I have a Frontman 212R in for no sound. Customer had attempted to remove chassis from cabinet and got it stuck. I got it out and determined the chassis was working, but that both speakers were open. I was surprised, but the customer OK'd Eminence replacements. I ordered a pair and then pulled the bad ones out. While they were out, one definitely is open, but somehow the other one measured good. I checked the wires and connectors, everything looks good. This is when I discovered something strange.
While measuring the one I thought was good, the readings would go all over the place from 7.2 to open for a time. I thought it must be my probe contacts, but it did it whether connected to the terminals, the speaker leads from the push on connectors, or the braid itself. I can make the static impedence reading change by exercising the cone a few times. It sat at 7.2 ohms for a while, causing me to make a dash to the phone to cancel one of the new speakers I had just ordered. But, then I find I can make it go from anywhere from 7.2 ohms to a few hundred 0ccasionally for a few seconds, and watch it drop down to 25 or so. Mostly it just stays between 9 and 16 ohms.
Now, I realize I will see change while the ohmeter is connected and the cone is flexed. It is in the following several seconds after it stops that I get these random readings. It has been sitting at 13 ohms for a minute now. I just flexed it and now it is at 9.3 ohms. Did it again and now it is 11.2 ohms. Also, I can make it change by rapping on the frame with a screwdriver. Another flex, and back down to 7.2 ohms.
What is causing this? I am hearing no coil rub.
While measuring the one I thought was good, the readings would go all over the place from 7.2 to open for a time. I thought it must be my probe contacts, but it did it whether connected to the terminals, the speaker leads from the push on connectors, or the braid itself. I can make the static impedence reading change by exercising the cone a few times. It sat at 7.2 ohms for a while, causing me to make a dash to the phone to cancel one of the new speakers I had just ordered. But, then I find I can make it go from anywhere from 7.2 ohms to a few hundred 0ccasionally for a few seconds, and watch it drop down to 25 or so. Mostly it just stays between 9 and 16 ohms.
Now, I realize I will see change while the ohmeter is connected and the cone is flexed. It is in the following several seconds after it stops that I get these random readings. It has been sitting at 13 ohms for a minute now. I just flexed it and now it is at 9.3 ohms. Did it again and now it is 11.2 ohms. Also, I can make it change by rapping on the frame with a screwdriver. Another flex, and back down to 7.2 ohms.
What is causing this? I am hearing no coil rub.
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