I have a NAD 272 power amp linked to a NAD T752 A/V amp and have had ** end of problems. Purchased in 2005, 6 months after, the right speaker (Paradigms studio 60) channel would just fade away periodically, and then come back with a thump. Noone (NAD audio repair shop) could initially find any fault but when I powered just thru the 752, there was ** channel drop out.
The 272 was supposedly fixed, (altho NAD still say they could find ** fault)it happened twice again, and last fixed in November 2006. Last week, 6th March 2008, the same problem arose with the left channel. I have taken the CD player out of the equation, problem still existed, DVD player out of the equation, problem still there, the FM tuner in the 752, problem still there. Take the 272 out and put all speakers thru the 752, everything runs fine.
The speakers have been stripped down to ensure ** crossover wires are touching. I run a NAD CD, an OPPO DVD, a Project turntable thru a NAD preamp.
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Re: NAD 272 Channel drop out
Well..this is one for the books. Can you tell me what the ratings are between the 252 and the 752 impedance matching wise? even though it might work sometimes, impedance matching can wreak havoc between mismatched amps.
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It could be entering protect mode because it has no speakers wired to it, have you tried connecting to all 6 speaker - out connections. Often, if an amp can't detect a load on all 6 channels it won't work. Also, have you checked the thermal fuses? a blown fuse could cause this problem.
I hate to say this but the repair was not complete. If the sound levels are different with the balance in the middle, then either they missed a problem in one of the pre-amp stages, or they used an incorrect substitution for transistors in one or more stages. This unit should be brought back to complete the repair.
Any additional detail would require that I see the actual unit and poke around inside with test equipment.
I have had the front, left and right channels go out over time.I have fixed all of them, and each time it has turned out to be a cold solder joint.While I love NAD and will continue to purchase there equipment, this generation is plagued with poor workmanship.
To fix the channel going out, I removed the top cover.Back cover and 2nd card from the left (looking at the receiver from the back side).This card handles all of the audio processing.I have found cold solder joints all over this board which has caused channels to suddenly go quite.I have never found a bad component.Also, I have cleaned the interconnect to be backplane (board that the audio processing board connects to) in the case of the center channel going quite.
If you have poor FM reception, the first board from the left (looking at the receiver from the back side) may have a cold solder joint on the coaxial connection for the FM antenna.
The blue screen indicates a proper connection (signal received by the monitor). Try selecting "amp" on your HTR 2 remote then use any directional button at the center of the remote, the keys which circle the "Enter" button. Hopefully you will then see the menu appear. Use the same directional keys to navigate the menus.
i would go with the 801.And ithink u meant the 4501 not 4051.Both super power amps. competition stuff.your woofers are 4ohms dual voice coils.so you can series the coil on eaach woffer and use the two channels on the amp.they play at 2ohms.I think if you drop it down to 1 ohm you really be taxing you alternator that is series power.Yioou would need a special alternator.Even with them running in 2 ohms you better hav eat least a 2 farad cap.OR two batteries.. ! more thing don 't pump it up with window s closeed .you'll pop them.serious dbl. you be pumping.I'm jealous.Rating please and enjoy.
i would suspect a missing supply or speaker protect relay shorted? or staying closed too long. I'm not familiar with this model but a common failure is bad connections. Inspect all heat sinked parts and small value resisters used as fuses. Look for cracked solder joints on all parts, tighten pcb grounding screws. Memory is most likely powered by a high value cap or stack cap that maybe bad. Or the diode used to charge during usage maybe leaky , other part in ckt leaky, or the memory device itself is drawing excessive current off the memory cap. I have seen small 0.1uf disk caps turn into 1k resistors.
has bad 12 volt regultor and 2 5.1 volt zener diodes on the main board in the regulator circuit, also may have a few caps near these parts which also need replacing. ref # for the 12 volt reg is u703 , kinda a major job.
It sounds like You have a Bad output Some where and its going in to protect mode disconnect spkrs and make sure volume is Down all the way and power up,Ck your wireing for Freyed wires and shorts at the inputs and outputs
good Luck ttech