Measuring A Capacitor

OK, I did the shorted IC exercise, and there was no hum. What does that tell me?

Can I just make shorting plugs with an RCA cable I don't mind sacrificing?

The IC to every input didn't work, so now I'm on to shorting the ICs. We'll see... Do I need to turn anything off while I'm doing this? I'd hate to damage my Vandersteens while performing this. Also, I have a question. Someone thought a cap is going bad, hence the buzzing. If a component like that is bad, shouldn't the buzzing be present constantly? For me, there are times when the buzzing is totally absent.

In order to be perfectly clear, I:

Turn the stereo off
Put the shorted IC in place
Make sure Phono is selected as the input
Turn the stereo back on
Turn my house into a smoldering pile ashes (just kidding)
Listen for the dreaded hum on the phono input

Thanks for all your help.

Lee

Well, I tried the suggestion clarified by Herman. Buzzing still present. Now, I am going to try shorting the interconnect, and see where that gets me...

The buzzing noise is at 60Hz (my guess), and is pretty loud (volume dependent). I know it's there, so I get bothered by it's presence.

Here's what I did: I used shorted RCA cables on the phono input - no discernible hum. Then I used tin foil (as a shield) between the phono cable and the power amp power cable - hum still present. Then I went wild with the tin foil, and put a few 2" squares between the phono input, and the adjacent input (tuner - unused) on the preamp - buzz still present. Then I put a sheet of it between the amp, and the preamp - buzz still present. So, either tin foil is a bad shield material, or the problem is in the preamp. Here's why I say that: the hum can be reduced, or eliminated by my touching the faceplate of the preamp. It's possible that when I did the shorted RCA plug test, the hum was gone anyway.

FYI, the TT I am now using is an MMF 2.2 LE, with an MMF Tracker cartridge (Goldring Elektra) moving magnet type. It has a 2 pronged plug. The same can e said of the NAD preamp. The amp, which is a very recent addition, is a B&K Sonata ST-140, with a detachable IEC, 3-pronged plug/cable. My old Carver M-500T was put back in place as a test - still buzzed. I used to have an old Denon DP37F in the place of the MMF. It had a Sumiko Blue Point MC on it's tonearm (and it never buzzed).

What do you think my next move should be, given all that?

Yours, in vinyl,

Lee

The hum is finally gone! The ultimate fix was a simple one. All I had to do was flip the preamp plug 180 degrees. I thought I had already done that. Live, and learn I guess. Now I have about 5,000 LPs that are waiting to get played... You all know what LP stands for, don't you? Most people think it mean Long Playing, but it really means "Licorice Pizza".

Thanks to all who contributed to my affliction with vinyl.

Lee

An update - This morning, the hum had returned, so I retraced my doings of the day. It turns out that the cause of the hum wasn't plug orientation, like I first thought. But rather, it was airborne RF interference caused by my amp. As long as there is a piece of foil between the amp and the cables going into my preamp, everything is fine.