innercityman

N
« Reply #2220 on: May 07, 2020, 03:44:34 AM »
Thanks TillM,

I used the expensive one, but the spec seems to have changed in the newer version. Here's what's written on mine :

secondaries :

Red 275V 0,14A
Blue 12V 0,5A
Yellow 12V 3A

I saw pictures on the net of builds with the older version of this transformer and I saw that blue was 15V 0,3A . Would it change anything ?

And I did the correct wiring... Blue to 15VAC and yellow for 12.

But guess what... I've posted my problem on a Facebook group dedicated to pro audio, and a guy contacted me saying that he has exactly the same problem with exactly the same power transformer bought at don-audio.

I'll change the diodes D17 to D20 and see what happens. If it blows again, I'll try with the classic two transformers build.


TillM

Re: The official G9 help thread
« Reply #2221 on: May 07, 2020, 12:19:07 PM »
Strange ... diodes d17 to d20 are for 275VAC area.
In my mind the 12VAC 3A are for the heater section. (Jakob prove me if I’m wrong)

innercityman

Re: The official G9 help thread
« Reply #2222 on: May 08, 2020, 03:06:07 AM »
The guy who gets the same issue on FB told me yesterday that he contacted don-audio and they said that blue is 15V, not 12 like printed on the trafo, it's a printing mistake. He also said that he is pretty sure that the problem comes from the 220V. D5 zener has strange measurement on his G9.

I fired it up yesterday and no smoke. (strange). I've been able to put a mic on it and both channels work, but I have a hum on both sides. I suspect a ground problem. Here's a picture of my build...

TillM

Re: The official G9 help thread
« Reply #2223 on: May 08, 2020, 03:47:34 AM »
Your grounding is wrong.
Just connect pin 1 from the input xlr with ground from IEC.
You separate it. That will causes ground loops.
Why you connect booth 12VAC wires to the pin ?
Your other 12VAC has no connection.
(Connection next to 275VAC)

innercityman

Re: The official G9 help thread
« Reply #2224 on: May 08, 2020, 05:04:45 AM »
For the ground connection, this is what I was thinking about and decided to modify it today, so thanks for confirming me that. For the yellow 12V...

Quote
Why you connect booth 12VAC wires to the pin ?

What do you mean ? Do I have to connect only one wire and let the other floating with heat shrink ?

Quote
Your other 12VAC has no connection.

You mean the 15V blue wires ? They are connected to a socket. They come from under the PCB that's why you can't see it on the picture.

innercityman

Re: The official G9 help thread
« Reply #2225 on: May 08, 2020, 05:14:44 AM »
I connected the trafo as it's indicated on don-audio's page for European 230V rating


TillM

Re: The official G9 help thread
« Reply #2226 on: May 08, 2020, 06:57:25 AM »
For the ground connection, this is what I was thinking about and decided to modify it today, so thanks for confirming me that. For the yellow 12V...

What do you mean ? Do I have to connect only one wire and let the other floating with heat shrink ?

You mean the 15V blue wires ? They are connected to a socket. They come from under the PCB that's why you can't see it on the picture.

Thanks, I need glasses, I don’t see it first, that they went underneath the board.
The Hum should gone with new grounding.

innercityman

Re: The official G9 help thread
« Reply #2227 on: May 08, 2020, 09:51:11 AM »
But you didn't answer my question about the 12V wiring...?

Quote
Why you connect booth 12VAC wires to the pin ?
Quote

Quote
What do you mean ? Do I have to connect only one wire and let the other floating with heat shrink ?

TillM

Re: The official G9 help thread
« Reply #2228 on: May 08, 2020, 01:27:12 PM »
But you didn't answer my question about the 12V wiring...?
Your wiring from the power transformer is correct.

 

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