General noobie questions :wiring, trimpot adjustment on a BASSMAN JFET PREAMP

[maunez16]

Hey guys hope ure fine could you help me with a little bit newbie question?
I took this schem from my very first look at this forum https://dl.dropboxusercontent.com/u/7464107/bassmanlayout.pdf
Its already soldered, and its not working (as i spected) so im now debugging it (im learning how to). and checking what is the schem, i dunno how to connect the trimpot tips (1 2 3), i bought a couple side trimpots, both have 8 turns by now, should i open them more to get current through?,
Also i would like to know how to correctly soldier potentiometer because i soldier them by the wholes : https://www.google.com.mx/search?q=potentiometer&tbm=isch&imgil=9FvX-pNm2ZRoUM%253A%253BW_rCecPvtsTtqM%253Bhttps%25253A%25252F%25252Fwww.tubesandmore.com%25252Fproducts%25252FR-V1MA-M&source=iu&pf=m&fir=9FvX-pNm2ZRoUM%253A%252CW_rCecPvtsTtqM%252C_&usg=__7yyd_Tt4EqIMyZU0AepY09aUSns%3D&biw=1280&bih=611&ved=0ahUKEwils__DiczLAhXjtoMKHaPgCdYQyjcIMg&ei=PevsVuWgMePtjgSjwaewDQ#imgrc=Gk_01O9K-Jn4SM%3A

and the last; can i join 4 diferent wires in a unique big soldier point? how close do they gonna be when soldered? cuz i got a lot of stuff just soldered like that, so that would be a cool point on where to start debugging, since i bought my first multimeter today i really dunno how to use it properly in terms of debugging a circuit.
Im begging for your help bros.., hope u have a nice weekend thanks for reading the whole stuff!!

[lukeferg]

You probably want to start by reading the debugging sticky http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Without knowing much about the circuit your problem is more than likely solder bridges, probably really small one that you won't even see. Get a Stanley knife and run it around your joins to hopefully break anything that might be there.

The other possible problem is your transistor pinout, check  and recheck that you've put them in the right way.

You can solder multiple wires together in one big join, that's how we usually ground things in a star ground. If you've got them all over your board though that's probably going to cause problems due to the messiness of the build. More likely to have a stray bit of solder somewhere. The cleaner the build, the more likely it will work first time and the easier it is to debug.

You want to use your multimeter by attaching the black lead to ground and then probing the transistor legs one at a time with the red. Have the multimeter on 20v dc and you're good to go, check you battery too. I haven't used multi turn trimpots, mine are all one turn, but you want the leg of the trimpot going to the transistor to probably be at 4.5v.

Post your voltages and then hopefully we can help more.

[Kipper4]

I think the schematic is here

http://www.diystompboxes.com/smfforum/index.php?topic=101898.msg903594#msg903594

[Kipper4]

Welcome to the forum.
The link you posted is for a layout not a schematic.
A schematic and accompanying notes is always useful.
Maybe you should post a picture of your board.
I'm unclear as to what trimmers you are using, since you say you did eight turns.
In the layout link you posted. You are looking at the back (bottom) of the pots not the shaft side (top) if that helps with your off board wiring.

[smallbearelec]

Hi--

This is not an ideal project for a complete newbie, as it has three stages; too many components = too many opportunities for small mistakes, and any one will make the thing not work. You used 10-turn trimpots (maybe because that was all you could find?), so possibly you had to change the layout slightly to use them and made a mistake there...hard to say. If you want to try debugging your existing build, make a clean copy of the schematic, set your meter to test continuity, and test to see that every connection on the board matches what is in the schem.

I did a build of this kind, called the Bare Ass Boost, and a breadboard layout:

http://diy.smallbearelec.com/HowTos/BreadboardBareAss/BreadboardBareAss.htm

The article begins with a discussion of how a JFET actually works, and the measurements shown might help you understand what is going on. Figure 31 and 32 show two stages, and the picture might help you with the potentiometer wiring. "CW" = "clockwise" and "CCW" = "Counter-clockwise".

If you don't have a breadboard yet, do invest in one. If you don't use it now, you will later.

[maunez16]

Thanks a lot everybody,you gave me some paths to follow:
I was already looking at the debugging page (the GEO and arons one), when i was reading your answers at my job i noticed i was wiring the pots wrong, so rewired everything and re-solder grounds

UPDATE:::
This may be the thing but theres something else i think its even more important, (i noticed while using multimeter, testing transistors (both work, i thought they would be burned):
I was checking voltage and it happens that it doesnt gets divided, and this happens at both resistors, it shows 9v at multi)
the trimpots i bough are these ones http://mexico.newark.com/productimages/standard/en_US/4415321.jpg (3006 104)
I conected the 9v input through the 3rd pin (which has a solder point with 2 wires, one at the 1st tip and another at the 3rd tip of the second resistor) and leave the 2nd to the transistor, but maybe thats how my question should be started.
:::: THERES ANOTHER IMPORTANT THING HERE:::: i didnt solder any tone switch at all, just a 2.2 cap with its respective resistor)
anyways ill keep tryinghard, i knew this wasnt gonna be easy or anything for begginers but hey, if i make it work i wont be as newbie as i was


NOTE: Im trying to upload my project image though arons account as it says here but somehow it loads and then it doesnt give me any link

[MaxPower]

Buenos dias señor.  A bit difficult to figure out which resistors you are talking about without referring to a schematic. Also hard to tell how you measured the voltages (on which side of the resistors etc.).

If all else fails, you can upload the pictures elsewhere and post the links here.

[J0K3RX]

This project is not too bad for a greenhorn in my opinion... Not the easiest but not bad.

I would recommend that you start with this and get it working, learn how it works etc.. This will lead you right into the F2B and a lot of other designs.
http://www.runoffgroove.com/fetzervalve.html

And this one that smallbearelec posted above is absolutely Excellent! This is a "Must Read!"
http://diy.smallbearelec.com/HowTos/BreadboardBareAss/BreadboardBareAss.htm


You need to learn how to crawl before you walk, you need to learn how to walk before you run... either way, plan on falling down and busting your ass a few times... 

[maunez16]

Buenos días, hermano, gracias por contestar.
http://es.tinypic.com/r/s3zres/9
http://es.tinypic.com/r/311rkn6/9
Here are some pics.
Theres an important thing: theres everything well grounded, but pots give no voltage signal, the voltage keeps at the caps;
from which parts should i take a voltage measure to tell you?
thx

[MaxPower]

Ay caramba. My poor internet connection prevents me from seeing your pics. Anyway, no dc voltages at the tone pots might be okay because of the capacitors. Check the dc voltages at each pin of both JFETs.

If you can plug your guitar in to the circuit, test for an ac voltage at the pots when you strum the strings. Might as well test for an ac signal at the output while you are at it. And before and after the first JFET as well. Try and find where the ac signal stops. That might help find where in the circuit the problem is.