G7 Questions

[FoundationSound]

Ok, just a few questions regarding my G7 project.

First off, I got my components list/part numbers off of this forum somewhere a while back, I can't remember where but there were apperantly a few typos. The first was the wrong part number for the lundhal transformer (which I got straightened out), the second only called for (1) 1g resistor (which don't quite fit the pcb but i'll live), when in fact the project requires two, and the third problem I think I found is this particular parts list says that I need (12 quantity) 16.5k 1/2w metal fim resistors. why? I don't see this at all on the original parts list let alone 12 of them. (This is what I ordered.)

My second question is where the second 2u2/160V Polyester Capacitor goes on the mic. I see 2 on the schematic and the parts list and I'm wondering how I need to place the second one in the mic body.

My third questions is this... there's a couple of pads in the middle of the pcb that don't seem to connect to anything (like islands), i think they're for the feedback option but i just wanted to make sure. On the original prototyping pics on the Gyraf website there are 2 resistors soldered together just to the left of the 220u/25V capacitor that are close to that area of the PCB.

Which brings me to my fourth question, the PCB layout shows a 220u 25V capacitor between the 1.6k resistor and the 220R resistor, but I don't see one on the original parts list. Am I blind?

If this is too vague of a description I'll try to get some pictures of my project up.

I think that's all my questions, sorry I have so many but this is only my second real project and I just don't want to screw anything up because I already have several hundred bucks / hours invested in this thing. Any help is appreciated, thanks for your time.

 

[FoundationSound]

No Love.

 

[sbranco]

I can't answer much of what you ask but I think the twelve 16.5K resistors are for the power supply. Whoever made up that parts list was probably modifying the original 3 pattern switch using a 12 pattern switch instead that is used in many mics today like the Apex 460 and Nady 1150.

If you take the overall resistance for the 3 pattern and divide by 12 I think you get 16.5K. That is what you need to use if you ordered a 12 position switch for the pattern selector on the psu.

If you haven't already you should look at the meta meta at teh top of the page and then for all things g7 related. You might find some more answers there. For example, the 16.5K resistor thing is buried in there or I wouldn't have had a clue.

 

[FoundationSound]

Thanks, that answers that question. Hmmm, I might just go get a 3 pattern switch to save myself the hassle. What's the advantage of using the 12 pattern switch?

I did a search for G7 related topics and came across a few answers, some of which got deleted before I posted this question but couldn't find the others.

 

[BR]

Hey There,
I think you got my parts list and you are right about the 1G resistor. You need two for the project.
sbraco was on the ball. The 16k5 resistors is for a 12 pattern set up. I'm using that, so I can have more options when using the mic, specially in large rooms where a little bit more pattern control can come in handy.

Lundhal should be the 1538, correct??

take care
Gil

 

[FoundationSound]

Yes sir, 1538. What do I need to do differently when wiring that 12 way switch compared to the original schematic?

 

[sbranco]

Again I am not really the person to answer this but it looks like right now, I'm all you've got.

The 12 position switch doesn't appear to be appreciably harder than the 3 position switch. Its just changing the voltage going out the pattern control.

On my Apex 460, there are small resistors soldered from position to position in a circle around the switch (which would be the 16.5K resistors in this case) You make the same connection to and from the switch. The switch in different positions adds more or less of the 16.5 K resistors thereby changing the voltage going to the pattern selector part of the circuit.

I am pretty sure its that simple and not that hard really. Just a little more soldering and a slightly more expensive switch. It would be harder to get a different switch and resistors if you've already got the switch and resistors for the 12 pattern.

You can do a search but looking for the G7 meta can yield things you might not find in the search.

 

[BR]

Hey Foundationsound,
Just don't populate the 2 100k resistors on the power supply pcb. (the ones next to the pattern switch on the schem). And use a Lorlin 12 pos rotary and connect the 16.5k in series on the rotary. I'm pretty sure you can figure out the rest by looking at the schem.

take care
hope it helped.
Gil