Re: The official G9 help thread
« Reply #2300 on: March 31, 2021, 03:53:42 AM »
You'll find attached the HT psu part of the G9 schematic. This corresponds to the spare psu pcb I used. I just wired the 2nd 470uf cap (C15) to the main board at the HT pad right after the jumper. And I get 246VDC at R31 and R131 which is correct I guess.
« Last Edit: March 31, 2021, 04:20:17 AM by innercityman »


Re: The official G9 help thread
« Reply #2301 on: March 31, 2021, 12:54:29 PM »
You'll find attached the HT psu part of the G9 schematic. This corresponds to the spare psu pcb I used. I just wired the 2nd 470uf cap (C15) to the main board at the HT pad right after the jumper. And I get 246VDC at R31 and R131 which is correct I guess.

This is not what I see. I don't want to do your work. If you want me to help you, than draw a schematic exactly the way you have build it. Everything else is a guessing game...

TillM

Re: The official G9 help thread
« Reply #2302 on: March 31, 2021, 01:18:51 PM »
Why don’t you build the psu on the main board pcb ?
The Don Audio transformer has a integrated shield and is hum free.
I also used it in my builds.
I’m pretty sure, that the fault is in the wiring from the spare pcb to the main pcb.
And as RockSoderstrom said, it’s hard to guess without drawing.

Re: The official G9 help thread
« Reply #2303 on: March 31, 2021, 01:31:02 PM »
Quote
This is not what I see. I don't want to do your work.

This is not what I'm asking, I just asked for some help because I'm lost and fed up with this issue I can't solve myself because of my limited electronic skills.

The spare psu pcb I used is the one that comes with the G9 PCB kit. Jacob explained that he put it on the pcb to avoid loosing space. It is an exact copy of the onboard HT and 12VDC PSU. I only used the HT part of it and let the 12VDC and 48V on the main board. As I wrote before, I had the same issue with HT psu on the main board. The only difference with the schematic is that I've replaced C14/C15 100uf 350V with 470uf 400V caps like advised.

I'll try to draw a schemo, not sure I can do that.

Re: The official G9 help thread
« Reply #2304 on: March 31, 2021, 01:39:41 PM »
Quote
Why don’t you build the psu on the main board pcb ?

That's what I did first and same smoking diodes issue. I decided to build the HT psu out of the board using the spare one because I've read that it could help with hum issue. I'm sure my wiring is ok, it comes from somewhere else. Probably from the big HT caps like rock soderstrom said. And I'm also sure that if I build it back on the main board like I did first, I'll have the same smoking diode.

Anyway, as I said, I'll try to draw a schemo.

TillM

Re: The official G9 help thread
« Reply #2305 on: March 31, 2021, 02:04:48 PM »
hmm ... in my opinion the yellow cable from the power trafo must went to the heater, cause the heater needs at least minimum 1A. Now it works with 0,5A, cause you use the blue cable, which should go to 48v phantom.

Edit: I realize that you nearly has a problem with the preamp since a year.
« Last Edit: March 31, 2021, 02:09:59 PM by TillM »

Re: The official G9 help thread
« Reply #2306 on: March 31, 2021, 03:55:47 PM »
Quote
I realize that you nearly has a problem with the preamp since a year.

In fact I went to another project MK47 (U47 clone which has been a success and very fun build) so I let it out for a while and came back to it few weeks ago.

Re: The official G9 help thread
« Reply #2307 on: April 01, 2021, 09:47:14 AM »
Both hum and smoking diode issues solved !

The hum issue was due to non shielded audio cables, and no smoking diode anymore after replacing both 470uf 400V caps by 330uf 450V caps. So my outboard psu build and wiring was good as I thought.

Thanks to rock soderstrom for putting me on this path of investigation.


 

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