NAD 1600 Severe Problems... Help!

[Turnor Brown]

I have a NAD 1600 (with remote) that I bought for $100. Unfortunately, I did not test to make sure it had output before I bought it. All of the lights came on, so I assumed it worked.

As of now, the only source of output from this preamp is through the EPL output. There is absolutely no audio coming form the preamp output jack or the headphone jack. The audio coming from the EPL output is very distorted.

I can select any source on the preamp and hear the single audio source I have hooked up to the preamp. Even with the tuner on, I can still hear the audio source. Usually the audio output is least distorted when the proper input is selected. The volume knob can occasionally change the level of distortion heard through the EPL out.

I read that the glue used on components in this preamp can become conductive over time, so I removed as much of it as I could. I also read that the main relay in NAD equipment sometimes goes bad, but mine tested to be functioning normally. I sprayed deoxit in all moving components of the preamp as well. None of these potential solutions have helped my situation.

One other thing I noticed was that even with the preamp switched off, the switched power output on the back of the preamp still had voltage going to it. Turning on the preamp would raise this voltage to equal the line voltage.

I know just enough about electronics to do basic troubleshooting. I'm comfortable with a soldering iron, so working on this preamp should be no big deal. However, I am at a complete loss for solutions at the moment. I watched a video of a repairman working on a preamp with similar issues to mine, however he was successful in fixing his NAD! I'm beginning to become worried that this is a non-repairable issue with the IC's.

I would prefer to fix this preamp myself mainly because there are no repair shops locally. Plus, I enjoy fixing things like this.

Any help would be appreciated.

 

[The Fuxtor]

I would look closer at cold solder joints..... try reflowing any suspect looking areas

 

[Turnor Brown]

I reflowed the worst looking solder joints, and I tested continuity between them as well. Still no luck.

 

[avionic]

And audio signal generator and an O'scope would certainly be handy.

 

[ryuuoh]

Might be worth your time to watch:

 

[Frabor]

did that to mine + a board clean-up with alcohol (nicotine and dust) + dioxit of all the pots, came out good. i was able to fix a channel imbalance.

 

[Frabor]

one year later, mine is working great. The cleanup was a huge difference. I just took it from out of rotation and I installed power supply capacitors as they were bad, replace the caps of the 7805 and 7815, deox the motor pot and reflow the joints of the volume pot. It is working great, planning to do more updates, starting with the regulator and the diode bridge and the caps on them.

 

[Frabor]

I changed the input caps of the 5V and 12V lines ( radio board), both 78xx regulators. The caps were burned, due in part that the 5V (7805) is an always on device to power the logic. Now it is connected via an external wifi relay, so it is not connected to mains while off. Increased the capacitance a little, using 2200uf, that I had available

I have a NAD 1600 (with remote) that I bought for $100. Unfortunately, I did not test to make sure it had output before I bought it. All of the lights came on, so I assumed it worked.

As of now, the only source of output from this preamp is through the EPL output. There is absolutely no audio coming form the preamp output jack or the headphone jack. The audio coming from the EPL output is very distorted.

I can select any source on the preamp and hear the single audio source I have hooked up to the preamp. Even with the tuner on, I can still hear the audio source. Usually the audio output is least distorted when the proper input is selected. The volume knob can occasionally change the level of distortion heard through the EPL out.

I read that the glue used on components in this preamp can become conductive over time, so I removed as much of it as I could. I also read that the main relay in NAD equipment sometimes goes bad, but mine tested to be functioning normally. I sprayed deoxit in all moving components of the preamp as well. None of these potential solutions have helped my situation.

One other thing I noticed was that even with the preamp switched off, the switched power output on the back of the preamp still had voltage going to it. Turning on the preamp would raise this voltage to equal the line voltage.

I know just enough about electronics to do basic troubleshooting. I'm comfortable with a soldering iron, so working on this preamp should be no big deal. However, I am at a complete loss for solutions at the moment. I watched a video of a repairman working on a preamp with similar issues to mine, however he was successful in fixing his NAD! I'm beginning to become worried that this is a non-repairable issue with the IC's.

I would prefer to fix this preamp myself mainly because there are no repair shops locally. Plus, I enjoy fixing things like this.

Any help would be appreciated.

While maintaining mine, I Learned that the 5V line, at least in the 1700, is always on. It is used for the logic circuitry. I believe the 12V line is always on also.
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