Strange VOM Issue

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RustyRatRod

I was born on a Monday. Not last Monday.
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So, I'm doing some wiring repairs on James' 63 Dart now. It had a pretty good meltdown behind the cluster. I have pretty much got it all repaired. Went to hook the battery up to test for power. My Fluke meter's battree is dead, so I broke out my Bosch VOM and started testing. I tested the main wire coming in and got 18.6V. So I immediately opened the hood on the Valiant and got 18.6V on her battery. Bullshit. So today I got a new 9V battery for the Fluke and I have 12.5V on Vixen and 12.4V on the 63 Dart. What can make the Bosch read like that? Is it possible to adjust it maybe?
 
Meters can lose calibration but not knowing what you are using it’s difficult to troubleshoot from here.
 
First thing I do with any DVOM when it starts acting funny is put a fresh battery in it. Well, except for the cheap Harbor Freight ones... they just go in the trash.

My Fluke says all kinds of strange **** when the battery gets low.
 
First thing I do with any DVOM when it starts acting funny is put a fresh battery in it. Well, except for the cheap Harbor Freight ones... they just go in the trash.

My Fluke says all kinds of strange **** when the battery gets low.
I did.
 
Thats a DVOM it uses diodes. 12.5 times .5 equals 6.25. 6.25 plus 12.5 equals 18.75. failed diode.
Then it was bad when new. It's the first time I've ever used it.
 
If it has a good battery there is not much else you can do except attempt to warranty it. If it makes you feel any worse, the newest Flukes seem to be made "over there" as well. I have 5 of the old rectangular "70" series I hope to hell they all hang in there till I'm gone LOLOL
 
That's why I still have a Simpson 260. Rugged, reliable, never have to wonder what the hell is going on.
 
The problem with the Simpson 260 is that most of them skipped all the way from 10V to 50V. They needed a 25V scale. I think some of the later models changed that

Yup Late model series 8 has a 25V scale. Earlier models did not, which makes them close to useless on a 12V system

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Series 7............no 25V scale

simpson_260-7m_01.jpg
 
I'm a bit biased since my deceased Father worked for John L Fluke company for years, but if you contact them politely, they'll probably repair or replace your DVM for no charge. Contact them, please.
 
I'm a bit biased since my deceased Father worked for John L Fluke company for years, but if you contact them politely, they'll probably repair or replace your DVM for no charge. Contact them, please.
The Fluke is fine. It's the Bosch that's frigged up.
 
It just goes to show you cannot believe everything you see.....
 
I discovered that analog VOMs are almost always low impedance. Tried reading an O2 sensor on my '73 RR and it kept reading 0 volts. Tried using a digital VOM and got the correct output voltage. I have an old analog sweep VOM I haven't used in years. Kept it around for testing TPS sensors.
 
IMO,

You absolutely need both styles. I personally use a vintage analog Triplett 310 and digital Fluke 75 as my favorites.

Each has there own merits and benefits, in not only the automotive world as well as any low voltage world.
 
I discovered that analog VOMs are almost always low impedance. Tried reading an O2 sensor on my '73 RR and it kept reading 0 volts. Tried using a digital VOM and got the correct output voltage. I have an old analog sweep VOM I haven't used in years. Kept it around for testing TPS sensors.
There is a wide WIDE difference in non electronic VOM/ multimeters. I'm talking about the "traditional kind" that are not a VTVM (vacuum tube voltmeter) or a newer FET meter (transistorized meter with analog scale)

Look for the "ohms per volt". Back WAY back most old meters that first came out in the 30's--40's were only 1000 ohms per volt. These used a 1ma (1 milli amp) full scale meter. Some more modern meters by the late 50's --60's used 200ua (200 micro amp) meters and were 200,000 ohms per volt. Even those still "loaded" delicate circuits and were of no use in some circuits
 
I don't know how the analog discussion came about. I don't have one and that's not what I'm talkin about. I may try to find a decent one though.
 
IMO,

You absolutely need both styles. I personally use a vintage analog Triplett 310 and digital Fluke 75 as my favorites.

Each has there own merits and benefits, in not only the automotive world as well as any low voltage world.

Absolutely correct.
 
I don't know how the analog discussion came about. I don't have one and that's not what I'm talkin about. I may try to find a decent one though.

I think the 'analog' discussion is valid simply because of what 1969383S said. If you look at some procedures in the FSM, it will caution against using a digital meter. The high front end impedance of a digital meter doesn't load the circuit up enough to prevent false readings. If someone doubts this I can start going through FSM's but trust me, it's in there.
 
"False readings" That is certainly an issue especially with AC. I got into a knock down--drag out fight with the cable (internet only) company after a modem evidently died. the "technician" came out, got on the pole and claimed "I was feeding power back."

I told him the ONLY thing hooked to that cable is the company modem "which you guys" connected to it. Turns out he had the cable--which went from the house to the garage, at the company "box," with an arrestor and ground at that point, up through the garage, and out over the alley from a pipe pole He had the entire length of cable "floating" disconnected and had stuck his meter on it. OF COURSE it showed voltage--it was acting like an antenna, and your body can do the same
 
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