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another Easyvibe debug!

Started by DFG, June 16, 2014, 11:45:16 AM

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DFG

June 16, 2014, 11:45:16 AM Last Edit: June 17, 2014, 01:00:16 AM by DFG
Hey guys!
I've been building stuff for years, but always easy projects. Recently I've built some modulation effects... but this one is kinda tricky for me.
I just finished the Easyvibe (GEOFEX pcb) yesterday and did a hell lot of testing today. I cannot figure out what's wrong with the circuit.
The voltages seem to be fine and all LEDs are on. The thing is they don't pulsate.
Here's the voltage readings with bith pots cranked
U1:
 1: 3.9
 2: 3.9
 3: 1.9
 4: 0
 5: 3.9
 6: 3.9
 7: 3.9
 8: 9v

U2:
 1: 3.4-3.9
 2: 3.9
 3: 3.9
 4: 0
 5: 3.9
 6: 3.9
 7: 3.9
 8: 9v

U3:
 1: 3.9
 2: 3.9
 3: 3.9
 4: 0
 5: 3.9
 6: 3.9
 7: 3.9
 8: 9v

U4:
 1: 3.4-4.6
 2: 3.9
 3: 3.5-4
 4: 0
 5: 3.9
 6: 3.9
 7: 3.9
 8: 9v
even with depth turned up and rate at minimum the supply voltage for the couplers pulses between 3.85 and 3.91. I think this is not enough for making the LEDS blink.
I've also tried tl072 - no improvement.
I think this is my first post here, hope you guys don't mind a newbie asking for help...

Thank you in advance!!  :)
best,
Gee
In previous armies, soldiers used their time to clean their weapons and stock up on ammunition. Our weapons are words, and we may need our arsenal at any moment.

duck_arse

#1
June 16, 2014, 11:58:04 AM
hello and welcome, dfg.

is your U4 pin 8 really 0V, or is that a mispront?

I can't find a circuit w/ part numbers, can you post or link to?
You hold the small basket while I strain the gnat.

DFG

#2
June 17, 2014, 01:07:11 AM
hello!
first of all thanks for your fast reply!

well, this is definitely a typo. It has 9v on the power supply pin.
I used this pcb layout: (http://www.geofex.com/PCB_layouts/Layouts/easyvibe.pdf) and this is the schematic with some minor differences as far as I can tell: (http://www.hollis.co.uk/john/easyvibe.jpg)
I also wanted to mention that I used TL062.

thanks,
G

In previous armies, soldiers used their time to clean their weapons and stock up on ammunition. Our weapons are words, and we may need our arsenal at any moment.

DFG

#3
June 17, 2014, 07:11:03 AM
well this is kinda awkward. I fixed the problem and it was a simple short at one of the traces that was too small to see but i scraped it away and the circuit works perfect! awesome sound, but that's no secret. I'll be modding it now.

thanks for trying to help me, duck! :)
In previous armies, soldiers used their time to clean their weapons and stock up on ammunition. Our weapons are words, and we may need our arsenal at any moment.

GibsonGM

#4
June 17, 2014, 08:59:24 AM
Quote from: DFG on June 17, 2014, 07:11:03 AM
well this is kinda awkward. I fixed the problem and it was a simple short at one of the traces that was too small to see but i scraped it away and the circuit works perfect! awesome sound, but that's no secret. I'll be modding it now.

thanks for trying to help me, duck! :)

Not awkward, DFG - totally typical, ha ha!  We all do that, even when we SWEAR we've looked 20 times....easiest sort of mistake to make.  Glad you got it going!   :)
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duck_arse

#5
June 17, 2014, 10:37:11 AM
yeah, me too, cause I was already outta ideas.
You hold the small basket while I strain the gnat.
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