it does not get abused, but the Fluke is on her 3rd set of probe leads.

I must get a HV divider probe, as i'm working on some rather interesting HV projects at home........

Ben

Best Wishes,

 Saturation
 

Offline Kiriakos-GR

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Re: Repairing my old multimeter...
« Reply #18 on: April 26, 2011, 09:08:39 pm »
I'm serious yes my Fluke is 12 years old  :)

Ben


From what you typed , it sounded like that your battery lasted 12 years in it ..  :)
 

Offline Cj1corbystarlet

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Re: Repairing my old multimeter...
« Reply #19 on: April 27, 2011, 10:59:57 am »
Yeah sorry guy's my initial post was a little confusing (Even to me ! :-[ ), First battery did last about 8 years, second one about 4 years, and its got a 3rd fresh battery battery in it now.

I must pre-read my posts before hitting the go button.
Ben
 

Offline Kiriakos-GR

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Re: Repairing my old multimeter...
« Reply #20 on: April 27, 2011, 11:20:50 am »
No problem mate.  :)

Its good having you around.
 

Offline vk6zgo

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Re: Repairing my old multimeter...
« Reply #21 on: April 27, 2011, 04:57:00 pm »
I think people get a bit overwrought when it comes to CAT ratings & the like.

 Out of the huge numbers of Radio & TV Transmitter Techs,EEs & Electricians that over many years have used such things as AVO model 8 multimeters,Fluke 77s,the early Beckmans,etc,the number of people injured due to deficiencies in their meters is vanishingly small.

How many times would the average user really need "true RMS"?
If you need to worry about the waveshape,use an oscilloscope!

OK,if I was buying a new DMM,I would go for all this stuff,but my Fluke 77 still
works,& doesn't have the strange habits  of some cheap replacements.

Dear old UNI-T ! great if you have plenty of spare time to wait for it to deign to give you a reading.Or,I love the way the resistance ranges go inaccurate with a dying battery,BEFORE the low batt indication comes on!

Another cool thing is the way the thing turns itself off when you are in the middle of a reading!'Even the new Flukes do this!(Although you can disable it).

The 77 will turn off if there has been no measurement activity for a while,but not
bang in the middle of a reading.


GRRR.VK6ZGO
 

Offline Kiriakos-GR

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Re: Repairing my old multimeter...
« Reply #22 on: April 27, 2011, 06:58:39 pm »
Another cool thing is the way the thing turns itself off when you are in the middle of a reading!'Even the new Flukes do this!(Although you can disable it).

The 77 will turn off if there has been no measurement activity for a while,but not
bang in the middle of a reading.


GRRR.VK6ZGO

+ 1000 for this info ..  It happened also to me ( 28II) even in diode mode ( the thing turns itself off ) ,
and I was working with it, testing some micro buttons , and the first though was that it died in my hands .

Why in earth to ignores that there is activity , and does not cancel the damn inner timer ?  

Either way brother,  you need an 28II , or else you will continue to feel like a poor relative with a 77 at hand.  ;)  
No matter the small nags about the 28II it is a killer .
The No1 armored multimeter for out door use , and modern and all.  

About the Dear old UNI-T , yes they are a bit slow , but is the best choice for starters ,
price / performance ,  so your nags about it , is not that justified.
But you are correct up to a point.

 
« Last Edit: April 27, 2011, 07:05:39 pm by Kiriakos-GR »
 

Offline Ernie Milko

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Re: Repairing my old multimeter...
« Reply #23 on: April 27, 2011, 07:01:13 pm »
To answer the OP's question. Yes. I think you should have a look at repairing your DMM. Those old Precision Gold meters (Maplins, I presume?) were pretty good.
Chances are it's just dirt on the switch contacts. Take the meter apart and clean them with a cotton bud and some IPA.
If it's not the contacts, it could be a dry joint. Check the meter over in bright sunlight.

In this day and age, where everyone throws everything away and repairs nothing, and people upgrade every other week to the latest iphone, I think people should be positively encouraged to repair things.

And I agree 110% with VK6ZGO, above. VK6ZGO struck a chord and made me post to a thread I've read but wasn't going to post to.
Everyone gets far too excited about CAT ratings and true RMS.
When I first started (work I mean, not hobby tinkering) 30 years ago, meters were naff-all rated. And true RMS meters were made by Fluke and Bill and Dave, lived in the lab and cost five grand, and some.

And there are true RMS meters and true RMS meters. My Fluke 87IV can measure the AC and DC components of a non-sinusoidal waveform.
Many true RMS meters (such as the Fluke 179, and probably the Fluke 87V, although I haven't checked; before all you 87V fanboys jump down my throat) can only measure the AC component.
For, as it were, true, true RMS measurements, you need a meter with a thermal converter, such as a Fluke 8920, or an 8520.
And, as VK6ZGO says, if your waveform is that distorted; you're probably better off with a scope.
 

Offline Kiriakos-GR

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Re: Repairing my old multimeter...
« Reply #24 on: April 27, 2011, 07:15:59 pm »
before all you 87V fanboys jump down my throat


 :D :D :D :D

I loved the all message , but this part mostly.

I stand in the middle, and love and keep anything useful , no matter the manufacturing date.
But since the time that the transformers ( made of copper ) had almost stopped to exist in any modern PSU,
the need for True RMS DMM become an necessity .
I can found and many other examples , but I do not need any analog fanboys to jump down on my throat .  ;) 
 


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