EF-1

[Mojofilter17]

I know the EF-1 schematic is not in our database, but anyone out there have one or know where to get one?
Thanks!

[roberto]

Can you explain the problem of the unit? Some might have a clue of what's going on.

[Mojofilter17]

No power on the unit. I could probably figure it out once the unit arrives (belongs to a friend), but just like to be ready with a schematic. Unless it's the transformer, should be fixable.

[AnotherJohnson]

Check for a blown fuse.

From the manual:

The AC line is fused to protect the EF1’s transformer. This fuse will not fail in normal operation. Failure of the fuse is a symptom of a more serious problem, indicating the need for qualified service. In no event should the fuse be replaced with a fuse of different type or rating than that supplied by the factory. The EF1 uses a 1/4 amp 3AG fast-blow fuse (1/8 amp 3AG fast-blow for 220V operation).

[roberto]

AJ is right! Use the only recommended fuse rating. On no other circumstances you should use a higher fuse value.

[Mojofilter17]

The main power fuse upstream of the transformer was blown. I began checking the power supplies - the first regulator after the rectifier/filter is a Darlington pair, and the MJE340 was shorted emitter/collector. With the MJE340 pulled, the downstream path was still shorted to ground. I lifted the side of the large filter capacitor on the output of the Darlington pair and viola! Short gone. I removed the Conrad-Johnson-made 2.0 MFD 100VDC cap and found it dead-short between the leads. I have to say I was quite surprised. I guess I thought the C-J caps lasted forever.
Conrad-Johnson will not sell me a replacement so I put a SCR polypropylene of the same value in its place. I believe SCR is supposed to be a good cap, and this one is not in the signal path so I figure it's good to go.
This EF-1 is dead-quiet!! The EQ curve is spot on. Very airy and transparent.
Thanks all for your input!

[admin]

Congrats. Glad it was a relatively easy fix. Enjoy the music.

[AnotherJohnson]

The CJD Teflon caps would probably last longer, but 27 years is a good run for the other plastics.

Congratulations!