HELP! Carlsbad Reverb BTDR

[seagurt]

I bought a kit from Mammoth, the Carlsbad reverb, a unit that uses the Belton Brick BTDR2.

I completed the build 2 days ago, but the pedal isn't working.

I have built a few pedals, but I am far from complete in my knowledge of electricity. I am still learning, and hope this will be another good learning opportunity.

Here is the parts list, and build document I worked from.
https://moodysounds.com/wp-content/uploads/2014/09/carlsbad-reverb-assembly-instructions.pdf

Here are the symptoms;

The pedal has been tried in and out of the enclosure
The LED lights up, and I am getting power to the board (more on that later)
I am getting signal through on bypass, but nothing when engaged.
The switch appears to be fine, as do my Jacks and battery snap/Dc jack

Voltages read as follows;

J4- J201
G- -0.00v
S- .28v
D- 1.05v

J5- LM78L05acz
1-VOUT- 5v
2-GND- 0v
3-VIN- 9.58v

Q1-MPSA18
C- .52v
B- 0.01v
E- .34v

U2 (IC) TL072CP
1- 7.96v
2- 8.64v
3- 8.65v
4- 9.58v
5- 8.66v
6- 8.66v
7- 7.09v
8- 0v

Belton Brick BTDR-2H
1- 5v
2- 0v
3- .26v
4- 0v
5- .04
6- .04

I understand some of these numbers, and from my limited knowledge, it seems that maybe something is off with my J201, and/or MPSA18.

I do have an audio probe, and plan on throwing that at this problem later on if I can find the time. I thought I would try my luck, and post here, as I have always found it helpful to do so.

Here is a link to a few pictures of the PCB, with off board components, unboxed.
http://imgur.com/gallery/5ISB0

Feel free to offer any suggestions.

I appreciate the time and capabilities of all who chime in.

[m-Kresol]

first off, welcome to the forum. also thanks for sticking to the tech-help guidelines.

however, it is nearly impossible to help you without a schematic. Do you have no signal at all or do you only have dry (unaffected) signal when the effect is engaged?
It is possible - but could also be absolutely nothing, no way to actually confirm without a schematic - that the reverb brick is on the wrong side of the pcb. Most often the square pad indicates pin 1 (it does on madbean's moodring for example), which would mean the brick is supposed to go on the back of the pcb. on the other side, your voltages (assuming your pin voltages are numbered according to the numbers indicated on the brick) are fine. Do you have any pics of builds by other people that could confirm the arrangement? again, this is only guessing without a schematic, so please do NOT desolder anything yet as it can be a big pain in the ass to desolder ICs and possibly damage them.

good luck

[seagurt]

first off, welcome to the forum. also thanks for sticking to the tech-help guidelines.

Thank you, and it makes sense.

however, it is nearly impossible to help you without a schematic. Do you have no signal at all or do you only have dry (unaffected) signal when the effect is engaged?

I have asked the folks at Mammoth for a schematic, if available. I do have signal when the effect is bypassed, but no sound at all when it is engaged. Not even dry.

It is possible - but could also be absolutely nothing, no way to actually confirm without a schematic - that the reverb brick is on the wrong side of the pcb. Most often the square pad indicates pin 1 (it does on madbean's moodring for example), which would mean the brick is supposed to go on the back of the pcb. on the other side, your voltages (assuming your pin voltages are numbered according to the numbers indicated on the brick) are fine. Do you have any pics of builds by other people that could confirm the arrangement? again, this is only guessing without a schematic, so please do NOT desolder anything yet as it can be a big pain in the ass to desolder ICs and possibly damage them.

good luck

I originally wrote an email to Mammoth, to help with troubleshooting, and the gentleman saw the pictures I linked in this thread. He also said everything appeared to be in the right place. I'm sure that the brick being on the wrong side would have jumped out, but it is a possibility... From the PCB it looks like pin 6 (BTDR) has a square, the other pads are all circles. The numbers were taken from the brick pinouts, and they are labeled. 1 corresponds to pin one of the brick.

I do not have any pics of completed builds, but I will go looking now. If and when I get the schematic, I will post it.

Thanks again.

[gordo]

m-Kresol is right, the Belton should be on the bottom of the board so that Pin 1 is in the square hole.  Take your time unsoldering it (use desoldering braid if you have it) and you should be good to go.

[m-Kresol]

m-Kresol is right, the Belton should be on the bottom of the board so that Pin 1 is in the square hole.  Take your time unsoldering it (use desoldering braid if you have it) and you should be good to go.

I really wouldn't do that just yet and confirm it with mammoth first. Also, he would have dry signal if that's the only problem so this is possibly not the problem or there's something else.

[alanp]

One thing I remember from the Jargon File is that a true hacker considers troubleshooting to be a tete' a tete' with the original designer.

Lacking a schematic, emailing said designer would be my first thought.

[bluescage]

As far as I can see in the pictures, I think that U2 is placed the wrong way

[bluescage]

Looking at the pins of the Belton Brick, I think it's on the right side of the PCB because pin 1 of the Brick = 5V and pin 2 = 0V

[gtr2]

A build doc with no schematic. = epic fail....

[seagurt]

As far as I can see in the pictures, I think that U2 is placed the wrong way

That was indeed the problem, confirmed by Mammoth, and by my Carlsbad working! I originally had it in the right way, but was asked to flip it for debugging purposes, it may have been a bad chip from the get go, but I had a few TL072 CP's around, so I swapped it, and all is good!

One thing I remember from the Jargon File is that a true hacker considers troubleshooting to be a tete' a tete' with the original designer.

Lacking a schematic, emailing said designer would be my first thought.

Indeed, that is what I thought. Though I am still relatively ignorant on the maths behind solving a schematic (beyond simple things) any other kit I have bought had a schematic available, either online, or from the distributor. That being said, many have said the same things about the lack of a schematic!

A build doc with no schematic. = epic fail....

In the future, I will only be buying kits with schematics. Ths has indeed been a learning experience.

Thanks to all who have chimed in, and offered suggestions/solutions.

It is appreciated! Regards!

[bluescage]

Glad you solved it!

[m-Kresol]

yep good to hear it's working. have fun

[jbonaparte]

Do you have a picture of your board, i have the same issue. Exactly the same as you described. However, I 'think' my U2 is in the correct orientation. One thing I am unsure about, is the diode. The metal ends are a larger caliber than the holes that appear on the board, however, there are some wider holes more spaced apart that they fit in. I'm not sure where I am supposed to solder the diode, its a bit confusing and like others say, there are no images of a completed baord anywhere and no schematic.