Some G9 questions

[tony dB]

Don't know for sure about the temperature

i found them here

 

[louder]

alo
this is what i did,as told by jakob:isolate the vr from the chassis.
put isolators on the screw holes,both sides.solder the wires in the vr pins.
don`t forget to do some holes in the box,so heat gets out of the box.
did all this,and never had a single problem with g9.
great pre,this g9.used them today for mic rooms(drums),and got a balanced kit,with lots of air.
best regards
pedro

 

[dukasound]

Hi Pedro
One more time thanks for G9 caps.
This is a good guy, folks :!:
Duka

 

[EEMO1]

umm... im confused a little. how is the base of the chassis supposed to conduct the heat if the vr is isolated?

i think my heatsinks are a bit small. i think i may need bigger ones...

what's the big hole in the tube socet area for?

 

[Gus]

Often Thermal grease and a mica pad or a thermal pad designed not to be use with grease.

Often the holddown screw is insulated with a plastic bushing


Look for the heatsink thread from yesterday

 

[gyraf]

[quote author="EEMO1"] what's the big hole in the tube socet area for?[/quote]

Some tube sockets comes with a centre (ground) terminal..

 

[EEMO1]

any benefits in grounding the tube socket? and where should it be grounded?

-eero

 

[dukasound]

Hi
Can I use this kind of wire (except on place where are used shielded cable) on G9 and other project where we have many connections between two boards etc.

Duka

 

[EEMO1]

finished my g9. works, but only 1 channel works. input tube on channel 1 (v1) doesn't heat up. can this be the problem? i think the socket may be badly soldered...

how do i discharge the unit? im scared to go back in there... any help is appreciated. how do i measure it's safe?



channel 2 works and the sound is good. no hum, distortion or anything. im happy about that.

thanks,

eero

 

[Emperor-TK]

[quote author="EEMO1"]finished my g9. works, but only 1 channel works. input tube on channel 1 (v1) doesn't heat up. can this be the problem? i think the socket may be badly soldered...

how do i discharge the unit? im scared to go back in there... any help is appreciated. how do i measure it's safe?



channel 2 works and the sound is good. no hum, distortion or anything. im happy about that.

thanks,

eero[/quote]

Eero,

No heater = no sound. This is most likely your problem. When probing to see if there is any charge stored up in your caps, clip the neutral lead of your meter to ground, and then probe for voltage with only one hand. It's safer that way, since you arent making a pathway from one hand to the other (through your heart). Tie your other hand behind your back if it helps. :wink:

It looks like all the HT caps can bleed to ground through the resistors around the TL783. The only one I'm not sure about is C14. I'm still learning though, so perhaps one of the electro-jedi masters can fill in the blanks.

Regards,
Chris

 

[Gus]

maybe this will help


http://www.groupdiy.com/index.php?topic=5168

 

[EEMO1]

tk,

thanks for the info. i know the one hand thing already

what beats me is what i can touch and what not. in this case i need to re-solder the tube socket. so obviously i need to remove the tube and take the board out and such.

more info would still be appreciated... im gonna do something tomorrow.

-eero

 

[Emperor-TK]

[quote author="EEMO1"]tk,

thanks for the info. i know the one hand thing already

what beats me is what i can touch and what not. in this case i need to re-solder the tube socket. so obviously i need to remove the tube and take the board out and such.

more info would still be appreciated... im gonna do something tomorrow.

-eero[/quote]

I wouldn't work on any high voltage circuit untill everything was discharged. Check the HT caps first. If any are still holding charge, you are going to want to discharge them to ground through a resistor. I would probe the 2W 470 ohm resistors on each side of the TL783 first to see if there is any voltage there (R33 and R37). I won't promise that there is no charge stored anywhere else, especially if some other mistake in the hook-up somewhere. Probing everything from the top of the board is safe if you are using the one-hand rule. Follow the schematic and you can probably find a connection to each capacitor on the top of the board, possibly through another comnponent lead, like a resistor (or a jumper). Of course if you do need to bleed charge through an external resistor, just be carefull how you hook it up so you don't get shocked. Bigger resistors will drain charge slower and wont draw as much current.

Regrds,
Chris

 

[EEMO1]

i managed to resolder the socket and the tube started working. but still no sound...

i was wondering, i can manage with only one channel... can i take the oep's and tubes, control boards and such out of the not-working channel? i was thinking if i could use them in another project.

thanks,

eero

 

[dukasound]

Hi
I asked on my last post about this:
Can I use this kind of wire (except on place where are used shielded cable) on G9 and other project where we have many connections between two boards etc.

Also does 4 wires from small to main boards (who are connections transformer to phase switch) must be shielded od maybe twisted.

One more question ( I am suppose not stupid) :?
Is signal in phase in left position of phase switch :?: I saw on frontpanel - and + not in phase and out phase.
Thanks
Duka

 

[EEMO1]

duka,

i used wire like yours...

-eero

 

[dukasound]

[quote author="EEMO1"]duka,

i used wire like yours...

-eero[/quote]
Thanks
Question about phase switch :?:

 

[mhelin]

[quote author="Jazzy_Pidjay"]hi

i have a melodium trafo (1:8 found with my tests)
from my founded mixing desk.

i wanna know if 1:8 is to high for
the G9 inputs ?

the trafo sound very good !! very natural
with just a little little smooth high end
(tested in loop with the A/D D/A...)

thanks ++[/quote]

Also I'd like to know if Lundahl 1530 could be used as G9 input trafo (it's 1:3.5 vs. 1:2.5 of 1528). Does the 1:6,25 on schematics refer to impedance ratio? Then the LL1530 is 1:12,25 trafo.

 

[gyraf]

Transformer ratios are ALWAYS turns ratios, not impedance ratios - unless they're marked 600:600 or the like.

You'll need to do some experiments on your own, if you want to change parts to other types.

Let us know how it turns out...

Jakob E.

 

[madreza]

Sorry for my "stupid" question but
how do you reverse an oep transfo ?
:?