Hello everybody...
I´m trying to debug my Double Flush build (current revision, etched) found in this link.
http://www.madbeanpedals.com/projects/DoubleFlush/docs/DoubleFlush.pdf
I have made the following substitutions because i could not source the original components.
IC3 - TL082/NE5532/LM1458/JRC4558 (TL062 listed).
IC2 - TL071 (LF351 listed).
R14 - 20k (18k listed).
R16 - 1M8 (2M2 listed).
R18 - 3M6 (3M3 listed).
LDR2 -Roll-your-Own Red diffused 5mm led and LDR (VTL5C1 listed).
The problem that i have is that the oscillator around IC3 doesn´t work, both status and LDR leds stays fixed.
I have audioprobed the circuit and the clean signal goes from the begining (R1-C1) to the end (R11) without problems.. but i get a clean signal only, The BAL, VOL and INT pots seem to work, because INT pot dimms both leds, VOL reacts normal and BAL goes from clean signal (JRC4558 side) to very weak signal (LF351 side).
I have also double checked component values, orientation and solder bridges/cold joints, etc.
Things that i have thinked going trough with the scheme.
- I measured 5.29 v between R22-R23, shouldn`t this be 1/2 VC? i´ve replaced both 100k resistors with new ones.
- I have 4.55v between R20-R21.
- The pulse pot doesn´t work (obviously).
- Pin 3 @ IC2 when measured turns off the leds and i have to reset PSU.
- I have soldered a 100k trimpot as a variable resistor between VC and GND and when turned manually, leds dimm and blink up again.
My DMM readings @ 9.02 VDC
IC1 (JRC4558)
1.- 4.30.
2.- 4.26.
3.- 3.81 (Voltage Drops to 3.38 when measured).
4.- 0.
5.- 3.78 (Voltage Drops to 3.40 when measured).
6.- 4.25.
7.- 4.32.
8.- 8.28.
IC2 (TL071)
1.- 0.11.
2.- 4.74.
3.- 1.32 (Voltage Drops to 1.27 when measured).
4.- 0.
5.- 0.11.
6.- 3.96.
7.- 8.31.
8.- 0.
IC3 (TL082)
1.- 3.70.
2.- 3.88.
3.- 4.01.
4.- 0.
5.- 4.00.
6.- 4.01.
7.- 3.95
8.- 8.29.
I will try to get a couple of TL062 next week because i am begining to think that this IC is vital for the circuit.
I will upload high res pics as soon as i can.
Thanks in advance for any tip you have if you see something that i missed.
Best regards.
Hernan.
Little update, i`ve triple checked and measured component values and tested tracks for solder bridges/cold joints, reflowed all the oscillator components, and took pictures.
(http://i1299.photobucket.com/albums/ag68/jorgedorio/P1000021_zpsb98c7389.jpg)
(http://i1299.photobucket.com/albums/ag68/jorgedorio/P1000022_zps0656bb28.jpg)
(http://i1299.photobucket.com/albums/ag68/jorgedorio/P1000023_zpsacb53d6f.jpg)
is that a roll your own vactrol? I recently had a trem, that would literally not work with any kind of vactrol, i put a vtl5c3, (or vtl5c4 maybe?) and boom, tremage straight away.. i'm not familiar with this circuit though. That is just my recent experience.
good luck
george
Quote from: hammerheadmusicman on March 29, 2013, 05:19:53 PM
is that a roll your own vactrol? I recently had a trem, that would literally not work with any kind of vactrol, i put a vtl5c3, (or vtl5c4 maybe?) and boom, tremage straight away.. i'm not familiar with this circuit though. That is just my recent experience.
good luck
george
Almost anything should trem in this design. I think the op's issue is that he's actually not getting oscillation on the op amp.
ah right, ok.. should've read better ;)
Hey guys, thanks for your feedback.
I am begining to think the same, it´s the op amp, i can´t understand why, but until i don´t test the circuit with a TL062 i can´t think of anything else.
I`ll have to wait until Wednesday to get a TL062 due to easter holidays in Argentina, then i´ll post my results.
Hernan.
The build PDF specs a LF351... are you not able to source this?
(Given how the go-to opamp is typically a TL0xx, there is presumably a reason for this part, I dunno...)
Check some of your solder joints, there's a few on the right (bottom side image) that look cold and/or dry. A little flux will help.
Good luck!