troubleshooting questions...

[strangegrey]

Hey folks...

I've got my first pedal (ross compressor clone) soldered together...and low and behold.  Nothing!

Part of me almost expected a doa, but I was hoping anyway.  I have a few questions...perhaps you guys can offer assistance:

1) Initially, I had miswired the battery leads.  You know, neg for pos and vice versa.  Could this have damaged the circuit in any way?

2) Im using Aron's pedal wiring diagram located here:

http://www.diystompboxes.com/beginner/circswled.jpg

Given this wiring diagram, even if the circuit isn't working...I should still see a the led light up?  Correct?  Because I'm not getting the led at this stage...

Obviously, I'm going to continue trying to methodically go over the schematic to make sure I didn't miss anything...

but as  I  continue, can any of you guys offer some pointers and/or advice while troubleshooting?

Thanks,
Frank

[strangegrey]

OK,

This is grand!

http://www.geofex.com/Article_Folders/mosswitch/mosswitch.htm

I'm thinking I borked something in the circuit.  What a stupid newbie mistake!  

What in the ross circuit could I have damaged, if anything.  The voltages I'm getting dont fall in line with what's posted over at fuzzcentral for this pedal....I can list specifics if needs be....

...but for now, The CA3080E at pins 6 & 7, which should be putting out ~2.7v and ~9.5v respectively are barely putting out .2...  Could I have borked this?

How about the 2N5088's? would these be susceptable to damage as well?


Thanks for any insight you guys can offer...


-Frank

p.s. man I feel stupid

[waldo041]

Given this wiring diagram, even if the circuit isn't working...I should still see a the led light up?  Correct?  Because I'm not getting the led at this stage...

Just a guess?
but is your 3pdt switch oriented the right way?

i'm sure you have checked all solder joints?

did you use sockets for the ic'sand trannies?

if not, get some(sockets) in there and order up some more ic's and trannies.

don't feel stupid!!!

remember, the only stupid question is the one not asked!!!

this forum is full of non working pedals, but most guys are willing to help get the majority working. just be sure to use the search function and read the Forum FAQs. follow what the EE's need to diagnose your troubles if you need them and they will chime in if they can. i'm a newb myself, so i hope that i may have helped.

peace, waldo

[strangegrey]

Just a guess?
but is your 3pdt switch oriented the right way?

I sure as hell hope so!

I used a continuity tester to ensure I had the thing wired correctly...and it does check out.  When I flip the switch power does go to the LED (and board) as intended and the board's input does indeed get a signal in...

i'm sure you have checked all solder joints?

Yea...that's something I'm fairly certain is ok.  I was very deliberate with the building of the board....however, I'm never going to say never on this.  I've seen freakier things happen...so I don't want to say it's perfect.  There might be something wrong on the layout or solder connections that is causing this.  so I will strive to double check later this evening....

did you use sockets for the ic'sand trannies?

I socketed the CA3080E....

I did not socket (and directly soldered to the board) the 2N5088s....

I was not aware that there were 3 pin sockets available...and if anyone has a mouser # for them, please shoot em my way.

if not, get some(sockets) in there and order up some more ic's and trannies.

That is my plan....

What still has me scratching my head...is the LED issue...and part of me wants to get to the bottom of that before anything else, since that might be indicative of some other problem I'm not aware of.

See...I've got the bat lead going to the middle upper lug on my 3pdt switch...from that same lug, a lead to the board's 9v in.

From the middle/middle lug of the 3pdt switch, I've got a lead that also goes to the board, where there are a 10K and a 15K in parallel....from the other end of those resistors, I've got a lead going to one end of the LED...and the other end of the LED to ground.

From what i can gather, there's nothing wrong with that scenario....and even if the board was borked, I should still get LED activity...

right?

-F

[aron]

From the middle/middle lug of the 3pdt switch, I've got a lead that also goes to the board, where there are a 10K and a 15K in parallel....from the other end of those resistors, I've got a lead going to one end of the LED...and the other end of the LED to ground.

If you are using input jack switching, you need to plug a 1/4" cable into the jack for the circuit to complete. Could that be the problem?

[strangegrey]

From the middle/middle lug of the 3pdt switch, I've got a lead that also goes to the board, where there are a 10K and a 15K in parallel....from the other end of those resistors, I've got a lead going to one end of the LED...and the other end of the LED to ground.

If you are using input jack switching, you need to plug a 1/4" cable into the jack for the circuit to complete. Could that be the problem?

That would be a much welcome cause of the problem...

But alas I am using input jack switching....and all my tests were with a cable plugged in...

[KORGULL]

This is probably a stupid question to be asking at this point but...
Are you absolutely sure you have the LED hooked up the right way around? And...
Did you try replacing the LED?

[strangegrey]

No suggestions are stupid...I welcome it all.

Tomorrow, my first troubleshooting step is to remove the board from the switch and just try to get the led to fire up.  If I remove the board and it fires up, they're related, if not...then they're unrelated.

just to verify on the led, I've got 9v heading to the board, where (independant of the circuit) I've got two resistors in parallel (a 10K and a 15K) giving me roughly 6K of resistance.  then from the other end of those resistors, I've got a lead going to the LED...and the other end of the LED goes to ground.  Am I missing something?

-F

[KORGULL]

I was wondering if you double checked that the pos+ and neg- of the LED are the right way around.
I have some LEDs that aren't consistent with the way(s) you can usually tell the negative lead from the positive. It can get confusing.

[strangegrey]

I was wondering if you double checked that the pos+ and neg- of the LED are the right way around.
I have some LEDs that aren't consistent with the way(s) you can usually tell the negative lead from the positive. It can get confusing.

I did....but I must've burned out the led or damaged it on insertion into the bezel...since It didn't work after I removed it.

I replaced the LED...hell even the bezel...and now the led works....making me feel better that the led issue was unrelated to the board issue.

Now I'm going to replace the above mentioned parts (when they arrive and see if that does anything.

-F

[petemoore]

As long as you're getting the recommended resistance range it should work fine for the circuit.
  , or figure out what type LED [they emit 'different spectrums of light that Certain LDR's may 'see' better] will activate that LDR to similar specs.

[Rick]

Another trick with leds if you're in doubt as to the polarity  ...just hold the led up to a light and look inside. You will see the two terminals. Inside the led the longer horizontal one of the two is the negative or cathode terminal. Just think of it as a  minus sign, so easy to remember. I believe this still holds true for most leds. Always open to any updates.   ...Rick

[KORGULL]

I have come across at least one batch of LEDs that have those terminals oriented the other way - so positive is the larger horizonatal one.
They are the "red blinders" from The Electronic Goldmine #G13713.
So far they are the only ones I've seen like that.
Both leads are the same length.
The body has a flat spot on the negative side - like most other LEDs I have.

[strangegrey]

The body has a flat spot on the negative side - like most other LEDs I have.

Yep, that's something I learned this week!

[KORGULL]

That flat spot on the case seems to be the most consistent way to identify LED cathodes. I've never found one yet that had the flat part on the positive side. I have come across some LEDs with the shorter lead being positive, where most of the time you find the short lead is the negative side. They may have been factory rejects since I got them at a surplus place.
I have alot of LEDs that have a perfectly rounded case with no flat side.
After dealing with so many inconsistencies with these identifiers, I use an LED tester or multi-meter most of the time now.

So, did you get that pedal running yet?

[waldo041]

I was not aware that there were 3 pin sockets available...and if anyone has a mouser # for them, please shoot em my way.

transistor sockets
http://www.smallbearelec.com/Detail.bok?no=147
(steve posts the mouser #)

breakaway any number you want sockets(up to twenty)
http://www.smallbearelec.com/Detail.bok?no=101

peace, waldo

[strangegrey]

So, did you get that pedal running yet?

The LED is working as intended...I replaced the LED and all is good there. I'm not sure if I borked the original led or I had it wired wrong...but the original, after I pulled it out...wouldn't light up when wired to a 9v with a resistor in series...so I think the led was fried as well.

The rest of the pedal is not working at yet.  Still no signal through the circuit.  I don't know if the transistors are fried....I wish there was a way to verify if the were good or bad, without removing them from the circuit.  If the trannies were OK, I might leave them in.

The IC *has* to be shot....I get voltage coming into it....and nothing coming out (when I should be getting about twice as much coming out of it.)  It could be a reason why the pedal is dead.

I've got replacement transistors, a replacement IC and some inline sockets for the transistors on order from Small Bear...if I need to replace them, I'll also pop in the sockets.

So I wont know for a few more days.  When the IC comes, I'll replace it and see what happens.  If after that, I still get nothing, I'm going to try to trace voltages again and see if I get any more clues.


Thanks for all the help so far....I'll keep you guys filled in!

-Frank

[KORGULL]

I don't know if the transistors are fried....I wish there was a way to verify if the were good or bad, without removing them from the circuit.

Here's a way you can try://www.geofex.com/fxdebug/trantest.htm