NPN Rangemaster conversion

[midwayfair]

Edit: This problem is solved. On Brian's board, for an NPN transistor, all you have to do is connect the +9v to the board where the -9v would have gone, and wire the switch and jacks as normal for any other negative ground effect from there.

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I've googled myself silly and I've found a bunch of forum posts with dead links. I'm sure someone here has done this, so any help is appreciated?

I'd like to convert the MadBean rangemaster board I have to NPN. I have an NPN transistor, I've flipped the 47uF caps (the positive side is facing the pot connections), and I've connected the +9v wire to the board where it's marked for -9v and moved the -9v to board ground and the jack like normal. I am not using a battery although I could change that if I absolutely cannot use a daisy chained power supply with this.

I've left out the diode thus far because (a) a lot forum posts have said that it is unnecessary if there's no danger of plugging in the wrong power supply (I don't have any positive ground connectors anyway), and (b) Fuzz central (http://fuzzcentral.ssguitar.com/rangemaster.php) in their NPN board used a reverse germanium diode because he said the silicon ones won't work. I have germanium diodes. Do I need to use one of those, or will it work without one?

Otherwise, I followed the PDF instructions for wiring up the harness.

If I plug this in right now, will anything explode (particularly my tantalum caps)?

I am not getting a reading on the top side of the caps (the side closest to the pot) and that worries me. This would be a kind of expensive project to lose the parts from.

[midwayfair]

Eh ... actually, I've decided not to press my luck and to just fix everything to the right polarity and use a battery. It's not a box I intend to use very often, so I don't *need* to use a power supply.

I'm going to leave the thread up, though, because I'm curious.

[midwayfair]

Bump for help.

I just finished Brian's standard PNP Rangemaster build. Sounds good and works like it should with a battery.

I'd like to use the other board I have for the NPN so I can use up these transistors.

Can anyone confirm that all that needs to be done is turn around the capacitors and the diode, and swap the battery leads, or does anything else need to change in the harness?

[chromesphere]

Hey midwayfair,

i was thinking of building one of these...for the hell of it i guess...the positive ground thing is a bit annoying, pretty sure you cant just flip those things around the other way though?  The circuit is set up for a PNP junction transistor?  Dont quote me of that...Anyway, it would probably be easier to build a roadrage and use the negative output instead.  Im thinking of doing that myself. 

Good luck, although this threads a month old now, you've probably finished it, played it, and now its gathering dust
Paul

[midwayfair]

Hey midwayfair,

i was thinking of building one of these...for the hell of it i guess...the positive ground thing is a bit annoying, pretty sure you cant just flip those things around the other way though?  The circuit is set up for a PNP junction transistor?  Dont quote me of that...Anyway, it would probably be easier to build a roadrage and use the negative output instead.  Im thinking of doing that myself. 

Good luck, although this threads a month old now, you've probably finished it, played it, and now its gathering dust
Paul

Sorry, I should delete my original post or alter it so I don't get anyone confused with my speculation.

When I used Brian's board, all I had to change was to connect the +9v, instead of the -9V, to the place on the board marked for the 9v in. I didn't have to turn around any caps or flip the polarity protection diode.

Wire the switch, battery snap (if using it), and jacks exactly as you would for any other negative ground pedal from that point. It works great; here's the build report: http://www.madbeanpedals.com/forum/index.php?topic=4494.msg39655#msg39655