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Clbraddock

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Apr 10, 2021
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68
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Columbia, MO
Heard back from Analog Classics. There was a software issue with their ticketing system and they didn't know about the order. Their representative was very nice and fixed everything. Just wanted to mention they eventually took care of me in case others saw my post and became concerned. Glad they are still in business since it looks like they have a cool selection of pcbs.
 

VK

New member
Joined
Dec 25, 2021
Messages
2
Location
EU
Loving the G9 and this forum!

How would one go about adding a jewel light for the on/off switch?
 

3nity

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Joined
Dec 30, 2005
Messages
3,598
Location
MTL, CANADA
Hi good people.
First attempt with a tube build.
I'm planning a point to point 1 channel.
I was wondering if I could use an Antek toroidal for power?
TIA.
 

lindes

Member
Joined
Aug 10, 2015
Messages
16
Location
Brussels
Hello everyone, I am a new member, guitarist and singer, and owner of a G9 bought second hand. I would like to get some advice from you for some problems I have with this preamplifier.
When I connected the G9 to my table I immediately had a humming noise on both channels. I opened the box and saw that one of the input transformer covers was next to the main circuit. I tested the other three and the cover comes off easily.
My questions are: shouldn't these OEP transformer covers be soldered to the base?
The ground loop of the box was connected to the metal part of the input XLRs. Shouldn't it be connected to one of the three XLR connections?
I am attaching photos to see what is going on.

Thanks for your help!
 

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gyraf

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Jun 4, 2004
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Aarhus, Denmark
..yes, those housings should have been soldered to the base plate under the transformers. I'm sure we talked about this many times before in this thread..

/Jakob E.
 

lindes

Member
Joined
Aug 10, 2015
Messages
16
Location
Brussels
..yes, those housings should have been soldered to the base plate under the transformers. I'm sure we talked about this many times before in this thread..

/Jakob E.
Thank you for the answer. I didn't go through the 118 pages...yet. I suppose I will.
 

zaraxisof

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Joined
Aug 2, 2017
Messages
149
Location
Greece
Thank you for the answer. I didn't go through the 118 pages...yet. I suppose I will.
It seems it's not in this thread.



This has to be done before installing and solder their pins to PCB. I forgot to do so while populating pcb so i am in the same boat as you. Shielding screening cans after having installed and soldered trafo in place. Base can be moved under the trafo. I thought it wasn't obligatory to get them stable and that gnd pin must be soldered to the base and upper housing together.
Since i built it i have them installed by just push 'em tight enough and get touched with the base by physical contact. I get continuity in DMM. Truth is i has no hum or noise problems.
Well, if i turn input and output knobs bigger than "3 o'clock" i get a little hum but i guess this is normal. Or no?

Anyway @lindes : if you find a way of how to do it without having to de-solder every pin, every trafo, please share. I tried hard in the past with no success. It's very hard to solder in the base having it between the above of pcb and under the trafo and without damaging the plastic trafo's insulation.

PS. Now that i think again of it, having the base screeining can not soldered to trafo's gnd center pin, it means it isn't grounded at all. That's why i get continuity from base to upper housing can, but i guess they are not grounded in the circuit lol.
I have to de-solder trafo? Is this safe? Or just run a cable from upper can to a gnd point?
 
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zaraxisof

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Aug 2, 2017
Messages
149
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Greece
..just run a wire from ground point to the screening can. The can solders quite easily. Don't ask how I know :)
Heh 🙂.. Yes i know, upper cans can be melted like butter with my old 50W Weller Magnastat. The base is the one that needs sanding ..
So I'll do that, run a wire from gnd to can and then another three for each other to the first one. First one will be kind of "star grounding can" to the others.
Thanks.
 
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lindes

Member
Joined
Aug 10, 2015
Messages
16
Location
Brussels
..just run a wire from ground point to the screening can. The can solders quite easily. Don't ask how I know :)
I've done that, redoing the grounding, twisted all the AC power cables and shortcut the instrument input (I don't need it). Now, I don't have anymore the heavy rumble noise. :)
 

johnchantler

Active member
Joined
Sep 21, 2019
Messages
40
Location
Stockholm
Switched my unit on for the first time the other day. Right channel sounded glorious, but left channel was crazy distorted. The D.I. inputs were also a bit noisy for both so I decided to do the D.I. shielded wiring mod for both channels. Now when I do a continuity test before switching on power I get continuity between 12V and ground that wasn't there when I powered up the first time.

I'd first tested the 78S12 to check it was not shorting through the insulation — wondered if it got a bit roughed up in moving the board around (it had been mounted on a aluminium mounting plate that covers most of the bottom of the case) so I switched it to mount on the back wall of the case.... it's not that. the short is there even when that is disconnected, so the 12V is shorting to ground somewhere else. I tried tracing that section and reflowed some solder joints but can't see anything obvious.

I have not applied power again.

Any ideas?
 

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