Equinox: Easy PT2399 Reverb

[Yazoo]

I've built the Equinox over Christmas and had the same problem others reported. I'd get signal out but no reverb - so I tried dropping the voltage as suggested and swapped out the PT2399s. I just used a spare BAT42 diode I had and soldered it to the output  pin of the 78L05 which dropped the voltage to about 4.5 Volts. I still wasn't getting any reverb so I checked the signal path with my oscilloscope and it turned out I had a solder bridge which was shorting pins 15 and 16 of the first PT2399. Isn't is classic when you assume it is one thing and it turns out to be something else completely different! I always have to resist the temptation to start ripping the circuit apart.

Now it is working it is really good. Definitely worth the effort.

[cobexonly]

Hello, 

I love the sample sound for Equinox reverb, so i decided to build this one. And now I'm having a little trouble with my Equinox. Kindly check my work regarding the wiring and all. I used 3PDT for switch, BC337, 10uF NP and 8uF NP caps, TL072, 7805. I have bypass signal, and if I push the switch I just have the led ON but the sound same with bypass signal (No reverb sound At all), I try to rotate pots and trimpots but not effected the sound, I swapped for other PTs but nothing changed. I already measure voltages the op-amp and PT's.

Dual Opamp: Pin 8 and 4 = 8.57 V

PT2399: Pin 1 and 3 = 4.85 V

now i'm looking for ideas or suggestions for resolve my equinox problems

Here's some pict :
PCB Lane


FRONT View


Wiring View

[merlinb]

I have bypass signal, and if I push the switch I just have the led ON but the sound same with bypass signal (No reverb sound At all), I try to rotate pots and trimpots but not effected the sound, I swapped for other PTs but nothing changed.

I can't see anything in the photos yet... Try the screwdriver test I mentioned here:
http://www.diystompboxes.com/smfforum/index.php?topic=93421.msg808420#msg808420

[cobexonly]

Thanks for reply merlin   

I don't sure how the "reverberating pop in the speaker" sound like. So I make this video. check this out :

   I'm confused

[merlinb]

Thanks for reply merlin   
I don't sure how the "reverberating pop in the speaker" sound like. So I make this video. check this out :

You were touching pin 1. You must touch pin 16!

[cobexonly]

Thanks for reply merlin  
I don't sure how the "reverberating pop in the speaker" sound like. So I make this video. check this out :

You were touching pin 1. You must touch pin 16!

OMG, sorry I was careless.    

I just poke at pin 16 and the results are the same as when I poke Pin 1 on that video ....

[merlinb]

I just poke at pin 16 and the results are the same as when I poke Pin 1 on that video ....

That suggests some possible causes:

1: Faulty PT2399?
2: Incorrect pot wiring?
3: Signal from PT2399 is not reaching opamp- check for PCB problems and incorrect components in this path?

Could you post the voltages on all of the IC pins?

[cobexonly]

I just poke at pin 16 and the results are the same as when I poke Pin 1 on that video ....

That suggests some possible causes:

1: Faulty PT2399?
2: Incorrect pot wiring?
3: Signal from PT2399 is not reaching opamp- check for PCB problems and incorrect components in this path?

Could you post the voltages on all of the IC pins?

1. Maybe  ... I post the voltage first in the all IC
2. I've checked and no wrong pin
3. I've checked path of PCB, no broken or short. And there are some parts that I replace such as:

I put 27k resistor in R19, the original value should be 22K
I put 2.2nF capasitor in C5, the original value should be 10nF
I put 12nF capacitor in C8, the original value should be 10nF
I put 12nF capacitor in C11, the original value should be 10nF

Is it possible because of component substitution is causing the problem? 


Here is the voltage

IC 1 PT2399

1 = 4.84 V
2 = 2.43 V    
3 = 2.8 mV
4 = 27.g mV
5 = 2.78 V
6 = 2.42 V
7 = 0.7 V
8 = 0.7 V
9 = 2.4 V
10 = 2.4 V
11 = 2.43 V
12 = 2.43 V
13 = 2.43 V
14 = 2.5 V
15 = 2.5 V
16 = 2.5 V


IC 2 PT2399

1 = 4.8 V
2 = 2.4 V    
3 = 3.9 mV
4 = 35 mV
5 = 2.7 V
6 = 2.4 V
7 = 1.3 V
8 = 0.9 V
9 = 2.4 V
10 = 2.4 V
11 = 2.4 V
12 = 2.4 V
13 = 2.4 V
14 = 2.4 V
15 = 2.4 V
16 = 2.4 V


Op amp TL072

1 = 4.3 V
2 = 4.3 V    
3 = 3.9 V
4 = 2.5 mV
5 = 4.3 V
6 = 4.3 V
7 = 4.4 V
8 = 8.7 V

[merlinb]

Is it possible because of component substitution is causing the problem?  

Voltages all look OK.
Parts substitutions are not a problem (I think).

Take a piece of wire and jumper the two outer legs of the BC337; this will bypass the electronic switch. Any improvement?

(Actually you could remove the transistor from the socket and stuff the wire into the socket instead)

[cobexonly]

Is it possible because of component substitution is causing the problem?  

Voltages all look OK.
Parts substitutions are not a problem (I think).

Take a piece of wire and jumper the two outer legs of the BC337; this will bypass the electronic switch. Any improvement?

(Actually you could remove the transistor from the socket and stuff the wire into the socket instead)

I finally got my sound reverb  .... I am very pleased. thanks for helping me solve this problem merlin ... 

[merlinb]

I finally got my sound reverb  .... I am very pleased. thanks for helping me solve this problem merlin ... 

Great! But what was wrong with it

[cobexonly]

I finally got my sound reverb  .... I am very pleased. thanks for helping me solve this problem merlin ...  

Great! But what was wrong with it

This is a chronology :  

1. First I replace the resistor and capacitor that I replace before with the original value. --> Not produced good results
2. I replace 7805 with LM317 + couple resistor (make voltage drop to 4.2V). but still  no result, so I am replace back again using 7805.
3. I spray the PCB using contact cleaner and then brush it with a toothbrush. but not yet produced good results
4. I try to pull out the BC337 and then jumper using  wire. But it has not produced results. So I put BC337 back to the socket.
5. Then I'm take a part my rebote delay 2.5. I try PT2399 that installed in equinox to runing in Rebote delay (To make sure PT2399 in normal condition) finally running smoothly in rebote delay. I finally plug PT2399 back in the equinox and I get a hard oscilating in a few minutes and finally after it appeared the reverb sounding.
6. actually i also don't know what happened at my PT2399 ...  
7. The important thing is now running smoothly ... hehe ^ _ ^




I'm forgot to say : I replace TL072 with LM833  

[cobexonly]

after a one day my equinox  was running smoothly, now my equinox is getting error again.  
I make a videos to figure out the problem is and possibility to fix that's error ...

Note : "there is no part that was replaced / substitute, all in accordance with the recommended part"

Here's the video :

"Please excuse my poor/bad English"

[merlinb]

after a one day my equinox  was running smoothly, now my equinox is getting error again.  
I make a videos to figure out the problem is and possibility to fix that's error ...

The popping sounds like a broken wire or guitar cable. It also sounds like you have a troublesome PT2399 (or two). This might be because they have latched-up during a previous project, or because they are faulty. Some faulty PT2399s have been sold recently; they can oscillate. How many PT2399s do you have in your collection? When did you buy them?

[cobexonly]

after a one day my equinox  was running smoothly, now my equinox is getting error again.  
I make a videos to figure out the problem is and possibility to fix that's error ...

The popping sounds like a broken wire or guitar cable. It also sounds like you have a troublesome PT2399 (or two). This might be because they have latched-up during a previous project, or because they are faulty. Some faulty PT2399s have been sold recently; they can oscillate. How many PT2399s do you have in your collection? When did you buy them?

I have 5 PT2399's, I buy from local electronic store here. And now I put 2 new PT2399 at equinox, until now running smoothly ... Hopefully will always be stable ... 

[cobexonly]

Finally after a few days mess around with my equinox stability problem   . Today I find great solution, I have to do a little mod to my equinox, I need to jumper cables like the photo below :  

After I do that my equinox work very smoothly without any latching problems or something error else.


This is the video, I take with a cheap camera.
"Please ignore the knob label  "

[Mark Hammer]

Mine wasn't working.  Went over it with a magnifying glass looking for a bridge or crack.  Everything checked out AOK.  Tried sticking another diode in series with the 5v supply to drop things down a bit.  Didn't do it.  Then, going through this thread, I looked at the Russian site, and realized that there was supposed to be a switch.  For some reason, I thought the board represented the entire circuit and  I was all set to run the input and output pads to a stompswitch.  However, the Russian site drew my attention to the presence of a switch connected to the pads at the edge.  It should have been obvious to me, but somehow the schematic drawing threw me off.   So I wired up a switch and bingo-bango, I had reverb!

[merlinb]

Finally got round to re-etching my Equinox. Didn't come out too badly, though I still haven't quite got the hang of it, clearly!
I also made a couple of mods to reduce the bass; changed C33 to 15nF, and C13 to 100nF.

[sugonidamaso]

wow!great work merlin!i'm interested on how to etch in the box???designs?applications?sorry off topic.hope you don't mind.

[merlinb]

wow!great work merlin!i'm interested on how to etch in the box???

See Slade's thread about etching:
http://www.diystompboxes.com/smfforum/index.php?topic=80962.0