BB Preamp troubleshooting

[Belanger]

Ok so this is where I'm at.  I have a bypass signal but zero output noise at all and I have the LED. No mods have been done but I've had to make do with some parts.  The 1uf polarized is a 1uf wima cap on mine  10uf electrocylic is a 10uf BP MUSE cap on mine. I've also used bc109b trannies and also have a 250k audio pot with a 270k (I think or a value close to that) resistor across Lug 1-3. I'll re check the resistor value  I'm a newbie lol. I have lots of linear pots as well but all much higher and lower values. Every other pot is correct value

Ok the JRC read pin1 4.81 pin 2 5.36 pin 3 4.69 pin 4 0 pin 5 9.72 pin 6 4.80 pin 7 4.81 pin 8 4.80

Tl072 in the same order 4.82,4.83,4.80,0,9.72,9.79,4.84,4.80

Transistor 1 E3.47 B 2.91. C9.72

Trannie 2 E3.56 B4.80-9 ( the difference was caused by a unsteady hand I'm sure) C3.58

As for the diodes D1 4.38/5.36
D2 4.38/5.36
D3 9.7/0.0


Any help is greatly appreciated
I'm very new at this. I think it's a ground/wiring problem but I could be way off

[Belanger]

Ive also checked the bipolar caps and there good

[287m]

is better when you show gut shot
and yes, something wrong in pin 8 = 4.80
are you sure is right pinout?

see below

[Belanger]

Shoot I put the entire 5,6,7,8 pins in the wrong order.  So what I said was pin 8 is pin 5 and so on.   :icon_redface:be I have a feeling the problem lies in my wiring, but I don't know enough to make a educated guess. I really appreciate the help because learning this troubleshooting process is essential for me

[Kipper4]

If it's built on vero. The layout you used might be helpful to any potential help you might get.

Have you got an audio probe?
Here's a thread or two that might help you with that

http://www.diystompboxes.com/smfforum/index.php?topic=112141.msg1033891#msg1033891

http://www.diystompboxes.com/pedals/debug.html

[Belanger]

Thanks for that link I appreciate it.  I've seen the audio probes being used in a few other troubleshooting videos in EE videos and really wanted to build my own. Also here's the pic of the vero layout. It was verified as well

[duck_arse]

your TL072 pin 7 should be about half supply volts. see why it is so high, bad connection somewhere, perhaps shorting to pin 8. power off, pull the IC's out the sockets, check the resistance between pins 7+8 on that IC socket.

[Belanger]

How do I check the resistance between be 7/8. I'm trying to find articles online and I can only find measuring the output impedance and im not fully grasping it and I'm not sure if that's even what your recommending.  A lot to learn for sure when you first start but honestly I find it fascinating. Not to mention some of you guys really know your stuff which gives me a lot of hope for the future

[Kipper4]

To check resistance between the pins as Duck says. Power off. Remove the chip.
Set the digital multimeter to resistance (ohms)setting.
One probe on pin 7
One probe on pin 8
Read the resistance and report back.

[Belanger]

Wow sorry I was complicating things. Also while I was lookin at my circuit I noticed a resistor out of place and 2 missing caps. I've put everything as supposed to be and triple checked.  Now my reading on pin 7 has dropped to 4.8 but pin 8 is still the same. 

Also for the resistance I put it on 2m setting and when I touched the probes to it, it just kept climbing and climbing until my meter couldn't read it

[Belanger]

Also I have a output now when I strum hard but it's still not working.

[antonis]

Also for the resistance I put it on 2m setting and when I touched the probes to it, it just kept climbing and climbing until my meter couldn't read it

to
I presume that you've forgot the cut under C7 4n7 and/or the jumper fron pin 8 to +9V shouldn't be in contact to pin 1 ..

[Belanger]

Just got this message now so I'm going to check that out and get back to you. Hopefully your correct which I'm sure you are Lol

Also for the resistance I put it on 2m setting and when I touched the probes to it, it just kept climbing and climbing until my meter couldn't read it

to
I presume that you've forgot the cut under C7 4n7 and/or the jumper fron pin 8 to +9V shouldn't be in contact to pin 1 ..

[Belanger]

Unfortunately it's not either of those things