API 312 Thread!

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Ok so I've posted a diagram of how I wired a DPDT switch ( NOT PCB MOUNT) to Fabio's board. It's colour code for the connections to the board, you can see I swapped the ground to the wiper so when the phantom is switched off the CCP1 can drain through an (insulated) link wire on the switch to ground. I upped the RPP3 resistor to 1K just to slow it down a little when it drains, I hope this helps.

http://www.twin-x.com/groupdiy/albums/userpics/phantom_drain_2.bmp

Mick
 
I'm using 24V relay instead of the original 5V. Which resistor values do i need to change?

I figure the LED resistors need to be about 2k instead of 470r. But what about the circuit around the HiZ input? Anyone who did this?
 
[quote author="mick"]Ok Flitan, 2K2 for the LED's

but your scaring me about the HiZ input I didn't change anything. :shock:

Mick[/quote]

Well i don't know if it's neccesary. Have you tried it and did it work?

I'm thinking that perhaps RDI3 and RDI4 that feeds QDI should be a little higher? But since QDI are just acting like a semiconductor relay that controls the real relay...the only negative effect i can see would be a waste of current thru emitter-base of QDI. Don't know if it could blow it?

Please enlight me. :roll:
 
I everybody !


I'm soldering my first API 312 (Fabio PCB and DOA) with Cinemag CM-75101APC input trafo and CMOQ-2 output trafo.
I have a problem for connecting the CMOQ2. I can't find any schematic or explications.
here is this trafo datasheet : http://www.cinemag.biz/output/CMOQ-2.pdf

It's my first DIY preamp with trafo, this is why it is a bit difficult for me.
It will be very helpfull if someone can tell me how to connect the CMOQ2 on the PCB and on TRS jack connector :razz:
thank for your help ! :wink:


(sorry for my vague english :oops: )
 
I don't use the CMOQ-2 myself but from the datasheet it looks like the color code should be the same as on the original 2503 transformer.
I think you could just connect it using the wire code silkscreened on the PCB.
But I don't know that much about the different transformer types so correct me if I'm wrong. :grin:
 
[quote author="flintan"]I'm thinking that perhaps RDI3 and RDI4 that feeds QDI should be a little higher? But since QDI are just acting like a semiconductor relay that controls the real relay...the only negative effect i can see would be a waste of current thru emitter-base of QDI. Don't know if it could blow it?[/quote]

Mick, how is it going?

I've done some reading about voltage dividers but am still quite new to this. I tried RDI3=470k and RDI4=68k which would give an emitter voltage of about 3V with 24V supply, i think.. It seem to work properly but i will do some measuring when i find the time to..
 
Sorry Flitan I forgot, I just put them together and checked the mic input's and started to look at my next project (they're mounting up on me), I'll put one on and stick a guitar in it and see.
 
Ok when I plug in a guitar ( passive pick-ups) into the DI input it work's, however after a little while (less than a minute) the temperature on Q8 on my BC boards goes up, I mean so I can't keep my finger on it is that normal ?
 
[quote author="mick"]Ok when I plug in a guitar ( passive pick-ups) into the DI input it work's, however after a little while (less than a minute) the temperature on Q8 on my BC boards goes up, I mean so I can't keep my finger on it is that normal ?[/quote]

That doesn't seem good.. But i don't think it has anything to do with the DI switch circuit. What about the QDI transistor?
 
[quote author="mick"]Hi, can somebody help me here please, I'm trying to implement the mod to allow the capacitor to drain through the phantom LED, is this the correct way to wire a SPST switch onto Fabio's board to allow this to work ???.

normal_PP.jpg


Thanks Mick[/quote]

Tis is soo weird!! I really cant see why this doesn't work?? I did the same, just connect the diode to +48V with 5k6 resistor. When phantom is off there's about 1V still going to the mic.. I also connected the diode to ground on the main card, not the switch ground.

I will try your other solution with the shorting switch today.

About Q8, there's no heat problem on mine with a giutar connected.
 
As long as we are on the topic of switches for this project: I have the PCB mount switches that are the toggle type. I noticed, once everything was pretty much stuffed and mounted, that the down position turns Phantom, Pol, and Pad to ON, and the up postition is OFF.

Is this correct, or am I just going looney? I do have a patch idea for it, but I don't want to implement that until I'm sure it is backwards from what I want. (UP=ON and DOWN=OFF)

Thanks.
 
[quote author="Arrigotti"]I noticed, once everything was pretty much stuffed and mounted, that the down position turns Phantom, Pol, and Pad to ON, and the up postition is OFF.[/quote]
this is correct. you can mod it to be backwards - I did it in mine.
 
So I finally got everything together, and fired up the unit.

I am using Bauman's PSU with the 5V regulator for the relays. I am reading 5volts with no load for the 5volts part of the PSU, which is good, but when I put any load on it, the voltage goes down. With only 1 LED, the voltage drops to 2.2V. If I engage any of the relays, the voltage drops to 0V.

I tried replacing the regulator thinking that is may be bad, but it still does the same thing.

I have 44.5Volts at the Phantom power regulator, and that doesn't change at all, even if I load the 5V section.


Just as a note, I did have a diode in backwards upon first fire up (D13), but I changed it to a new one and reversed it to the correct orientation.

Any suggestions?

Thanks.
 

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