EAR phono pre problem ??? Help needed..........

First schuffle tubes to identify the bad one...

does anyone know which tube socket is for which channel?

Hmmm...this does not sound like a tube problem. Sounds more
like one of two problems:

1) a cold solder joint going intermittent; or

2) The volume/gain pot or the MM/MC switch is dirty.

First swap the tubes to see if one of the tubes is faulty.
If not....

I would first try to eliminate possibility #2 as it's easy.
Next time this happens turn the gain knob up/down and flip
the MM/MC switch (make sure system volume is LOW!!!). If you
hear any sort of crackle or channel loss/regain get yourself
a can of Caig Deoxit and clean the pot/switch.

If it's a cold solder I would send the unit in for service.
My old MAC-4100 showed the exact same symptoms. Cleaned all
the switches and pots but no luck. Sent it in for service
and sure enough they found a cold solder joint...it took
them 5 hours on the bench to find it!

The unit hasn't done it again. However I did notice a small crackel noise in the gain knob. Very slight but it is noticeable. Maybe I need to clean the pot switch as directed by Meisterkleef. I swaped the tubes prior and well maybe that's why it hasn't happened again. Or the switch just has some dirt on it. Thanks for all of your help in the matter too...........

Hello Zenieth, I had the same problem w/ my EAR last month,
Turned out to be a bad tube ( V3 which I understand to be the cathode follower)
Good Luck

Zigstien

Zigstien,

Thanks for the response. What did you replace it with? All three of just the V3?

Hello Zenieth, I replaced V3 only w/ a sovtek 12ax7LPS.
in V1 and V2 I've been using Mullards 12ax7.

Thanks Zigstien..............