Problems w/ mini booster 2....help please

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6/12/2000 10:36 PM

chuck

Problems w/ mini booster 2....help please built it off of rg's board using mpf102's and nte458's. i caught the different pinout on the nte458's so i don't think thats the problem (they end up mounting at 45dg. angle instead of 90) i used a 3pdt switch w/ led and used the schematic wireing diagram instead of layout (for mill. bypass). the light comes on, and the board is getting power, but there is no sound whatsoever comeing out of it. the only sound i can get out of it is by turning the trimmers inside i get the scratchy pot sound. works fine in bypass mode. measured D and G on the jfets and they have 4v and 6v going tru each one (if that means anything). ive triple checked the wireing, cap polarity, etc. heated up any questionable connections. anyone have any ideas?   thanks for your help!!   chuck

 

6/12/2000 11:42 PM

aron

Chuck, It sounds like you have it close to working. Are there trimmers in the booster 2? Anyway, if this is the booster 2 that I am thinking about, read this note: "The top two wires coming out of the board on the left should be swapped. The first one should go to the DPDT as it's the input of the board. The 2nd should go to the GROUND of the input jack - check out the board - the leftmost wire goes to a 1M resistor to ground (anti-pop resistor), the 2nd one goes straight to ground." You need to swap the left top two wires as described. I think R.G. was going to update the .pdf. Aron

 

6/13/2000 2:47 AM
R.G.	quote: "You need to swap the left top two wires as described. I think R.G. was going to update the .pdf."   He did, when we talked about it last. It's been correct for the last bit. Maybe he's working with an old printout?

 

6/13/2000 4:54 AM

chuck

nope, those wires are correct ive got the switched wires wired correctly, so thats not it. and yes, the minibooster 2 has to 10k trim pots in it. I used the piher brand from mouser. everything looks correct. the dpdt wiring on the layout is different then the schematic, and thats the only thing that has me worried. i followed the schematic since im familar w/ the wiring it uses. the layout wiring is for the mill. bypass and has a diagonal jumper (etc.) instead of the way i followed w/ the jumper straight across. anyways, if no one has any other ideas i guess ill swap some parts and see if that does anything. I guess no sound at all is better then sounding bad. thanks for your help!   chuck

 

6/13/2000 8:36 AM
aron	I would start tracing the input signal from the jack and make sure it goes into the board. Also, triple check your orientation of the FETs.

 

6/13/2000 6:11 PM

Jake

Chuck,     Try this: Desolder the center wire of your Volume pot at the stomp switch end. Now unsolder the PCB end of the wire going to the center lug your drive pot. Solder this wire to the DPDT switch so that your drive pot is now connected to the DPDT. You should have bypass/ 1st minibooster. The drive pot will work like a volume control when going through the minibooster. This will simplify your challenge, and the point is to now make that first minibooster working. (This is a little trick I learned from RG not too long ago!)     As Aron, says, triple check everything... values, orientation, polarity. Measure resistances across resistors from the solder side of the PCB. And hit all your soldered leads with an iron just to be sure, being on the look out for solder bridges. If you have no signal, this may mean either a short to ground or a bad solder joint.     If the minibooster works then your problem is in the tone circuit or second minibooster.     Jake

 

6/13/2000 6:28 PM

aron

Good ideas. If Chuck uses the audio probe mentioned on my debugging page on my website, he will be able to "probe" through parts of the circuit and follow the signal without having to desolder or anything. I think it's a bad solder joint or a problem with the 1st Mini-Booster since he gets scratchy sound from the trimmers but no signal at all. This implies that the booster is boosting the trim "scratchiness" but no input signal.... Aron

 

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