I built this chorus to spec and the pt2399 gets burning hot and sound dies out and it never choruses.
(https://i.postimg.cc/47gTyRYn/Screenshot-20200904-161636-Gallery.jpg) (https://postimg.cc/47gTyRYn)
(https://i.postimg.cc/ZBxzysNH/20200904-164252.jpg) (https://postimg.cc/ZBxzysNH)
(https://i.postimg.cc/V54cfTmL/20200904-164259.jpg) (https://postimg.cc/V54cfTmL)
(https://i.postimg.cc/qz5Vn3NP/20200904-164316.jpg) (https://postimg.cc/qz5Vn3NP)
there is a tiny spot of silver on top of your voltage regulator. is that solder splash, or some of the precious bodily fluids of the reg excaping?
voltages. remove the pt2399 from its socket and measure/post the voltages on the socket pins. then reinsert IC and remeasure/post voltages.
Out voltages 1=4.98 2=0.9 but erratic 3 -16 were all zero
In voltages 1=4.98 2=2.43 3=0 4=0 5=4.98 6=0.4 7=0 8=0 9-16 all 2.44
I tried new chip sound passes doesnt chorus then slowly dies out
Quote from: Unclereaper on September 05, 2020, 01:39:19 PM
Out voltages 1=4.98 2=0.9 but erratic 3 -16 were all zero
In voltages 1=4.98 2=2.43 3=0 4=0 5=4.98 6=0.4 7=0 8=0 9-16 all 2.44
I tried new chip sound passes doesnt chorus then slowly dies out
I hear you... It took me 4 builds to get this pedal to work! First of all, PT2399 are notoriously finicky. Try grounding it by placing it on a copper board (all pins touching the copper). Also, I ran into counterfit PT2399 issues, so a reputable source is important.
I think it's locking up. Pin5 should read about 2.5v when the delay chip clock is running.
Some PT2399 don't like the fast clock overdrive that Q2 applies.
Try lifting out one leg of R8 which will isolate Q2. If all else is good, you should have some effect going although not the best chorus sound possible.
No sound at all
Schematic?
Only one I've found is for an earlier build
(https://i.postimg.cc/F1cw0ZDG/Screenshot-20200905-184036-Chrome.jpg) (https://postimg.cc/F1cw0ZDG)
Quote from: jfrabat on September 05, 2020, 02:34:32 PM
It took me 4 builds to get this pedal to work!
It does sort of feel like we've known you your whole life and watched you grow up building that circuit. :icon_lol:
Quote from: EBK on September 05, 2020, 07:57:32 PM
Quote from: jfrabat on September 05, 2020, 02:34:32 PM
It took me 4 builds to get this pedal to work!
It does sort of feel like we've known you your whole life and watched you grow up building that circuit. :icon_lol:
No comment... ;D ;D ;D
Quote from: Unclereaper on September 05, 2020, 01:39:19 PM
Out voltages 1=4.98 2=0.9 but erratic 3 -16 were all zero
In voltages 1=4.98 2=2.43 3=0 4=0 5=4.98 6=0.4 7=0 8=0 9-16 all 2.44
I tried new chip sound passes doesnt chorus then slowly dies out
Let's start at the beginning - get the power working. Without the PT2399 in there, you should have:
Pin 1 - 5V, from the regulator. 4.98 looks good to me
Pin 2 - 2.5V reference voltage for the internals. 0.9V is wrong, and suggests to me that the grounding isn't good.
Pin 3 - Ground
Pin 4 - Ground
With the power turned off, you could do a continuity check between your ground points, especially those pins 3 and 4.
Once the power is good, then we can fairly safely put the chip in and see what happens and what voltages we get.
HTH,
Tom
chip-out pin 2 volts should be indeterminate - the pt internals do the dividing. pin 2 chip-in volts at 2V43 looks ok to me.
I think Ben Lyman established that the cap from the LFO to the depth pot is backwards [if polarised] if (+) is towards pot - but that wouldn't kill the effect.
Audio (clean/no effect) should get thru no matter what the PT2399 is doing.
If it starts with sound but it fades out, then the input amplifier could be drifting out of bias. There should be 5v on IC1 pin pin3 (coming from 330k R7) and the amp should copy that voltage to its pin1. Check for shorts/track cuts around there.
Quote from: duck_arse on September 06, 2020, 10:34:17 AM
chip-out pin 2 volts should be indeterminate - the pt internals do the dividing. pin 2 chip-in volts at 2V43 looks ok to me.
Ack, of course! Sorry! Duck is right. I'm an idiot!
Still, I stand by the rest of it - Check the power and grounds first, and then we move onto the other stuff!
Ok I'll try that and which one of you is Ben Lyman because I did business with you and u got me started on pedal building.
Ic1 4.8. 2.9 3.5 0.02 2.1. 2.4. 2.2. 6.7. Ic1 pin 3-4 pass continuity
Quote from: Unclereaper on September 07, 2020, 01:13:48 PM
Ic1 4.8. 2.9 3.5 0.02 2.1. 2.4. 2.2. 6.7. Ic1 pin 3-4 pass continuity
If 3+4 have continuity, something weird is going on, because you've got different voltage readings for two pins which are supposed to be connected together. Can you check to see what's happening?
Quote from: Unclereaper on September 07, 2020, 12:57:41 PM...which one of you is Ben Lyman...
Looks like Ben has been away a few weeks.
https://www.diystompboxes.com/smfforum/index.php?action=profile;u=43807
Quote from: ElectricDruid on September 07, 2020, 02:42:12 PM
Quote from: Unclereaper on September 07, 2020, 01:13:48 PM
Ic1 4.8. 2.9 3.5 0.02 2.1. 2.4. 2.2. 6.7. Ic1 pin 3-4 pass continuity
If 3+4 have continuity, something weird is going on, because you've got different voltage readings for two pins which are supposed to be connected together. Can you check to see what's happening?
I think IC1 is the dual opamp Tom.
Pin8 6.7v shows a weak battery.
I wonder if the power supply is just fading under load?
IC1 pin3 should read closer to the 5v output from Q2 which is also pin1 of the PT2399. Pin1 should have 5v.
Is the PT2399 still out of the board?
Its was in when I tested it all
It was in when I tested it all
I would test without the PT2399. There is a path for clean audio through 1C1 so you should prove you can get it and prove the 5v regulator is giving 5v to IC1 via its pin3 as explained earlier.
Quote from: anotherjim on September 07, 2020, 05:22:04 PM
Quote from: ElectricDruid on September 07, 2020, 02:42:12 PM
Quote from: Unclereaper on September 07, 2020, 01:13:48 PM
Ic1 4.8. 2.9 3.5 0.02 2.1. 2.4. 2.2. 6.7. Ic1 pin 3-4 pass continuity
If 3+4 have continuity, something weird is going on, because you've got different voltage readings for two pins which are supposed to be connected together. Can you check to see what's happening?
I think IC1 is the dual opamp Tom.
Gah, I'm going to stay out of this from now on! I seem to keep getting the stick by the sticky end. ;)
Carry on, everyone. Good luck!
I have the very same problem - sound is passing, but no chorus.
Measured everything, but voltages on PT2399 pins 5&6 are suspicious:
1 5.0
2 2.5
3 0.0
4 0.0
5 2.1
6 0.46
7 1.03
8 1.03
all the rest sit at 2.5V
Schematic is here:
(https://i.postimg.cc/7Gm3wT2n/little-angel-sch.jpg) (https://postimg.cc/7Gm3wT2n)
Standard advice.
Don't attempt to start testing with the go-faster low resistor (your R23). If it won't run without that, suspect a latch-up of the PT2399. With power off, short all its pins out with some metal foil for 10 seconds or so - this to discharge any static build-up in the chip.
Test again in your vibe mode, starting with the minimum LFO depth. If hear signal, increase LFO until you hear pitch warble.
In my experience, the chip doesn't much like running above 21Mhz or so. Can you measure the frequency on pin 5?
Quote from: anotherjim on January 30, 2021, 04:52:58 PM
Standard advice.
Don't attempt to start testing with the go-faster low resistor (your R23). If it won't run without that, suspect a latch-up of the PT2399. With power off, short all its pins out with some metal foil for 10 seconds or so - this to discharge any static build-up in the chip.
Test again in your vibe mode, starting with the minimum LFO depth. If hear signal, increase LFO until you hear pitch warble.
In my experience, the chip doesn't much like running above 21Mhz or so. Can you measure the frequency on pin 5?
I have removed R23 and tried to sweep LFO depth in "Vibrato" mode (so no original signal), but it's doing nothing. It just seems that the attack of the note is lost, but no delay at all. This is what I have at pin 5 of PT2399 - don't mind that reflection from my lamp, it's almost good square signal. Div size is .1us, so I have nine periods at 8 divs. It is 11.25MHz, right? It seems that LFO's not working. I don't see any voltage variation on pin 2.
This is what I have at pin 5:
(https://i.postimg.cc/WDgxVyZj/pin-5.jpg) (https://postimg.cc/WDgxVyZj)
Also, without R23, pin voltages are like this:
1 5.0
2 2.5
3 0.0
4 0.0
5 2.87
6 2.47
7 0.66
8 0.66
So there's a difference at pins 5, 7 and 8.
Also tried to use another op amp (TL 072 instead of RC 4558), but no difference at all.
I'd say the clock VCO is now working. However, the audio needs investigating. The attack only sound suggests heavy gating. This could be because it getting through via leakage/capacitive coupling.
Input audio heard at pin15 suggests the input opamp is good. Audio out at pin12 suggests the delay line is working.
I have damaged some PT2399's. Its opamps and clock worked. I put it down to excessive voltage swing applied to pin 2.
Others have fixed them by the discharge with foil trick.