Boss NF-1 to SG-1 conversion

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puppiesonacid
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Post by puppiesonacid »

ansil wrote:[ Image ]


ok the box outlined in red i pretty much recommend to just remove and or reuse for the components. notice the two arrows in yellow cut traces to ground and use two wires to flip this.
change the 33k to a 47k tie it to the gate of q3

the caps in purple would probably just be better to mount on top of the board. connect points z together. change 2M pot to a 20k

lost the original one due to some crazy windows seven error this was a fast and dirty redo hope it helps

Can the pic with the noted changes be reposted or retrieved by any chance?

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ansil
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Post by ansil »

Not quite sure what you mean the picture still there I clicked on the image link and it works fine

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puppiesonacid
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Post by puppiesonacid »

is it possible to do this type of
mod with any analog noise gate?

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Post by JiM »

Pretty much.
You need to figure out how to set a slow attack in the side-chain, depending on the particular operating principle of your unit.
I only give negative feedback.

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Matlevo12
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Post by Matlevo12 »

Hi.
I just did this conversion. For me there are some aspects missing in Asil's picture (post #13 viewtopic.php?p=153306#p153306).

My NF-1 was an earlier version than the ones I could find a Service Manual to, it's a little bit different.
The PCB looked like this :

Image

Main differences, among others, which make it closer to an SG-A by the way (according to the service manual I could find anyway) :
- the led driving transistor Q10 on the top left corner
- the first resistor to half-voltage (left of Q1, see service manual) was already 470k
- the 33n cap come before the 1M resistor between Q3 and Q2

Here's how my successfully modded NF-1 looks now. I had to drill holes, make some bigger to fit several components leads inside, cut or link or reuse traces, etc. O also took the opportunity to replace all electrolytic caps and change them to film caps when in the signal path, and to get rid of the PCA/ACA 12V/9V diode and resistor.

Image

Image


In order to help others, I corrected Asil's modified NF-A schematic, here's what I added / modified (if I still manage to remember all of them well !) :
- wrong components values
- two 1µ in series between Q1 and Q2, direct connection to Q3 in between them
- pin 2 of the IC going to resistor (390r not 680) and 1µ cap to ground, not to half-voltage
- clarified and corrected the whole Q5/Q6/diode added part of the circuit mayhem
- clarified what was connected to the Decay (attack) pot.

Just to be clear : I didn't take the time to understand how the circuit works, I don't know if all the changes I added are necessary (I do now that if pin 2 goes 680r and 1µ then to half-voltage rather than ground that doesn't work, though, since I hadn't seen that difference between the two circuits at first). What I do know is that now I have SG-1 copy that sounds how it should, even if it wasn't easy :)

There you go :

Image

Have a great day everyone !

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Post by 2sc1815gr »

A big THANK YOU to everyone on this thread. After abandoning this mod last year, I was able to finally get my head around it
and managed to get the mod done! THANK YOU!

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ansil
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Post by ansil »

Thank you Matt
I truly forgot about this thread for some reason I was not getting messages from the forum I fixed it now I think I had somehow messed up my email.
I only did a few of these back in the day and each one had to be tweet to do to board variations.

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Post by Chistopher »

Thank you Matlevo12, I think I'm near close to the level of confidence I need to fulfill this mod.

Would it be possible for someone to list out the steps to complete this mod according to the schematic so a dummy like me and other people who stumble upon this can know what to do? Modding a NF-1 is a very cost friendly way to get an SG-1 in the current market, and this thread is the closest we have on the internet to any documentation.

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Post by Chistopher »

What are the green Z's for one?

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ansil
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Post by ansil »

The green z was to show you 2 connections without extra wires.

Btw there is an easier way than doing this mod. Use an existing boss case and get one of the boards from many many makers out there.

If you do it just right you can fit a tpdt switch in place of the momentary.

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Post by Chistopher »

Ah, that would make sense. I'm going to try and do it any way just because I acquired a NF-1 as part of a lot. I'll try to document it and put it on here

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Post by implant »

Chistopher wrote: 07 Feb 2024, 17:18 Ah, that would make sense. I'm going to try and do it any way just because I acquired a NF-1 as part of a lot. I'll try to document it and put it on here
Did you happen to try this yet? Also acquired a NF-1 and would be interested to see the process

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