Need Help with Delay Pedal Problems

[ReedK]

Hey guys! I'm new here and recently have got interested in building my own guitar pedals so I ordered a diy delay kit on amazon. I'm new to pedal building but was a mobile electronic installed for 10 years so I can use a meter.
Anyways the pedal comes with a very basic one page electronic layout and I'm afraid I have done something fundamentally wrong with the box components wiring as I had to make it up. The led turns on and signal comes through with the switch on and off, however there is no delay effect and the pots don't change the sound in any way.
Can anyone give me a place to start troubleshooting? I checked all the resistance values and retouched every solder joint, not sure where to go from here.
Another member built this pedal in January (PRR?) and figured out it was the Rebote 2.5 circuit.


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[GibsonGM]

Are you sure the battery is good?  Just checking! 

Got a pic of the back (solder) side, too?   

You'll get it eventually, hang in there...and welcome to the forum!! 

[ReedK]

Are you sure the battery is good?  Just checking! 

Got a pic of the back (solder) side, too?   

You'll get it eventually, hang in there...and welcome to the forum!! 

Thank you, I see the stuff you guys do here and I am blown away so I have faith I can get it going eventually haha. I checked the battery and it's reading right at 9 volts. It's allowing signal to pass with the battery in but not with it out so something is working haha just no delay.


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[GibsonGM]

Ok Reed, gonna need some voltages here!  Look at this page:  http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Come back here and post your voltages, ok?  Something could be wrong with your chip.
Some resistor(s) could be put in the wrong place.
Double check that your "in" and "out" jacks ARE the in and out jacks, that both sleeves are grounded. 
Be sure both chips are soundly in their sockets (you didn't solder with them IN, did you?)

I think voltages from IC pins will tell a lot.  Careful not to short pins together when measuring. 
Measure with batt in, and a plug in the input jack. 

[anotherjim]

Have you fitted the DC power jack to the pcb? It's missing in the last photo.
Without that, the battery + won't connect to the circuit as it relies on a switch in the jack to take over the +9v feed path when no power plug is inserted.

[ReedK]

Ok I can do that for sure, how should I list the voltages? The top left pin is 1 then go down ward? I've got the 9v plug wires up now Anotherjim, that was a preboxed picture and it mounted from the outside which was inconvenient. Thank you so much for the help guys!


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[ReedK]

And I double checked the jacks and have the correct one for input with grounded sleeves. I have removed the chips and reset them several times so I know they are in firmly. I ordered 2 new chips just in case and if I don't need them I will just build a Rebote 2.5 after this


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[anotherjim]

Downward from pin1 and then continue around anti-clockwise. Highest numbered pin is always opposite pin1.

[ReedK]

Downward from pin1 and then continue around anti-clockwise. Highest numbered pin is always opposite pin1.

Awesome thank you, here they are for the PT2399 chip:
1: 5.0
2: 2.51
3:0
4:0
5: 3.21
6: 2.51
7: 0.664
8:0.688
9: 2.514
10: 2.512
11: 2.512
12: 2.516
13: 2.512
14: 2.506
15: 2.512
16: 2.512


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[slashandburn]

It could be my eyes, or the lighting in the photo, but it looks almost as if one of your through hole solder joints is naked.     On the voltage regulator? (78L05). Right in the middle of the board.

I'm likely wrong. Might be worth a look though. Photo's can be deceiving but that joint looks strange on the photo.

[ReedK]

It could be my eyes, or the lighting in the photo, but it looks almost as if one of your through hole solder joints is naked.     On the voltage regulator? (78L05). Right in the middle of the board.

I'm likely wrong. Might be worth a look though. Photo's can be deceiving but that joint looks strange on the photo.

Oh wow yeah it may have been, I went back over it after this picture and resoldered everything and just looked and it's ok but it does look bare there thanks for checking!


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[ReedK]

Sooooo I swapped a 47 ohm resistor with a 47,000 ohm... and learned my first extremely valuable lesson about double checking component values! Thank you guys for the help!!!


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[bluebunny]

Learning by mistakes - it's the only way.      Good spot!

[anotherjim]

Cool. Just to finish, the PT2399 voltages look ok

[ReedK]

Learning by mistakes - it's the only way.      Good spot!

For sure! I'm honestly happy it didn't work the first time as I think I learned a lot more going through the whole circuit troubleshooting. I'm really excited about pedal building and this forum, thanks again!


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[ReedK]

Cool. Just to finish, the PT2399 voltages look ok

Awesome! What are you looking for to verify voltages at the chip out of curiosity?


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[bluebunny]

Without knowing toooo much about the chip, you know that pin 1 is your power supply (5V) and pins 3 and 4 are ground (0V).  Everything down the right-hand side (9-16) is audio ins and outs.  Since audio needs a midpoint to swing about (audio is AC), and you have a 5V power supply, then this midpoint is 2.5V - which is pretty much what you measured.  And this is what pin 2 - V_REF - is all about too.  Pins 5-8 are a little more esoteric and would need closer inspection of the datasheet and knowledge of the chip, but what you posted is typical (use "Search" to see other examples).

[ReedK]

Without knowing toooo much about the chip, you know that pin 1 is your power supply (5V) and pins 3 and 4 are ground (0V).  Everything down the right-hand side (9-16) is audio ins and outs.  Since audio needs a midpoint to swing about (audio is AC), and you have a 5V power supply, then this midpoint is 2.5V - which is pretty much what you measured.  And this is what pin 2 - V_REF - is all about too.  Pins 5-8 are a little more esoteric and would need closer inspection of the datasheet and knowledge of the chip, but what you posted is typical (use "Search" to see other examples).

Awesome that helps a lot thank you!


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[GibsonGM]

I wanted to know if it had power, and if there was power where there should not be (ground).  Other than that I dont know much about PT2399.

Yup, suspected a component mis-placed. Happens a lot.  I avoid those damn blue resistors like the PLAGUE for that reason.   It may just be me, but I find the tan ones SO much better to read! Can't choose what comes in a kit, tho.     I'm happy the lower resistance didn't cause you any apparent trouble before switching it out!

Glad it worked out!!  On to the next one - gotta feed your new addiction! 

[ReedK]

I wanted to know if it had power, and if there was power where there should not be (ground).  Other than that I dont know much about PT2399.

Yup, suspected a component mis-placed. Happens a lot.  I avoid those damn blue resistors like the PLAGUE for that reason.   It may just be me, but I find the tan ones SO much better to read! Can't choose what comes in a kit, tho.     I'm happy the lower resistance didn't cause you any apparent trouble before switching it out!

Glad it worked out!!  On to the next one - gotta feed your new addiction! 

Awe perfect yeah that will help when I inevitably run into a problem again. And I just ordered a board from tonepad of the same circuit so I can build it with better parts and see if there's a difference! This one was really for practice the quality of the box, pots etc. is not very good to say the least haha.


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