Upgrading the transformer in my G7 -- Questions about PCB traces.

[CurtZHP]

I'm all confused. 

A while back, I built a G7 and instead of the Lundahl LL1538, I put in an OEP A262A3E, using tips I found here:

http://www.groupdiy.com/index.php?topic=1839

Well, now I've finally purchased a Lundahl, and I'm ready to switch it out.  The problem is that I noticed that the circuit traces for where the transformer goes have little narrow spots that can be cut through.  One of them (possibly two) has been cut.  Obviously I did that when I installed the OEP, but I can't for the life of me remember why, and my notes say nothing about it.  I'm trying to go over everything to figure it out, but all I'm doing so far is confusing myself.

Obviously, the original PCB pattern was designed to directly accept the Lundahl, but where did the cut-able traces come into play?  Do I need to bridge that?

Thanks in advance.

 

[JohnRoberts]

Just guessing... [edit-- guessed wrong}

JR

 

[ruairioflaherty]

Hi John,

The Lundahl and OEP transformers the O.P. describes are both microphone level and in the actual mic itself so not related to the PSU.

Sorry I can't help with the traces question.

 

[CurtZHP]

Actually, John, your post got my brain working.  You mentioned dual primaries and secondaries.  I downloaded the data sheet for both transformers, and the main difference is that the OEP had two primaries while the Lundahl has one.  I also noticed that the PCB trace, if left unaltered, connects both secondaries of the Lundahl in parallel, while cutting them separates them.  I then noticed on the schematic that one secondary goes to the capacitor and trimpot that are omitted from the design.

I'm assuming that the secondaries (the output side) of the transformer are to be wired in parallel.  Can someone confirm this?

 

[gyraf]

yes, primaries goes in parallel, unless you want to experiment with the cathode-feedback option (left in there for historical purposes).

Refer to the schematic and the description on the page..

Jakob E.

 

[CurtZHP]

It's all very clear to me now!  Thanks everyone!