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Ground Loop Isolator - Aux In for CDR-220 Radio

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I have a 2000 Boxster with a CDR-220 radio. I installed an auxiliary input for use with an iPod using the standard adapter from Becker, and a Belkin adapter as shown in this thread: http://www.renntech.org/forums/index.php?showtopic=5190

I used the same set up for my friend's 2002. Last week my friend told me he was hearing a hum on some of his music. (He listens to a variety of music including classical that contains quiet passages.) I thought a ground loop isolator would solve the problem. Even though I don't normally listen to "quiet passages" I thought I might as well put an isolator in both cars.

I installed the ground loop isolator in my car last night. It caused the stereo to act strangely. It played normally for about 2 minutes. Then it turned itself off and showed the word "PHONE" on the display. I tried resetting everything by disconnecting the battery. That fixed it for 2 minutes and then it went into "PHONE" mode again.

I don't know whether I got a defective unit, or if it is just incompatible with the Porsche radio. I removed it and returned it to Radio Shack.

Does anyone have an idea what caused this? Should I buy a different ground loop isolator? I've had good luck with components I've bought from David Navone and I thought I might try his.

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I have a CDR220 in my '99 and also 'tried' to use a R/S GLI. Needless to say, it did not work at all. So I too returned it and bought one at Best Buy. Seems to work fine. I guess if you didn't need it in the first place, I would run w/out it. Otherwise, try Best Buys as it also has an external ground you can use. Good luck!

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since the ground loop isolator is just a passive pass-through there should be no differences with it plugged in or not

if your radio is saying PHONE I'm guessing you cut into the phone power cable and need to check that wiring, a short there could make your radio think the phones is on, or worse yet cause a fire

(I know that the isolator and the phone power aren't physically connected, but given how tight it is down there I've got to beleive you bumped or tugged the power tap)

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I agree with stumpjumper, it sounds like the mute line on the harness is shorting. On other comment though, I read recently that a good alternative to the ground loop isolator is to power the device from the +12V instead of the ignition, it is a much cleaner signal. If you want to power it automatically you can use the IGN connector and a relay to switch the power on and off.

Good luck!

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