How to check an IC?


Hi,
I just made some ICs, and want to make sure there are no shorts, etc.
Can somebody guide me through this?
What I did is turned my R-Shack voltmeter to Ohm x1. and connected probes to the RCA barrel on both ends, and then to both central pins- meter showed about 400 Ohms? in both cases.
Does that mean the IC is OK?
I'm completely illiterate, when it comes to DIY, etc.
maril555
400 ohms is high...theoretically it should be zero...in reality, probably fluctuate around zero. The procedure is as follows...

1) Make very sure you ohmeter/voltmeter is set to measure resistance...check this by touching the probes together...you should get about zero...and (depending on meter) a beep for continuity. (Make sure to use Ohms rather than Kohms if you have the choice...because Kohms may round to zero)

2) Then put one probe on the barrel on one end...and the other on the other end...you should get about zero

3) While keeping one probe on a barrel, put the other on the pin of the other side...you should get "open" or infinite resistance...

repeat with all permutations/cables.

400 is too high...but is your meter working right?
Simply check for continuity-pin to pin then ground to ground, then check pin to ground to make sure there are no shorts. What this does is establish everything is connected correctly. On my rat-shack meter there is a setting for continuity. If you hear a steady tone you have a connection. The previous poster is correct about the ohms, as it should be 0 or very close to zero.

I use a cable tester to check my work. Plug them in, turn the device on & presto! Same goes for AC cords.
When I turn multimeter to Rx 1, and touch probs together- mit shows 300 ohm, when I check a cable (not my DIY cable, but one, I know is fine - I get exact same reading.
BTW, the Ohm scale reads from left to right (it's analog RS multimeter)from infinity to zero
What I meant is, an arrow moves just a little bit from infinity to the right, towards zero.
When i probe is on the barrel and the other on central pin on the other end it doesn't move- "infinite resistance', just like MI8764ag said.
If you're on the 1 ohm scale the 400 almost certainly means 400 military ohms, aka .4 ohms.
No worries there if it reads 300 milii ohms with the leads shorted (means your cable is adding only 100 mili = .1 ohms).
You should see low ohm readings from outside ground to outside ground.
You should be OPEN from center pin to outside ground connector.
My spell checker apparently inserted military when I typed mili as in mili ohms.
If you're on the 1 ohm scale the 400 almost certainly means 400 military ohms, aka .4 ohms.
No worries there if it reads 300 milii ohms with the leads shorted (means your cable is adding only 100 mili = .1 ohms).
You should see low ohm readings from outside ground to outside ground.
You should be OPEN from center pin to outside ground connector.
Sebrof,
Thanks.
Actually, the R x 1 scale on a Radio Shack analog multimeter is undoubtedly not a 1 ohm scale. It simply means that the number indicated on the dial scale by the pointer should be multiplied by 1, as opposed to being multiplied by 10 if the R x 10 scale were selected, or by 100 if the R x 100 scale were selected, etc.

There should be a small knob somewhere on the multimeter, labelled as "ohms adjust," or something similar. While touching the two probes together, turn that knob until the meter reads 0 ohms. If you can do that, then make your measurements on the cable. If you can't do that for any setting of the knob, it means that the battery in the meter is weak and should be replaced.

After performing that calibration, so that you have a reading of 0 ohms on the R x 1 scale when the probes are touching each other, as was indicated above the cable should measure either 0 or a tiny fraction of an ohm from center pin to center pin, and from ground sleeve to ground sleeve, and it should measure as an open circuit (infinity ohms) from center pin to ground sleeve.

When checking for shorts (i.e., between the center pin and the ground sleeve), it is generally good practice to use a higher scale than R x 1, for instance, R x 1000, to make sure that you will see the small deflection that may result from a high-resistance path between the two points, that shouldn't be there. When you do that, make sure that your fingers are not touching the metal tips of the probes, or you may see a deflection of the meter due to the resistance of your skin.

Regards,
-- Al
Almarg,
You are the man- it was low battery, after changing it and adjusting "ohm adjust" knob, I got the following:
IC #1: appr. 0.5-1 ohm b/w ground- ground and the same b/w center pins.
Infinity b/w ground and pin.
IC #2: 0.5-1 ohm b/w grounds, but 3-4 ohm b/w center pins
Infinity b/w ground and pin.
Does it look, like there is a problem with IC #2?
Yes, 3 to 4 ohms sounds too high, assuming that the length of the cable is not extremely long (for example, 50 feet!).

If you are confident that you did the measurement properly, and that before and after you made the measurement you checked that the meter read 0 with the probes touching each other, I would say that you have a marginal connection at one of the connectors.

Regards,
-- Al
Thanks, I'll try to re-do the RCA plugs. My soldering skills are in the developement stage yet.
BTW, what temperature on the soldering gun do you guys use for sodering RCA plugs?
I have Hakko 936 iron, and use WBT 4% silver solder.
When I used 700 F, as recommended by Chris Venhaus, I found it to be insufficient for this particaular job, and had to use my old RadioShack iron, which, I guess is hotter, and that did the job.
What size tip? I find 700 degrees and a fatter tip works very well for connectors.
I don't know what size it is, but it's small. Much smaller, than RS one.