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DIYstompboxes.com  |  DIY Stompboxes  |  Building your own stompbox  |  Boss FV-300H gutshots 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: Boss FV-300H gutshots  (Read 1508 times)
Mark Hammer
Posts: 22114


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Boss FV-300H gutshots
« on: December 03, 2012, 08:41:05 PM »

Not a lot of "guts" to this one, but there is an interesting use of slider pot for this dual-channel passive volume pedal.  You can see from the photos that the mechanism is pretty simple, really.  Move the foot treadle up and down and an L-shaped bracket moves a slider pot up and down.  The middle picture shows you that the slider knob has a little gap cut into it, into which the moving bracket fits.  Some grease in the area makes sure that the bracket does not catch on the slider knob.

And that's the key, really.  You need to make sure the slider is firmly held and that whatever moves the slider up and down has enough play in it, and enough viscosity, to follow the slider knob as much as push it.

I didn't really have an urgent need for a dual volume pedal, but it was $15.  I figured I could adapt it to some sort of filter pedal.  There's already space and holes for 4 pots beyond the in and out jacks, and a sweet little battery compartment cast into the chassis.  Seems promising.



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HAVPT
Posts: 6


Re: Boss FV-300H gutshots
« Reply #1 on: December 30, 2012, 07:02:43 PM »

Hi Mark,
Maybe you or someone who knows this pedal can help me.
I will post my question here too:

Some friend gave me this pedal a few days ago but some part is missing, I opened it and found that bigger screw with the blue glue in it, it was loose inside the pedal.
I just need to know what I'm missing at the other side of the screw just under the pedal part. On the red arrow on my picture.


Thanks in advance
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HAVPT
Posts: 6


Re: Boss FV-300H gutshots
« Reply #2 on: December 31, 2012, 03:40:34 PM »

I wish you all a happy new year! And if someone has this pedal please help!
Cheers
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Mark Hammer
Posts: 22114


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Re: Boss FV-300H gutshots
« Reply #3 on: December 31, 2012, 05:46:57 PM »

Here is a photo of the mechanism in question:


What the screw does on the *other* side of the chassis is to pull a piece of spring steel (or release it) to vary the amount of tension on the treadle.  The piece held and adjusted by the screw sits on a pivot that you show in your picture.  Adjusting the screw to pull that piece towards the screw means the other end, sitting on the other side of the pivot, will now push up against the underside of the axle.  The harder it pushes against the axle, the stiffer the pedal becomes.

Why does it need to do this?

Easy.  Because the axle is so much closer to one end of the treadle than the other, if there was no tension, the front would always go down the moment you took your foot off of it.  So, if you think of the pedal as a kind of see-saw, the front of the treadle is the 250lb cousin sitting on one end, and the pack of the pedal is the 50lb six year-old.  The tension bar is the parent pulling down on the side where the six year-old is sitting, just to make things a little more even.

Make sense?
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HAVPT
Posts: 6


Re: Boss FV-300H gutshots
« Reply #4 on: December 31, 2012, 06:12:21 PM »

Well, first i need To thank you very much for the reply.
i know something is missing here but I still can't understand what's in that picture or where will I find it.
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Mark Hammer
Posts: 22114


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Re: Boss FV-300H gutshots
« Reply #5 on: December 31, 2012, 07:05:16 PM »

You can probably make or adapt the missing piece yourself.  The important thing is that it be stiff and able to have some spring-like properties.  That is, it shouldn't snap or bend.  The important thing is that when you pull one end closer to the chassis with the screw, that the other end push up a bit so the treadle doesn't move around freely.  It shold be able to stay put where you leave it.
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HAVPT
Posts: 6


Re: Boss FV-300H gutshots
« Reply #6 on: December 31, 2012, 07:29:25 PM »

if not asking too much could you please take a closer picture on the pedal rear and front so I can observe and understand how that steel is installed on the pedal.
Thanks
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Mark Hammer
Posts: 22114


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Re: Boss FV-300H gutshots
« Reply #7 on: January 01, 2013, 03:43:42 PM »

From the first two pictures, you can see that the piece of spring steel does not stick out very far in the back, and that the pressure created by the adjustment screw pulling the front down bends it a little.  The last picture shows that  there is a little bracket fitted over the end of the steel bar that the screw threads grab onto.  You can also see in the last two pictures that the steel bar simply sits on top of the pivot point.



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HAVPT
Posts: 6


Re: Boss FV-300H gutshots
« Reply #8 on: January 01, 2013, 06:53:30 PM »

Thanks Mark, I think I understand now. I need to find that steel and the little bracket.
You helped me alot.
Thanks
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HAVPT
Posts: 6


Re: Boss FV-300H gutshots
« Reply #9 on: January 02, 2013, 03:16:25 PM »

Job done Mark, it's working well!



Thanks again!
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