Cinemag CMOQ transformers in CAPI gear

[dissonantdissident]

Hey folks

I've been having a bear of a time getting my vp25 build right. Usually no problem with CAPI stuff, but this one's not been my best work. Anyway, who here has installed Cinemag output on either vp25 or vp312? I initially had a problem that I thought was having the output mis-wired (I wired the Cinemag to the pads, following the colors listed on pads/wire(just like a 2503)), but it turned out to be a stuffing error, after the rewire didn't fix the output issue and a second look at the resistors. Anyway, I was told to run the primaries parallel and wire the secondaries using the 2503 spec sheet as a guide. That meant the secondaries were moved over leaving violet and grey pads empty.

After I got the stuffing error fixed, everything seemed alright, but there's a ring or tone hum that is higher pitch than any noise my other capi units put out when cranked. Might have nothing to do with the output transformer. but that was the only thing that I can figure that could have gotten jumbled, when I switched the wires. On top of that I've seen pics online of folks that have used CMOQs and followed the pcb to wire the pads like a 2503, as I had done, originally.

Any help is appreciated.

 

[dissonantdissident]

FYI

Primaries currently wired red and yellow parallel (red pad), orange and brown parallel (brown pad)

Secondaries are as follows:
Cinemag - PCB
Gray - Blue
Violet - Green
Blue - Yellow
Green - Orange

Got my test jig assembled, last night. Will be checking voltages sent to me by another forum member, too.

 

[dissonantdissident]

Well, rewired the transformer to the pads as marked. After looking at numerous sites/schematics, it seems that the quadfilar transformers can be wound different ways, but it also makes the schematic confusing. If they can be wired all those different ways that means the second primary wind can be a third secondary wind, like the 2503 schematic shows. I don't really understand how this would work, but if anyone cares to explain it, I'd appreciate the knowledge.

Anyway, wired them back to the original configuration and it seems to be working fine (output is good and phase cancels accordingly, as far as I can tell). Still got the buzz, so it seems my issue is elsewhere. The only weird thing is that the buzz doesn't simply increase with gain. There is some noise that comes with cranking the opamp, but this is separate. If there's no mic connected, turning the gain up brings the basic opamp cranked noise, but no buzz. It only comes with the mic connected. It also seems to disappear with the pad engaged, compared to the non padded equivalent (lower gain setting but without pad). The mysteries continue!

 

[radardoug]

How is your pin 1 on the input connector wired? What is the mike and cable you are using? Have you tried other mikes and cables? Phantom?