A novice question about a problem with Marantz 1060

[Keith Baran]

I have a 1060 that I “refreshed” about 1 year ago. Replaced all electrolytics, transistors ETC. Works great. The other day I picked up a pair of Marantz MA700 for free. I put them on my bench, hook up a pair of junk speakers, and a computer to play some music through to make sure nothing was wrong. They worked fine, clean sound, lot of volume.

So I take them into my living room and use the “Pre out” on my Marantz 1060 to the input of the amps. Turn on the power to the CD player, 1060, and finally the amps. I turn the gain up on the left amp to about half way. As soon as I begin to turn the gain up on the right side, Pop!

I put the 1060 back to normal with its jumpers in place (the state before I started all this) and the right side is all distorted and quiet.

My thought was the amp should be fine because I was using the “pre out” on the 1060 and the “amp in” had nothing plugged into it.

I put it on my bench and hook a mp3 player up to the amp in just to verify the amp portion is ok, but it is not, distortion out of the right side.

Can someone explain how I damaged the amp section, also what may be wrong? I don’t see anything blown, I haven’t begun to troubleshoot.

Any assistance would be greatly appreciated

Regards

Keith

 

[captouch]

Can you test the right MA700 to make sure it's still okay?

What I'm wondering is whether the right channel of the preamp portion of your 1060 is sending a bad signal whatever amp that's connected to it. So if your preamp right is bad, when you hooked it up to the pair of MA700's, maybe it damaged the right MA700.

At that point, maybe the amp portion of your 1060 was actually still okay. But then when you replaced the jumpers and turned on the 1060 to try it as a standalone, the preamp right channel again sent a bad signal to the amp portion of the 1060 and thereby damaging it.

If that theory were true, then your right MA700 may also be damaged. Even if it's not, it doesn't mean the preamp out is okay, because the MA700 may just be more robust and didn't get permanently damaged.

Ideally, you'd be able to connect a signal generator into one of the 1060 inputs and use an oscilloscope to look at the preamp outputs. But if you don't have that gear, maybe you use your MP3 player and download a sine wave signal. Then play that into one of your 1060 inputs and use a simple multimeter in AC voltage mode to just look for measured voltage differences between the left channel and right channel.

Because aside from your 1060 preamp right channel being bad, I don't see how you would have damaged your 1060 amp right channel when it wasn't hooked up to anything during your initial test.