EHX Bassballs

[Zanius]

So, after this topic, here goes debugging :)

The problem is, as can be read in above topic, not only there's no sound from output, but when connected to speaker, there's not even a buzz when touched.

EHX Bassballs







Let me tell you that the 47K on output is replaced by a link for adding a volume pot (board output to 3, ground on 1, main output on 2). I tested with and without the pot.
Also, the double links are checked and working, and the two 22k resistors on the bottom rows are in place second row from bot, and not last row as they seem to be in the picture.

Now, voltages:
Input  8.70v

"While measuring
Switch on position 3
Trimmers both on middle"

Ic1 MC1458
1-4.34  
2-4.34  
3-3.47
4-0      
5-0
6-1.85
7-2.05
8-8.70

Ic2 MC4558
1-4.32  
2-4.34  
3-4.25  
4-0    
5-4.26
6-4.35
7-4.32
8-8.69

Q1 Bot left
C-0.01
B-0.48
E-0

Q2 Bot right
C-0.01
B-0.54
E-0

Q3 Mid right
C-8.70
B-1.68
E-7.11

I hope I don't forget something, feel free to ask anything because I'm really confused by this not working.
Thanks to anyone taking the time to examine this :)

[ξεναγος νεκροπολης]

hi giannis.
everything looks ok to me. i can't see anything wrong. i've checked your cuts-links-polarities. all in place. i suppose you've placed your transistors&ics in the right orientation.
i just can't see the wiring but there is nothing difficult in that.
check again for unwanted bridges. and be sure that your test box works fine.
i don't know man. i can't think of anything else.
hope you'll fix it.
 

[Zanius]

Thanks for checking savvas. Yeah, everything seems right to me too.
I will check again for shorts and if nothing happens, I will start replacing components. My mind is set that whatever is wrong is around the output area. Anyway, I'll let you know once I find it!

[induction]

Zanius wrote

Let me tell you that the 47K on output is replaced by a link for adding a volume pot (board output to 3, ground on 1, main output on 2). I tested with and without the pot.

The link is the problem. The link is grounding the output, just like you suspected. Remove it, and I bet the circuit fires right up. There could still be another problem that hasn't shown up yet, but the link is definitely preventing any output.

A little more detail:You didn't replace the 47k with a volume knob, you replaced it with a volume knob in parallel with a short to ground. Look at the schematic and mentally (or physically, if you want) draw in a volume knob on the output and replace that 47k pulldown with a jumper. You should be able to see that the output is now grounded.

[ξεναγος νεκροπολης]

that's right man!!!i was also confused about that but by misreading miro's comment at the main post i thought that would be ok. that link explains everything.
cut it!

[Zanius]

I can't believe that went past me...

Truth is that mirosol writes in the layout page "I would also snip the 47K resistor from the input". He doesn't say anothing about replacing it with a link. I just assumed that the resistor was to lower the output volume from the Ic.
And then I measured voltages and saw that pin 4 was ground, AND I had in mind that the output was grounded and still failed to connect the dots...

Thank you, I'm gonna give it a go later and let you know.

[Zanius]

And.. Yep! That did the trick.
Everything working right now.Vol, response and switch all in the game!

Thanx for the indication Induction!

------Debugged-------