mic input transformers internally shorting? Reliability?

[Guest]

Hi there,

I've done some searches, but no direct answers found, so...sorry if this is redundant on the board:

I just swapped out an altran mic input transfo for a cinemag, and dug the sound so much that I decided to swap out the other. When I did so, the output is solid 3-5dB quieter on the second swapped-out channel. So, same transformers, same power supply (hamptone jfet kit), and lower output. I swapped the altran back in to see if the gain would jump back up, and voila...more output. So my questions:

1. The second transformer came off of an old kit board, that had seen some action...could testing, troubleshooting, shorting a board damage a transformer and reduce the step up voltage gain? I only ask 'cause I've read that transformers are pretty robust, but...?

2. Anybody ever get a bad transfo (i.e. defective out of the box)? The altran I swapped out first was internally shorting everything to ground. I can't look inside to verify this, but when in the circuit, it had no resistance from pins 1-4 to 5-8...which I'm assuming (and perhaps mistakedly) is primary (pin 1) to secondary (pin 5)? This showed up when measuring 40.3DCV for phantom, only when the switch was engaged. Sorry for the ignorant guess-fest, I should know how the primaries and secondaries are pinned!!!

Thanks. I know it's work answer newbie questions, sometimes.

Kelly

 

[CJ]

I'll fix it.
Trust me.

 

[Guest]

:?:

I guess I'm pretty loss if I have to ask...

 

[jrmintz]

I had a new Carnhill input transformer that had an intermittent short between the center tap of the primary to ground. One of these days (real soon now! :green: ) I'm going to get around to trying to fix it. But yes, they can be broken out of the box.

 

[soundguy]

you cant do anything until you figure the pinout on the transformer.

then you need to remove it from the circuit to test it.

If its an altran in a can, did you mount it directly to the board or did you putu a barrier between it and the PCB? Are there any traces running under the pcb which would be shorting against the can? Is the can the type where you may easily solderbridge a pin to the can by accident?

figure out the pins then take it off the board then test it. You can have a bad transformer or have 100 other things going on, eliminate the variables.

dave

 

[Guest]

Yo Dave! Man, it's been awhile.

Yeah, the pins I did find were in fact 1-4 and 5-8, primary to secondary relatively. And yeah, it was the transformer. I tried reseating it, a little jimmy here/there, heating up everything on that side of 6.8k resistors, etc. and nothing. Swapped in a cinemag trans and voila! It became pretty obvious there was something weird with it when there was no resistance primary to secondary (when wired in the board). Go figure.

Scott Hampton, the gentleman that he is, was eager to replace, and to take a look at to gather info. It's going on the 3 years or something since my first hamptone kit, and that guy is still the nicest guy in showbiz.

kb