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HokieAg07
08-02-2008, 01:49 AM
Well I have an issue on a 2 wire system with a MDC-100 and I need to purchase a ampermeter or multimeter with clamp to measure amp draw so I can pinpoint the issue. I need something that goes as low as 0.5 mA. I just want to see what you guys are running or recommend. I am prepared to spend money on something nice like a Fluke or equal.

FIMCO-MEISTER
08-02-2008, 08:29 AM
Somebody please answer this I'm curious. I'm looking for a new multimeter myself. I'd like a recommendation. Needs to have big digital letters or numbers on the display is my only request.

Wet_Boots
08-02-2008, 08:47 AM
I bought a three-dollar multimeter from Harbor Freight - thing actually works.

Waterit
08-02-2008, 09:36 AM
Needs to have big digital letters or numbers on the display is my only request.

I bought one with a clamp at Radio Shack last year that had a nice readable display without glasses (another sign of getting old, um, more experienced:laugh:).

Don't remember model # and unfortunately meter didn't survive falling off toolbox and onto roadway when some idiot forgot to put it away.

Wet_Boots
08-02-2008, 09:47 AM
I think Harbor Freight also has a cheapie clamp-around. Absent a meter that can read AC current, one can always connect the load current through a precision resistor of low value that won't interfere with anything - then you read the voltage across the added resistor, and calculate the current from the voltage divided by the resistance.

irrig8r
08-02-2008, 10:20 AM
I have two. The Commercial Electric brand multi meter with amp clamp I bought at HD a few years back works fine for my irrigation needs. Cost me maybe $40 tops.

My other one that I guard more carefully is a Greenlee True RMS multimeter that cost me more like $130.


http://www.toolup.com/Greenlee/CM-850.html

Wet_Boots
08-02-2008, 10:31 AM
The OP isn't going to get any sub-milliamp readings from a clamparound, though. If it's AC current, that's more expensive to measure than DC current, unless you employ the resistor trick.

CAPT Stream Rotar
08-02-2008, 02:48 PM
I heard craftsmen has a great one for 40 bucks.....


amp readings with the clips..

Mike Leary
08-02-2008, 02:55 PM
I'm pretty sure you've got to have a no b.s. meter to troubleshoot 2-wire;
I'd buy the baddest Fluke I could get my wet hands on.

Wet_Boots
08-02-2008, 03:23 PM
Fluke rules, but I love my clanky old Triplett 630 and Simpson 269

Mike Leary
08-02-2008, 03:25 PM
Fluke rules, but I love my clanky old Triplett 630 and Simpson 269

We used to use the Simpson in the studios, very accurate.

Wet_Boots
08-02-2008, 03:28 PM
I started with a Lafayette Radio VOM, which probably still works, except for maybe frying the high-current-range resistor.

Mike Leary
08-02-2008, 03:34 PM
frying the high-current-range

That was pretty common in the sixties.:rolleyes:

CAPT Stream Rotar
08-02-2008, 04:03 PM
how much are flukes running now boys?

What makes it better than the rest?

HokieAg07
08-02-2008, 04:15 PM
I'm pretty sure you've got to have a no b.s. meter to troubleshoot 2-wire;
I'd buy the baddest Fluke I could get my wet hands on.

Thats what Ive been told, now I just have to figure out which model to get... Money isnt really an option, I have to have this to troubleshoot 2wire and they are getting more and more common..

Wet_Boots
08-02-2008, 04:28 PM
Thats what Ive been told, now I just have to figure out which model to get... Money isnt really an option, I have to have this to troubleshoot 2wire and they are getting more and more common..Is this all AC current you're dealing with?

HokieAg07
08-02-2008, 04:34 PM
Is this all AC current you're dealing with?

Yep sure is

Wet_Boots
08-02-2008, 04:41 PM
AC current puts you into the premium seats. Start with a base-model Fluke, and work from there.

Mike Leary
08-02-2008, 04:45 PM
I researched two-wire years ago for various large systems (the only ones that make sense for two-wire), and came to the conclusion that trouble-shooting would be the biggest drawback. Tucor spec'd meters for dealing with problems, I have enough problems with 24 volts.
Given the extreme sensitivity of two-wire systems, would I design one, I'd spec conduit.

Wet_Boots
08-02-2008, 05:00 PM
Yeah, start with mfr recommendations and work from there.

Mike Leary
08-02-2008, 05:20 PM
Yeah, start with mfr recommendations and work from there.

Duh.........I'm afraid the pups will not even read the specs.

HokieAg07
08-02-2008, 09:19 PM
Ill do some checking with Rainbird and see what they recommend

Wet_Boots
08-02-2008, 09:23 PM
Low AC current like you describe is a toughie. There is a HVAC model with a microamps range, but I don't think it has higher AC current ranges.

HokieAg07
08-02-2008, 10:07 PM
Okay Rainbird says from 2mA-20A is the range I need

bicmudpuppy
08-02-2008, 10:16 PM
http://www.sears.com/shc/s/p_10153_12605_03482369000P

I bought this one a few weeks ago and, for the price have been very impressed. We've used it for everything from troubleshooting golf carts to pumps. (bought it because the overload on the sustain pump went bad)

Wet_Boots
08-02-2008, 10:42 PM
Okay Rainbird says from 2mA-20A is the range I need20 amps? Seems a bit much for 2-wire.

HokieAg07
08-02-2008, 10:47 PM
20 amps? Seems a bit much for 2-wire.

Yeah I agree, I think the main point though is the 2mA.

I was hoping to go out and buy one this weekend so I could troubleshoot first thing Monday as the whole system is down because of this short.

Well RB recommends the Kyoritsu 8112 Clamp Meter, but I cant find much info about it much less a place to purchase one local.

Mike Leary
08-02-2008, 10:53 PM
the whole system is down because of this short.

When two wire goes down, there is no spare wire, nada.:cry::cry:

HokieAg07
08-02-2008, 10:59 PM
When two wire goes down, there is no spare wire, nada.:cry::cry:

Of course this is at a HOA with 55 and older seniors who like to stay up all night to watch their irrigation come on. This place has some of the greenest turf in the area and they are constantly telling me the irrigation isnt working (of course as of the other day it isnt :laugh:) and that it needs to be completely redone. :dizzy::hammerhead:

txgrassguy
08-02-2008, 11:35 PM
When you guys mention a "two wire" system, are you referring to an encoder system?
I have trouble shooted several encoder systems with my trusty 521 after disconnecting the power source - lead me right to the problem and found the modules quite easily too.

jrumbaug
08-03-2008, 07:52 AM
I'm new to irrigation, but old to electronics and electricity.
Why is 2ma detection needed to troubleshoot a faulty circuit??
Most problems are open ( most common ) or shorted circuits.

Jim Rumbaugh

FIMCO-MEISTER
08-03-2008, 08:25 AM
I'm new to irrigation, but old to electronics and electricity.
Why is 2ma detection needed to troubleshoot a faulty circuit??
Most problems are open ( most common ) or shorted circuits.

Jim Rumbaugh

Welcome to the site Jim, hang around, we could use a fresh dose of common sense the way things have been around here lately, especially on electrical issues.

HokieAg07
08-03-2008, 09:48 PM
Damn these 2 wire systems...

Anyways I am still trying to figure out what I need. Some people are saying all I need is one that has a resolution down to 1 mA and others are saying I need a current leakage tester which has a range of 0 mA to 60A.

Mike Leary
08-03-2008, 09:54 PM
Damn these 2 wire systems...

Anyways I am still trying to figure out what I need. Some people are saying all I need is one that has a resolution down to 1 mA and others are saying I need a current leakage tester which has a range of 0 mA to 60A.

It depends on what your testing, but if you're going to run with the big dogs,
and it seems like two-wire is the next thing, you've got to have the meter
that tracks a fart in the night.

Wet_Boots
08-03-2008, 09:59 PM
It won't be a meter so much as a scope, like a graphing calculator is more than just numbers.

Mike Leary
08-03-2008, 10:34 PM
It won't be a meter so much as a scope, like a graphing calculator is more than just numbers.

That's what I've been told, too. I think Tucor makes their own unit.

bicmudpuppy
08-03-2008, 11:49 PM
Two wire fascinates me, but the Toro OSMAC Satellites I have will not openly support two wire. I haven't looked to see if I can combine systems within the computer, but I am fairly sure it would require a separate "base" station in my office to com with the upgraded satellite. What happened to the Underhill rep that was dropping in? Was her name Toni? (I assumed female from the conversations I had).

jrumbaug
08-04-2008, 07:29 AM
I not bashful about talking about things I know nothing about, but ......

I ASSUME ( and I know what happens when you assume ) a 2 wire system sends solenoid power via the 2 wires AND a logic signal of some type is over the same wires. The signal may be radio frequency or some other type pulsed voltage. Perhaps like DSL where Internet and phone co-exist.

SO ... What is trying to be measured? Back in my TV repairing days, a co-worker said."you can't fix what you can't measure"

And

what is the problem?

How I would begin. ( I ASSUME (I know, I know...) that all the valves are wired like a string of Christmas lights on a parallel, not series, circuit.

IF the WHOLE SYSTEM is down... try to get the first/closest valve working. You may want to disconnect the wires going to rest of the valves to ISOLATE THE PROBLEM.

1)Check for the main voltage at the closest valve to make sure you don't have a broken wire.
2)If you have voltage but cannot turn it on, expect that the transmitter (controller) is bad.
3) If no voltage, possible short (check with regular ohmmeter) or more likely, open circuit.

I hope this helps

Jim Rumbaugh

Kiril
08-04-2008, 08:49 AM
Well RB recommends the Kyoritsu 8112 Clamp Meter, but I cant find much info about it much less a place to purchase one local.

The 8112 is a clamp adaptor.

http://www.kew-ltd.co.jp/en/products/clamp_adaptor/8112.html

Grainger (http://www.grainger.com/Grainger/wwg/start.shtml) has a pretty nice selection of meters, but I don't see the Kyoritsu

HokieAg07
08-06-2008, 08:22 PM
Well I picked up an Extech clamp meter for 175 that went down to 1 mA. It is pretty nice it is a full featured DMM as well so I can use this for all my electrical troubleshooting.

I fixed the system today, troubleshooting this 2 wire stuff is easy once you understand the principles behind it and get out there and just take readings. You need to know as much as possible about the system before you go troubleshooting. Unforetunately the guy that did the install here is not known for his quality work. :dizzy: He does horrible jobs. I gave him a call and he actually called me back with some info, main thing being if it was a looped setup or not.

I tracked the entire wire path with my 521 a few days ago just to give me an idea of how it was laid out since I dont have any as-builts.

So I looked on my Rainbird software and got a general idea of how many 1,2, and 4 address decoders I had in the field and added up their current usage. Then I broke the loop and started working my way around. I started off with 250 mA which is 200 more than it should be. It was amazing how many valve boxes I opened to see no DBY/DBR splices, just bare wirenuts. I finally came to a valve box which and the current after one of the decoders dropped down to 6 mA. As I undid the splice the Maxi Cable fell apart in my hand. So I redid the splice and tried again, still had a high current reading so I took the decoder out of the picture and success.

It was amazing how bad this install was, I am going to have go around and check all splices and repair many many of them. Also not a hint of grounding on the $3700 controller or anything in the field.

Mike Leary
08-06-2008, 08:34 PM
[QUOTE=HokieAg07;245431 Unforetunately It was amazing how bad this install was, I am going to have go around and check all splices and repair many many of them.[/QUOTE]

You make the money, but you're sure pissed off is was not done right.