Thunderchief Debug

[mrpenguin354]

Hey everyone!

I put together a Thunderchief following the breadboard schematic from run off groove, but I'm having alittle bit of trouble getting it to work.

I went through the debugging steps (double checking the J201s are positioned right, checking voltages, and checking the grounds), but I still cannot get ANY of the J201s to drain.  Here's what I've found out so far:

Battery - 9.46v

- The left side of the board up to the (S)ink lead of the first J201 is underpowered (reading 8.61v instead of 9.46v)
- All the grounds are grounded correctly (0.00 ohms)
- The rest of the board is recieving the proper amount of power
- The switch is wired correctly because it works when the effect is switched off
- Turning the trimpots - NOTHING, no change at all in the voltages (which worries me)
- The left side of my DPDT switch reads at 8.61v

J201 voltages:
Q1:8.61(G); 9.46(S); 9.46 (D) 
Q2:8.26(G); 9.46(S); 9.46(D)
Q3:8.59(G); 9.46(S); 9.46(D)
Q4:9.26(G); 9.46(S); 9.46(D)

Hmm...that does not look good at all....

http://photobucket.com/albums/a3/mrpenguin354/Pedal are some pictures I took of the board.  I know my soldering and wiring job may seem a bit shoddy, but everything is reading at the right voltages (save what I listed above).  The copper wire running around the underside of the board is my "universal ground" (patent pending j/k ).  And there are notes on each picture explaining what goes where.

I appreciate any suggestions you guys have.  This is my first build so I'd like it to work (eventually).  Please let me know if you need specification on anything.

[RDV]

You need to make sure you wired your trimpots the right way. If you left the wiper pin open then they will do nothing.

RDV

[mrpenguin354]

I'm pretty sure the trim pots are wired right, I connected two of the wipers together (the two that line up with the ae cap.) and soldered them, but I will double check them in the morning.

Thanks!

[didier]

 

neat soldering job...

[petemoore]

  You need to make sure you wired your trimpots the right way. If you left the wiper pin open then they will do nothing.
   Could be just hooking a DMM lead to V+ on the battery clip, then poking the other one in the Drain socket lug, set to R Range, twist the pot and read the resistance between Drain and V+ ...what I try if adjusting the bias pot doesn't move the Drain Voltage around.

[RDV]

Neither of the two pins that are in line with the Fets are the wiper of the trimpots. The one off to it self in the middle is the wiper.

Or, if you wired the two outside lugs together and hooked the wiper to the v source then you've shorted the pot and it will do nothing.

READ THIS(and everything else there).

RDV

[mrpenguin354]

Just an update..

I wasn't able to do much today, but I'm glad everyone's trying to help me out, sometimes it's hard being a noob...

Anyways, I double checked all my soldering and groundings and they appear to be correct.  I'm assuming that if something shorted out or got fried that it would not let any voltage pass through.  Soldering wise, today I unsoldered the trim pot leads because the whole wiper thing has me confused.  I took a picture of my pots from the underneath and labeled the leads to the best of my ability.

RDV:  I read the secret life of pots page, but I didn't find anything particularly helpful besides how a pot works, though if that was your intent then I did learn something.



The blue line in the picture connects to the rest of the board.
The green line connects to the red line.
The red line connects to the AE cap and the 9v supply.

Did I do anything wrong?  Fry anything?  Should I do something?

[RDV]

RDV:  I read the secret life of pots page, but I didn't find anything particularly helpful besides how a pot works, though if that was your intent then I did learn something.

If you know how a pot works then you now know how to wire up a pot. If you have them wired correctly then you should be able change the voltage at your blue marks as you turn the trimpots. If not, they're still wired wrong.

RDV

[mutant_guitar]

have you checked your board to the schematic? ROG does not show every single ground connection on the layouts, you have to read the schematic to be able to wire everything. by the way it sounds, it really does seem like you just didn't connect your trimpots right. by the way, i just posted a sound clip today of my TC... 

[mrpenguin354]

have you checked your board to the schematic? ROG does not show every single ground connection on the layouts, you have to read the schematic to be able to wire everything. by the way it sounds, it really does seem like you just didn't connect your trimpots right. by the way, i just posted a sound clip today of my TC... 

Lucky!  Right now my rig is a modded tubescreamer through a distortion pedal (THUNDERCHIEF &*^#*@) to an old Ampeg power amp so I'm basically rigless save my little practice amp  .  BTW your clips sound awesome and I can't wait for the darn thing to work. Though I have to admit, when I saw Children of Sanchez I was expecting some sort of latin feel Children of Bodom. 

I'm praying its the trimpots.  I'll be trying them out ASAP but finals are next week and I've got a research paper due.   

Thanks again!