First power up of G9...

[monty]

Well it seems to work, well...sort of...

I have used shielded cable on the 5 pin connectors. The shield is terminated to ground at the nearby TRS connector. However, on the very last gain setting on the right channel, there is extreme oscialltion.

I know this isnt a new problem ,so what other solutions besides shielded cable have others come up with for this ?

Also. is it normal that I should get a signal through the instrument jack when the selector is set to MIC. ?

Thanks in advance...

 

[matthias]

yes it's normal to get a signal in the "mic" position...

have you only shielded the cables, or have you cut the trace that goes to the connector on the pcb??

 

[monty]

[quote author="matthias"]yes it's normal to get a signal in the "mic" position...

have you only shielded the cables, or have you cut the trace that goes to the connector on the pcb??[/quote]

Only shielded cable for the 5 pin connectors, thats it.

Dont know if I like the idea of ripping the board out, then cutting traces...

Have you done this, how involved is it ?

 

[monty]

If I disconnect the shield from ground and hold onto it, the oscillation disappears..

hmmmmm,. thats gotta mean something.

I know there is reason why this happens, but I cant remember why. :grin:

 

[monty]

[quote author="matthias"]yes it's normal to get a signal in the "mic" position...

[/quote]

AUDIBLE signal though, Matthias ??

 

[matta]

I think the answer lies here: http://www.groupdiy.com/index.php?topic=9668

Cheers

Matt

 

[monty]

Thanks Matta,

hmmmm,

dont like the idea of cutting traces myself, Man I dont know, itsa frustrating, as it works perfectly otherwise..

I might try and think of something else.

 

[alk509]

[quote author="monty"][quote author="matthias"]yes it's normal to get a signal in the "mic" position...

[/quote]

AUDIBLE signal though, Matthias ??[/quote]

Why wouldn't it pass signal? Have you looked at the schematic?

Peace,
Al.

 

[monty]

[quote author="alk509"][quote author="monty"][quote author="matthias"]yes it's normal to get a signal in the "mic" position...

[/quote]

AUDIBLE signal though, Matthias ??[/quote]

Why wouldn't it pass signal? Have you looked at the schematic?

Peace,
Al.[/quote]

Well Im just learning this stuff so....

Ill look at the schem again..

Just trying to understand why have a "line" switch position, if the inst. input will work anyway in the "mic" switch position.

 

[alk509]

[quote author="monty"]Well Im just learning this stuff so....

Ill look at the schem again..

Just trying to understand why have a "line" switch position, if the inst. input will work anyway in the "mic" switch position.[/quote]

Gotcha. The instrument input is located after the input transformer and it's not affected in any way by the input switch, which is pre-transformer. The 'mic' position sends the signal straight to the preamp. The 'line' position puts a (20dB? can't remember) pad at the input, so you don't overload the preamp with more signal than it's expecting when you plug a line-level source on the transformer input.

Peace,
Al.

 

[monty]

Ah!! Thanks Elk! That makes alot of sense, and looking at the schem, I can easily decipher what you are saying, so thanks. :grin: