Another pedal another problem

[Guybrush]

Looks like there's some different opinions on this. I'll just have to give it a try I guess.

Thanks everyone.

[RobA]

The easy way to get spec sheets is to just go to Mouser and search for the part. Their info almost always has links to the spec sheet. If they don't have it, you can find them on the manufacturers website. These are from National Semi, who was bought out by TI. So, TI's website search will get you this link,
http://www.ti.com/lit/ds/symlink/lm78l05.pdf

When you look at that doc, it's import to note that the diagram is from a bottom view. I hate it when they do that.

[Govmnt_Lacky]

+2 if you are using LM78L05 in IC3, it's backward...

If he is using the LM78L05A, when looking at the TO-92 with the flat side facing you and the legs down, the INPUT should be the RIGHT leg.

Judging by his circuit, and the orientation of the TO-92 in the pic above, it looks like it is correct to me  

[RobA]

I think the input on the board is off of the diode and not the side to the power wire.

Edit:
By input on the board, I mean the input to the regulator. The diode is inline in the schematic. It's not a crowbar.

[Govmnt_Lacky]

+2 if you are using LM78L05 in IC3, it's backward...

If he is using the LM78L05A, when looking at the TO-92 with the flat side facing you and the legs down, the INPUT should be the RIGHT leg.

Judging by his circuit, and the orientation of the TO-92 in the pic above, it looks like it is correct to me  

EDIT: CORRECTION... after looking more closely. IT IS IN REVERSED!! 

[TreeSlayer]

I think the input on the board is off of the diode and not the side to the power wire.

Edit:
By input on the board, I mean the input to the regulator. The diode is inline in the schematic. It's not a crowbar.

yup... 9v to diode, diode to leg 3i, leg 1o to PT2239+...

[Guybrush]

I think the input on the board is off of the diode and not the side to the power wire.

Edit:
By input on the board, I mean the input to the regulator. The diode is inline in the schematic. It's not a crowbar.

yup... 9v to diode, diode to leg 3i, leg 1o to PT2239+...

Sorry you have lost me a bit here. Are you still saying just switch the regulator around or is there another issue? Sorry if I'm being a bit dumb.

[RobA]

Yeah, you do need to change the regulator around. I was just explaining why it looks confusing. in the picture.

[TreeSlayer]

yes you do. I was just explaining that part of the power path. you'll get it...

[Guybrush]

Well I put a new regulator in the opposite direction but there's still no sound.

I'm stumped.

Thanks for all the help guys. It's really appreciated.

[RobA]

Have you tested any of these regulators on a breadboard just to be sure that they are working?

After that, you need to measure the voltages on your circuit. Check to see that you are getting the right voltages on each of the pins for the regulator and the IC's. Start by tracing the power path with the voltages and be sure they are what they should be.

There's a possibility that a part could have been blown when the regulator was smoking.

[RobA]

Also, do you have a link to the build doc/layout you built this one from?

[TreeSlayer]

+1! another part could be damaged. do you have an audio probe tester? you need to follow the audio path and see where the signal ends. then you know where to start...

[Guybrush]

I do have an audio probe into my test rig but I'm embarrassed to say that I don't know how to use it. My knowledge of schematics is non existent so any very basic pointers on how to use the probe would be appreciated.

Here's a photo of my test rig if anyone has the time to tell me how to use the audio probe.

 
Yellow=In, Red=9vt, Black=Grnd, Green=Out. Do I just attach everything as if I were testing the circuit or do I need to disconnect anything? Sorry, it's my first attempt to use it.

I think I may have bitten off more than one can chew here. It's my 4th pedal so thought I'd try something a bit more difficult but I'm starting to regret it!


Here's the build doc for the version I'm building http://tinyurl.com/kmqdx5a

[RobA]

Thanks for the build doc. I see why you put the regulator in that way. On the newer layout, it shows the regulator the other way around. But, the input power circuitry is basically the same. You do have to be careful with the regulators. The pinouts differ for different models of essentially the same regulator.

I can't see the whole resistor on your photo, but if R3 is a 5-band resistor, it looks like it could be a 1MΩ instead of 100kΩ.

It really helps to get used to working through a schematic. But, since you are tracing the audio on your actual board, you can do it from the layout image directly. You just listen to the audio at each pin starting with the input. When you can't hear it, that part and parts near by and their associated solder joints are suspect. You do need to know what your output pins are on your parts. Like you need to know that pin 5 is the output pin on the LM386. You can get that from the schematic or the spec sheet.

So, you trace the audio from the input to pin 2 on IC1, and then you come out pin 5 of IC1. From there you go to C4 and then R3, ... etc.