# Bypass works but mahayana does not turn on...



## Dirt_diggler (Sep 14, 2020)

Unfortunately I ran out of hook up wire so I had to use scraps of pieces I had. Apologies for the mess. I seem to have everything hooked up according to the generic wire diagram on the mahayana pdf. Another thing I was wondering is if It is ok to use a 3 prong dc jack if I do not plan to use a battery snap?

I'm curious if I hooked up the switch wrong.



https://imgur.com/a/RWZCOu3


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## music6000 (Sep 14, 2020)

Show a good picture of the other side of PCB, There is some excess solder around IN GND SW OUT connections.
Sometimes this forms a Blob on the underside & touches pad next to it.


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## Dirt_diggler (Sep 14, 2020)

music6000 said:


> Show a good picture of the other side of PCB, There is some excess solder around IN GND SW OUT connections.
> Sometimes this forms a Blob on the underside & touches pad next to it.



Doesn't seem like there is a short.  I've been poking and prodding while strumming in hopes of hearing something. I can hear a little static here and there depending where I touch. 



https://imgur.com/a/9SCKkGl


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## Danbieranowski (Sep 15, 2020)

Can you take a closer up picture of your DC Jack? Want to make sure that’s wired appropriately. It’s fine to even without a battery as long as it’s wired appropriately. Since you aren’t getting power let’s start there. Also make sure you’re using a center negative power supply.


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## music6000 (Sep 15, 2020)

Danbieranowski said:


> Can you take a closer up picture of your DC Jack? Want to make sure that’s wired appropriately. It’s fine to even without a battery as long as it’s wired appropriately. Since you aren’t getting power let’s start there. Also make sure you’re using a center negative power supply.


I blew the picture up, It appears he has tried battery terminal, now it's on the Power Supply terminal.
As you said, Does he have 9v center negative power supply.

I alo want a good picture of the soldered side of the PCB board or we are wasting time trying to guess.


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## Dirt_diggler (Sep 15, 2020)

I took three pics the best I could considering the pots are formed right on top. I may remove them today and test for continuity. I'm still learning how to read schematics so maybe a scratch build wasn't the best idea. I triple checked my resistors and caps and they are all the right value. As well as the diodes and transistors. My concern is the chip. Im not sure how to test the chip but when I poke with a tester sometimes I get a bright light and sometimes I get a dim light. 



https://imgur.com/a/jErDufC


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## Dirt_diggler (Sep 15, 2020)

Danbieranowski said:


> Can you take a closer up picture of your DC Jack? Want to make sure that’s wired appropriately. It’s fine to even without a battery as long as it’s wired appropriately. Since you aren’t getting power let’s start there. Also make sure you’re using a center negative power supply.




Here are a couple d the jack. The scratches are because I had to resize the hole and I suck with a drill. 


https://imgur.com/a/X1mZIKT


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## Dirt_diggler (Sep 15, 2020)

Do these three items need to be grounded? It seems as though they all show continuity with ground. 



https://imgur.com/a/NIjSUju


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## music6000 (Sep 15, 2020)

If the Footswitch is ON, Yes.


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## Barry (Sep 15, 2020)

Black wire from DC Jack looks pretty dry


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## music6000 (Sep 15, 2020)

Barry said:


> Black wire from DC Jack looks pretty dry


Yes, It needs a good jiggle and it might fall out!


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## Dirt_diggler (Sep 16, 2020)

music6000 said:


> Yes, It needs a good jiggle and it might fall out!



I resoldered that.


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## Dirt_diggler (Sep 16, 2020)

How do I check the integrity of my IC chip? I feel like there may be an issue with pin 3


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## music6000 (Sep 16, 2020)

What other Op Amps (Chip) do you have?


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## Dirt_diggler (Sep 16, 2020)

music6000 said:


> What other Op Amps (Chip) do you have?



It is a single ad712jnz with socket. 
Transistors are 2n7000


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## music6000 (Sep 16, 2020)

Dirt_diggler said:


> It is a single ad712jnz with socket.
> Transistors are 2n7000


I mean, do you have other Op Amps you can try ie JRC4558D, TL072


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## Dirt_diggler (Sep 16, 2020)

Oh. I have dozens of pedals. Maybe I can yank one and see. Thanks for the tips. Basically just make sure it's pdip8? I mean no other format should fit, right? I'll probabaly google each chip to make sure it is an op amp


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## music6000 (Sep 16, 2020)

Dual Op Amps, OPA2134 is closest to AD712,  Most common 4558, TL072 will also work!


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## Dirt_diggler (Sep 16, 2020)

music6000 said:


> Dual Op Amps, OPA2134 is closest to AD712,  Most common 4558, TL072 will also work!


Right in! I have 3 TL072 in a klon clone. I'll pop one in. Hopefully it doesn't fry the chip lol.


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## Dirt_diggler (Sep 16, 2020)

Last night I noticed that I get a very miniscule amount of volume. Like you have to really listen hard to hear it. All of the knobs work and change sound. When fiddling around I accidentally let the positive of the output jack touch the lugs of the voice knob and it kicked in full volume however I had super muffled bypass

Any idea what that means?


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## Dirt_diggler (Sep 14, 2020)

Unfortunately I ran out of hook up wire so I had to use scraps of pieces I had. Apologies for the mess. I seem to have everything hooked up according to the generic wire diagram on the mahayana pdf. Another thing I was wondering is if It is ok to use a 3 prong dc jack if I do not plan to use a battery snap?

I'm curious if I hooked up the switch wrong.



https://imgur.com/a/RWZCOu3


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## zgrav (Sep 16, 2020)

1.  does your LED turn on when you are not in bypass mode?
2.  please use your meter and give us the voltage readings for every pin on the IC and on the transistors.


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## Dirt_diggler (Sep 16, 2020)

zgrav said:


> 1.  does your LED turn on when you are not in bypass mode?
> 2.  please use your meter and give us the voltage readings for every pin on the IC and on the transistors.


My led does not turn in in bypass or engaged. I will report back with readings tonight.


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## Dirt_diggler (Sep 19, 2020)

So I dropped my pedal off with a repair guy last week. He called me today to tell me my wiring was 100% and that I had a bad chip. He gave me a tl072 and installed a new led because mine was not working. 

Haven't had a chance to listen to the pedal yet but I'm very excited. 

Has anyone here dealt with replacements from mouser? Are they fair?


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## music6000 (Sep 19, 2020)

music6000 said:


> I mean, do you have other Op Amps you can try ie JRC4558D, TL072


I did suggest that you try other Op Amps, That is why this Forum is here????


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## Dirt_diggler (Sep 19, 2020)

music6000 said:


> I did suggest that you try other Op Amps, That is why this Forum is here????


You did and I'm not taking that away from you. I even said I was going to pull one from a pedal and try it. However I ran out of time and had a short window to drop this off before I wouldn't be able to mess with it for a few days. He's a friend. It was beer money. Life happens. I'm happy. Thank you all for you help.


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## mywmyw (Sep 21, 2020)

good thing you socketed!


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