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Argh...This is nuts...BSIAB II

Started by modsquad, August 20, 2006, 08:56:21 PM

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modsquad

August 20, 2006, 08:56:21 PM
Okay since I got the Duende Boost working, I moved on to the BSIAB II.   Of course the voltages are not correct but I will post those farther down.  I was testing the 1M resistors and noticed that two of them test 500 ohm.  Is it possible that they are bad or mislabeled.  I am assuming that they probably are.  I tested them without the battery connected to the circuit using a DMM.

Here are the voltages:

Q1:

D  5.16
S .55
G .0

Q2:

D  8.72
S  5.16
G  2.94

Q3:

D  4.45
S  .09
G  .0

Q4:

D  8.72
S  4.45
G  2.97

Q5:

D  .91
S  .82
G  0

Is it always like this when you finish the wiring or does it ever work the first time?  :icon_evil:

"Chuck Norris sleeps with a night light, not because he is afraid of the dark but because the dark is afraid of him"

modsquad

#1
August 20, 2006, 09:17:15 PM
One other piece of information I am using 2N5458 instead of 2N5457's. 
"Chuck Norris sleeps with a night light, not because he is afraid of the dark but because the dark is afraid of him"

ke4unr

#2
August 21, 2006, 03:32:20 PM
I've built the BSIAB II with success. I'll try to help, but don't count me as an expert at this.

Is it doing anything, or just not working at all? Do you get a signal through when in bypass?

The voltage readings at Q5 look a bit suspect to me (?). I'd double check the polarity of C9 and C11. What happens when you adjust the trim pot (R16)?

I just realized you didn't give the voltage reading of your battery. Make sure you have a good one - it can happen!

I don't believe the 2N5458's will cause you any problems. They might affect the overall tone.

Measuring resistors in the circuit will not always give you accurate results. It's unlikely, but the two you mentioned could be bad. You'll probably need to pull them out to check them. But, I don't believe that would keep the circuit from working (giving you something).

I've found that an audio probe can be one very helpful item for debugging circuits. They're so easy to rig up and use. I now keep a Smokey Amp on my desk so I don't have to keep dragging everything over to my other amps.

Of course, double check everything - solder joints, solder bridges (if any), wiring, etc.

Let us know.

Ray K.

modsquad

#3
August 21, 2006, 03:37:48 PM
Battery is at 8.73v.  On bypass I am getting sound of the guitar.  In fact on bypass it sounds like tone and volume are normal.  When switched on I get a cool blue LED and nothing else.  I am in the process of checking all the components and solder joints look okay.  I will check those caps and maybe swap them out. 
"Chuck Norris sleeps with a night light, not because he is afraid of the dark but because the dark is afraid of him"

DuncanM

#4
August 21, 2006, 07:03:43 PM
Strange that Q2 and Q4 gates aren't at half supply voltage - 8.72 / 2...

Q5 Drain is way too low - have you tweaked the trim pot?
If so, what happens?

Check that the FETS are the right way round or the right pinout? (Hey, I've done it...)

modsquad

#5
August 22, 2006, 10:30:40 AM
The FETs are correct.  I adjusted the trim pot and Q5 Drain is at 4.89.  I have started to look at the circuit to the gates on Q2 and Q4.  Any other ideas?

Thx

Stan
"Chuck Norris sleeps with a night light, not because he is afraid of the dark but because the dark is afraid of him"

jimbob

#6
August 22, 2006, 11:41:20 AM
I have this problem all the time after a completed build. Could be the way you wired it. Follow all your wires. You never know. Are your jacks new? I have reused old ones and found a bad stereo or mono jack bad or wired wrong. Lastly, Is everything grounded? I know these sound too simple but simple often does this to me in these simple ways.
"I think somebody should come up with a way to breed a very large shrimp. That way, you could ride him, then after you camped at night, you could eat him. How about it, science?"

modsquad

#7
August 22, 2006, 01:49:02 PM
Well now it seems that the only problem is that the volume of the pedal is extremely low.  I can just barely hear the signal.  It sounds good but I mean you have to crank the amp to hear it at all.
"Chuck Norris sleeps with a night light, not because he is afraid of the dark but because the dark is afraid of him"

Stephen

#8
August 22, 2006, 02:08:56 PM
Thats a typical cold solder joint!!!    Man BEEN THERE
:icon_rolleyes:

ke4unr

#9
August 22, 2006, 04:52:09 PM
Quote from: Stephen on August 22, 2006, 02:08:56 PM
Thats a typical cold solder joint!!!    Man BEEN THERE
I would agree. Just touch up each one. You can't always tell by looking and it won't take long to do.

Since you are now getting some sound out of it, you are SO close!

Ray K.

modsquad

#10
August 22, 2006, 08:45:24 PM
Okay so two things I figured out:

1.  Carefully go over the layout and compare the components.  I found I left 2 resistors off by accident.  Do...nk  :icon_redface:

2.  When you test it make sure have grounded the circuit to something.  I accidently touched one of the pots and the sound went way up.:  :icon_rolleyes:

I am in the process of tweaking and painting my box.  I will post when I get done.

Thanks all for the help, I learned alot about FETs and troubleshooting.

Stan
"Chuck Norris sleeps with a night light, not because he is afraid of the dark but because the dark is afraid of him"

ke4unr

#11
August 23, 2006, 12:56:36 PM
Way to go, Stan!

I'm happy for you. Do report back when you've got it completed and have a few hours of play time with it. Let us know how you like it.

Ray K.
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