[NJARC] Hi, Guys. What am I looking at here?

[Dave Sica]

On Sun, 15 Mar 2009 07:27:19 -0700 (PDT) John Ruccolo <jr6v6gt at yahoo.com>
writes:

Thanks for the suggestions, all.  I'm looking into it but haven't nailed
anything down yet. Anyone with any other ideas while I'm at it?

> 1) Tell the young lady to forget it and buy an Ipod! (like everyone 
> else her age)

I had suggested that she get one of those USB turntables so she could
play the 78s into her iPod. She made it clear that actually spinning the
scratchy vinyl (or in her case it's the shellac she likes) was the
experience she was looking for. 
Aren't you just charmed by that?

> 2) Does the behavior change when you reverse the AC line plug? 

That's the first thing I tried, along with shutting off all the
fluorescent lights and dimmers. No luck there.

> 3) It may be that the volume control just needs more cleaning. 

Since the volume control is relatively noise-free AND this noise spike
raises and lowers smoothly as the setting of the volume control is
changed I'm pretty confident a dirty pot is not the issue.  The fact that
the noise goes DOWN first, nulls out and then raises as you rotate the
volume control clockwise still has me scratching my head though.

> 4) Is there a preamp stage (like a 12AV6 or something) before the 
> 50C5? 

There is a 12AV6 preamp. I'll poke around in there.

> 5) Possibly the cartridge wiring? 

Aaron said "Make sure the connections at the cartridge are tight and
wires properly 
soldered and not broken. The leads can act as an antenna. "

This strikes me as perhaps the most likely culprit based on what I'm
hearing. And it's definitely not something I thought to check before.
Thanks, Aaron.

> 6) Try swapping out each tube one-at-a-time -- I wonder if you could 
> have heater/cathode leakage somewhere? If there was a H/K *short*, 
> however, I would expect a LOT more HUMMM.

The 60 cycle hum is not really objectionable. This morning, the buzz is
also a lot less noticeable. Probably back to the level it was yesterday
during the day when I couldn't really even notice it at normal playback
levels.  I wouldn't expect a short here to generate or allow primarily
the HF noise to get through but someone please correct me if I'm wrong
about that.

Darren suggested H-K arcing. I'd be surprised if there was enough
potential there to strike an arc, plus this is a VERY regular pulse, not
random at all as I would expect an intermittant short to sound.
 
> As a vinyl collector for over 30 years, are you telling me now I 
> have to compete with people MUCH LESS than half my age? Sigh....no 
> wonder I'm not finding anything at the local second-hand store.

Much, much less than half your age and very very into this. Hey, we talk
about encouraging young people to get into aspects of our hobby. Now be
careful what you wish for!

Thanks,
--Dave
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