Fix a DMM?

[Phil_S]

I've got a problem with my Triplett 9045. The meter seems to work OK for everything but Ohms. I had an "incident", measuring ACV when there was a spark. When I turn it to autorange Ohms, it reads 258K, nothing connected to it. Shifting to manual it reads 10M or 1M. This is clearly weird.

I tried to contact Triplett. It's been weeks and no reply. Anyone out there who fixes test equipment?

Here is some stuff to look at. A layout, schematic, and a picture of the board showing the 4x 2.5M resistors that are between the probe and the CPU of this thing. The 4x 2.5M all meter good and the string is 10M. There is a thing between these 4 resistors, and I don't know what it is. It looks like a cap (orange) and the schematic labels it Rp PTC. The Rp meters at 1.2K, but seems to be invisible when I add it to the string of 4x 2.5M. Obviously, I think the problem is here, but I really feel like a fish out of water.

Any suggestions? Thanks.

[selloutrr]

most calibration companies also offer repair services. I'd suggest looking into this avenue since the meter will need to be calibrated after it's operational. they usually charge $65-100hr to repair, and have a flat rate to calibrate based on the piece of equipment.

Opt 2

If you try to fix it yourself, divide it into groups an based on which position the function selecto is in and trace back from that. Since ohms is your issue set it to ohms and test continuety draw out the schematic and layout and then test values and see what's a miss. if you have in-ciruit parts testers it'll go faster. look for burn marks or things that are a miss.

[Cliff Schecht]

Unfortunately a lot of times it isn't worth the time/cost it takes to fix a DMM. I blew up a Fluke that wasn't mine looking at a beefy transformer. Turns out they mean don't go over 1000V peak-peak, not RMS hehe.

[Phil_S]

OK, what I thought. This is, at retail, a $78 meter that I got for under $50 on eBait a couple of years ago. No calibration, no fix. I attempted a feeble diagnostic on it and got nowhere. It appears to have continuity all the way to the CPU chip. I can't see any burn marks of any kind. So, I don't think this is something to pursue. I'll keep it for the other functions. I've got 3 other meters, but this is the one I liked best. Maybe I'll replace it with a Fluke.

Thanks very much for your help!

[selloutrr]

You'll be very happy with a Fluke

[Phil_S]

Yeah, that would more properly be "another Fluke". I've got an old bench meter 8600A. It's not as handy as a hand held, but it's a solid meter.

[marcoloco961]

Unfortunately a lot of times it isn't worth the time/cost it takes to fix a DMM. I blew up a Fluke that wasn't mine looking at a beefy transformer. Turns out they mean don't go over 1000V peak-peak, not RMS hehe.

Ouch! I had a borrowed meter eaten by a nasty microwave transformer years ago. Had a tough time finding a exact replacement, but finally did, complete with two sets of leads and a carrying case. Got me out of dutch.

Since then I always try to test unknown transformers with a 12VAC/wall wart transformer on the primary and multiply by 10

[Richie]

you would think it would be fused. The cheaper ones just pop..
Like many here, i don't know how many i have gone through.

[dynaman]

Haha, I'm the worst of the lot. I buy about one per year. I drop them, drag 'em by their leads, balance loaded amps on them. I'd prolly get more use out of a block of wood for a fraction of the cost.

Mine usually cook cuz I'm always forgetting to switch the meter's function when I change tasks. Auto-ranging only gets ya so far...

My present meter was an emergency purchase from Sears. I paid about $35 and I'm stoked that it measures very small capacitance values and its really compact. I picked up thousands of small caps a while back and was never able to accurately measure them until now.

Check out Sears' website and do a search for multimeters. You'll be amazed at how many different meters they offer!

[Phil_S]

It turns out that I'm a sucker for the bargain DMM. I got the last Amprobe 105 TRMS from the clearance section with a 7% off coupon for $48.30 shipped. I think they were retailing for $99+ s/h. I figure I got it roughly at dealer cost or maybe even a few bucks less.
http://www.testequipmentdepot.com/ampro ... series.htm

[M Fowler]

I have Fluke and Fieldmeter but prefer the el cheapo most of the time.

Must be because that was all I had for years.

Still have my cheap analog meter that my furnance guy had to borrow one cold winter day when servicing my furnance. I told the guy the problems sounds to me like poor draining as you could hear the pipes gurgle but he insisted on metering every danm thing while going through it cycle and the analog was the only meter to use for that. It was poor draining so we added blocks under the PVC pipes to get the proper angle. This was a no charge service call anyway.

Mark

[Structo]

It turns out that I'm a sucker for the bargain DMM. I got the last Amprobe 105 TRMS from the clearance section with a 7% off coupon for $48.30 shipped. I think they were retailing for $99+ s/h. I figure I got it roughly at dealer cost or maybe even a few bucks less.
http://www.testequipmentdepot.com/ampro ... series.htm

Amprobe must have bought out Meterman.
I have a Meterman 37XR that is identical to the Amprobe 37XRA

As far as I'm concerned my Meterman is every bit as good as a Fluke.

It has a great capacitor tester and some other bells and whistles.

I think I paid $125 for it.

[Phil_S]

Just in case there was a doubt in anyone's mind, I thought I'd follow up on the Amprobe that arrived in the mail today.

I believe I said, "It turns out that I'm a sucker for the bargain DMM." I am pleased to report that my self assessment (sucker) is on target and that expectations were met

It is a good thing this meter only cost $48.30 including s/h, because, IMO, it certainly isn't worth more than that. Remember, this thing supposedly retailed for around $99 plus s/h ($6.45 USPS priority).

The bad:
Looks cheap.
Runs on a pair of AAA batteries.
The extra cheap included batteries were DOA.
No backlight.
Don't like the feel of the rotary swtich.
Cheap test leads.
There was oil in the battery compartment. <weird, battery leakage?>

The good:
Pretty good value for for what I got.
Large display.
In addition to the basics, it does caps, diodes and continuity beep.
Auto range gives a stable reading quickly.
Appears to be calibrated well from the factory.
Fairly light weight.
Nice rubberized casing.
Auto sleep mode 30 minutes.

Overall, not a bad meter. By contrast, the Triplett really felt and behaved like a high quality item. At the $100 price point, this Amprobe would be a clear loser. I know, for $90 I could have had the Triiplett and for a little over $100, I might have scored a used Fluke on eBait. Oh well. Like I said, expectations were low and they were met. This meter will do the job for me and I've always got the Fluke 8600A bench meter, too.

[selloutrr]

Congratulations?

make sure the cheap test leads are suitable for the voltage you are working with.

The AAA scare me I'd keep an eye on it for a bit and make sure the calibration doesn't shift with battery life. esp when testing diodes and caps and such.

[Cygnus X1]

Call me backwards.
I have an A.W. Sperry DM-8A I prayed would die someday so I could buy a Fluke.

17 years and still going strong!

I have a nice auto-ranging Fluke at work but I feel much more comfortable with the Sperry due to familiarity (I guess).
Still find my old Sears and Rat Shack analogs handy for observing needle movements on caps.