How to hook the 3490 to get 4 ohms - Harman Kardon Audio Players & Recorders

Most mono amps now a days give you multiple terminals. The older amps were a pain trying to stuff all the wires in one set of terminals. If the amp is rated at 2 ohms mono then make sure what ever configuration of speakers your running does not go below 2 ohms using both terminals. For example do not hook a 2 ohm load to each terminal. 2 ohms period between the 2 sets of terminals.

This amplifier can go into protection if one of the low ohm resistors on the power module that is soldered to the transformer is defect. Check out R951 and R952, they are both 0R47 (0,47ohm). They are often broken and measure some kilo ohms.

You can try a factory reset after checking your speaker wires for shorts. The procedure is in your owner's manual. This will most likely not resolve your issue. If you need further assistance, or would like to inquire about repairing your Harman Kardon, please visit my website at audioserviceclinic.com and contact me there. BTW, I worked for Harman, as Technical Support for all Harman, JBL and Infinity products.Thank you.

maybe it can help you http://www.comco-inc.com/ibm-3490-f00-p29908.html

AMPLIFIER HARMAN KARDON:
Code: <check input> means: fuses resistors back of the transformer. They should have .4 ohm low ohm. Often they go on kilo ohms or mega ohms, means they are open. Change them. That's it. Code: <Check DSP> means something on logical board or flat strap connectors defect. Also check voltage on output collector and also check -15 volts and +15 volts on multiplug up on the middle right of the amp on the logical board. Check all voltage preamp on connector cn21 and cn24 on right of the logical board up middle right of the amplifier. I'm a certified Harman kardon technician. If you have other questions, just ask me. Good luck all. Serge.

Ok, your post has two different models listed. Let's start with something you need to know about your amplifier. Is it one ohm or two ohm stable. This will make a difference. Also, whether your subs are single voicecoil (HFI12s4) or dual voice coil (HDI12d4).

Let's start with the easy scenario. Let's say your amp is two ohm stable and you have two single voice coil subs. It's simple. You go from the positive of the amp to the positive of both subs and the negative of the amp to the negative of both subs. This will provide a 2 ohm load to the amplifier, thus pulling all the power out of it.

Unfortunatley, if you have two dual voice coil subs, you won't be as efficient. You will only have the options of a 4 ohm load or a 1 ohm load.

This is where having a one ohm stable amp would come in handy. If the amp is one ohm stable, hook the positive of the amp to all 4 of the positives on the subs, and hook the negative of the amp to all 4 negatives of the subs. This produces a 1 ohm load.

WARNING!! If you have a 2 ohm stable amp DO NOT use the last wiring scenario. It will fry your amp.

Now, the last is a little trickier. This is for two dual 4 ohm subs. Follow closely. Hook the positive of the amp to one of the positives of each sub. (do the next step to both subs) Go from the negative of the voice coil that you hooked positive from the amp is hooked to, and hook that to the positive of the unused voice coil. Then go from the negative of that voice coil and hook to the negative of the amp. Make sure this is done on both subs. This will give you a 4 ohm load.

Hope this helps

your speakers are of an incorrect ohmage, or you have too many speakers hooked up to it. your stereo likely calls fo a singler 4 ohm (4?) speaker per channel and the factory speakers may be lower than 4 ohms, or you have several speakers hooked up to the same channel. there should be 4 channels, each with no less than a 4 ohm (4? ) load. two 4 ohm speakers wired to the same channel in parallel (both attached to the amp's poositive/negative leads) will create a 2 ohm (2?) load, and overheat the amp. if the 2 speakers are a woofer/tweeter combination, and there is a capacitor involved, it may be ok, but 2 woofers, or a woofer and a subwoofer hooked to the same channel will likely reduce the ohmage below 4 ohms (4?). look at the back of each woofer speaker, and look for an ohmage rating stamped to the back of the speaker magnet to verify that they are 4 ohm (4?) speakers, and verify that only a single 4 ohm speaker is hooked to each channel. the car likely has multiple speakers hooled up to each channel, which would lower the ohmage rating below 4 ohms (4?).

Yes, Your camera cover is covered under the same warranty as your camera, so remember your serial number when calling:
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first you dont bridge both ,, 2nd you will need to find out what ohms your speakers are , and if dual coil what ohms each coil is ,, then find out what ohms your amp runs at , at full power.. then try to match your subs to the same ohm load,, REMEMBER there are diff ways onto how to hook subs on which will change the ohms.. good example 1 dual coil sub each coil is 2 ohms then you can hit a 1 ohm or 4,, depending how you hook them up .. When adding more subs and how you hook them up changes the whole game.. if your not sure on how to hook them up read a manual or go to a local shop you can burn your subs up or worst the amp if hooked up incorrectly ..

You should have no problem with 8 ohm speaker with this unit as you would with the 6 ohm speakers. The 6 ohm requirement is only not to go under that value. The only consequence of hooking up higher impedance speakers(8 ohm) to this system is that you will have slightly lower volume than with lower impedance speakers(6 ohm).