Hot Rod Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
57 Posts
Discussion Starter #1
Hey all. I just was given (Christmas present) a Sears DVOM by my MIL. Couple questions- The numbers in my manual for coil are, secondary 7200-9500 primary 1.28-1.42 The test (with my new meter :)) shows secondary 9600, primary 1.8. Are these numbers with-in range? On the condensor test I set MM on OHMS in auto range. The mm rises slowly up to about-well, sometimes it goes to 31point something and then it will hold there and maybe drop to OL or it might not. Another test will have it rising (again, slowly) up into the 4 digits- maybe, once again, it may or may not drop back to OL. Since I am new with all this, what am I seeing here? To my understanding the numbers on the condensor test should rise to infinity (What would this look like on the DVOM?) and back to zero "real" fast! In other words what numbers should I see? I sure i will have more questions on this new (to me) DVOM but I will stop with thoseLOL! I am certaintly open for any tips/pointers from you folks in terms of operating this MM. Again. I have never even used one of these new-fangled gizmos :spank: . I hope this has been coherantLOL. Thanks for any help as it is much appreciated!

Keith
 

·
Registered
Joined
·
7,345 Posts
Doc here, :pimp:

Standard Readings on a Remote (Non HEI GM type Coil) will be :

OHMS SET to RX1, CALIBRATED to 000, Primary Side of coil, LESS than an ohm, but more than 000.

OHMS SET to RX10K or higher, SECONDARY SIDE of the coil, 10,000 to 11,000 Ohms.

On a GM HEI type, The primary is the same as above..

The Secondary needs to be set to auto range, and should read between 6,000 and 30,000 ohms.

On a Cap, It should start out as a high Ohm reading and slowly taper off to 000 or Infinite, then reverse the probes and it should do the same again. If it drops quick, or hunts around get a new one..they are only a few bucks!

Doc :pimp:
 

·
Registered
Joined
·
806 Posts
If you want good advice using your DVOM I suggest reading doc's post at the top of this forum called "How does this stuff work" its a pretty good read.
 

·
Registered
Joined
·
57 Posts
Discussion Starter #4
oldschoolrods said:
If you want good advice using your DVOM I suggest reading doc's post at the top of this forum called "How does this stuff work" its a pretty good read.
Somebody (no name) said- If you want good advice using your DVOM I suggest reading doc's post at the top of this forum called "How does this stuff work" its a pretty good read.

In Docs words- "I think what we have here is a failure to communicate..."LOL I appreciate your(whatever your name is) "most sound" advise but I have "indeed" read (more than once) Doc's post on the dvom and while It gives great advice on "how to operate" a DVOM, it does not answer my question. My question was not "how" to operate a dvom (since I provided numbers/readings), but rather, "how" to interpret the readings. since my readings ( as stated in my initial post) are slightly out of range, my question simply was /is- could this mean my coil is suspect/weak? Again, my manual says my primary should be 1.28-1.42. the meter reads 1.8. Is this within acceptable range for the primary side? The manual then states for the secondary side it should be 7200-9500. The meter reads 9800. Are these acceptable numbers for the secondary? Again, I'm not asking "how" to get the numbers, but rather, how to understand the numbers I am getting. So, once again, the question is- are the numbers i am getting (compared with the numbers in the manual)within range, or are they indicative of a borderline/weak/bad coil? Anyone? Thanks.

Keith
 

·
Registered
Joined
·
806 Posts
I am certaintly open for any tips/pointers from you folks in terms of operating this MM. Again. I have never even used one of these new-fangled gizmos


that was in your origonal post, I do not know wether your coil readings are good or not, I was simply trying to offer you some tips, apologzie if I offended you for not having my crystal ball to know what you have and have not read.
 

·
Registered
Joined
·
7,345 Posts
docvette said:
Doc here, :pimp:

Standard Readings on a Remote (Non HEI GM type Coil) will be :

OHMS SET to RX1, CALIBRATED to 000, Primary Side of coil,****----> LESS than an ohm, but more than 000.<----****

OHMS SET to RX10K or higher, SECONDARY SIDE of the coil, ****------->10,000 to 11,000 Ohms.<-------****

On a GM HEI type, The primary is the same as above..

The Secondary needs to be set to auto range, and should ****----->read between 6,000 and 30,000 ohms.<--------****

On a Cap, It should start out as a high Ohm reading and slowly taper off to 000 or Infinite, then reverse the probes and it should do the same again. If it drops quick, or hunts around get a new one..they are only a few bucks!

Doc :pimp:
Doc here, :pimp:

The ABOVE IS the standard readings for MOST stock coils..For MOST American Cars..If yours differs, and is higher / Lower...It's weak or bad..We Must go on that basis, Since you DID NOT provide the Car or IGNITION system.

If you have something OTHER than stock..you MUST meet those standards.

ALSO, Bare in mind, an Ohms check will not detect Internal Arc over at all..You need an Oscilloscope with a proper time base to detect that..SO if you suspect it, Replace it.

Doc :pimp:
 

·
Registered
Joined
·
57 Posts
Discussion Starter #7
are these numbers good

oldschoolrods said:
I am certaintly open for any tips/pointers from you folks in terms of operating this MM. Again. I have never even used one of these new-fangled gizmos


that was in your origonal post, I do not know wether your coil readings are good or not, I was simply trying to offer you some tips, apologzie if Ioffended you for not having my crystal ball to know what you have and have not read.
Hello. No problem young man. I should have been More concise (conversing in print is HARD for meLOL). I should have said that i have never used one in the past but am pretty/kindalol comfortable now ( with the help of Doc, and this site). I figured that by posting the numbers from the DVOM, it would be assumed that I knew "how" to check the coil but that i was asking if, in this particular application if the numbers were to far out of spec. I should have made it a generic question like this- if a particular coil (irrespective of car make) is rated for 7200-9500 in the secondary, how far above or below (percentage wise) these specs would a coil have to be before it began to weaken. I have not seen this addressed in the literature. I APOLOGIZE to you as i thought you were trivializing my question and I see that was not the case :embarrass! As Doc. stated- "failure to communicate." Now on to my issues. I plan on getting a new coil and the works soon, and now (with the help of this BB) that I am comfortable "using" the DVOM, I would just like to "comprehend" these numbers better. On another note, it is good to see a young man hanging around a bunch of great folks as those on this BB! Later :thumbup: Later

Keith
 

·
Registered
Joined
·
7,345 Posts
Doc here, :pimp:

What is most significant is the Primary Numbers..(although Secondary Numbers have an effect also) The Primary Needs a "Jolt" to Induce cutting lines of force Across the magnetic core of the coil..

If you apply Ohms law:

I=E/R:

12 volts / .3 ohms = 40 amps...as opposed to:

12 Volts / .8 Ohms = 15 amps..

you can see the primary is pulling 40 amps (a lot of punch ) as opposed to the Primary on the second example, 15 amps, a lot less working power.

Second only to that, many guys will spend hundreds of bucks installing "Super Wiz Bang " Ignition systems , and under gauge the wire with a 12 or 14 gauge wire (which would be good for stock) and end up with current swamp in the wire being used up as heat...Not doing any useful work..(and adding to the resistive value).

And then they wonder why it doesn't run any better than before..That wire should be 10 gauge.

Doc :pimp:
 

·
Registered
Joined
·
806 Posts
Hey no problem keith :thumbup: Now that your comfortable with your meter you'll wonder how you ever got along without one, I've done quite a bit of DVOM work in school and I wonder how I ever tried troubleshooting without one :thumbup:
 

·
Registered
Joined
·
7,345 Posts
oldschoolrods said:
Hey no problem keith :thumbup: Now that your comfortable with your meter you'll wonder how you ever got along without one, I've done quite a bit of DVOM work in school and I wonder how I ever tried troubleshooting without one :thumbup:
Doc here, :pimp:

Wait until you learn to use an Oscilloscope or Spectrum analyzer!

You will be able to "See" signals you could never measure before, in a graph.

Doc :pimp:
 
1 - 10 of 10 Posts
Top