Cardinal Tremolo help

[nativetrash]

Hi -

I've built a ton of projects over the last 2 years. I just built the Cardinal Tremolo from the 1776 board and I get a signal when the effect is engaged, it may be a little more treble tinged but there is no effect on it. I adjusted the trim pots, turned pots in every way possible but nothing. I can hear the thud of the tremolo in the background and the LED and this thud will increase when you increase the rate but it's not getting through to the signal.

Could this be from not biasing the transistors? I didn't socket them, but I'm in the process of desoldering them and putting in some sockets now.

I just wanted to see if this could be due to a different problem.

Thanks!

Patrick

[midwayfair]

The LED IS blinking? When you zero the depth, does the LED stay lit? Did you connect P1 to ground while testing the effect?

Any substitutions (did you use J201s and VTL5C1s)?

Measure the resistance across the LDRs. Do they change?

Audio probe the gates and drains of Q2 and Q3. Do you have signal?

What are your voltages (including the Tl072)?

[nativetrash]

I shorted p1 and p2 since I didn't care if it was always on. I used j201s and VTL5C1s - the j201s were from tayda so maybe they weren't great ones? I'll take some measurements tonight but I'm also halfway in desoldering the transistors. Thanks for the quick response though, I'll let you know once I get to the next step.

[midwayfair]

I shorted p1 and p2 since I didn't care if it was always on. I used j201s and VTL5C1s - the j201s were from tayda so maybe they weren't great ones? I'll take some measurements tonight but I'm also halfway in desoldering the transistors. Thanks for the quick response though, I'll let you know once I get to the next step.

The transistors won't be a big deal unless Q3 is just too low gain to bias correctly (which can happen once in a while with some of the fakes.)

In any case, the transistors won't be the source of the problem you've described, at least not directly. It would still be helpful to audio probe and see if the signal is making it all the way through the JFETs.

EDIT: How loud is that thud you described? You really shouldn't hear anything from the LFO.

[Stomptown]

How did you orient the VTL5C1's? Double check that the writing on them is face down on the PCB.

[nativetrash]

midwayfair - The thump was just "distant" sounding, hard to explain it in words. It's speed and intensity when up / down with controls. Also it's volume when up when the volume trim pot was turned.

stomptown - I positioned the vactrols w/ the "LED +" side facing upwards

[midwayfair]

midwayfair - The thump was just "distant" sounding, hard to explain it in words. It's speed and intensity when up / down with controls. Also it's volume when up when the volume trim pot was turned.

stomptown - I positioned the vactrols w/ the "LED +" side facing upwards

That means they're backward (good call Stomptown) ... for some reason the vactrol part in the library has the square pad opposite from LEDs, but the arrows in the symbol are still correct (they point to the cathode side). You'll have to flip the vactrols. Be really careful bending the leads back! They can snap off if you're not careful or too rough. Just go slow and use your needlenose pliers.

[nativetrash]

Ahh - I thought to myself too when building it "i wonder if I should keep some of the lead in case they are backwards" - i'll be careful and hopefully I can get them switched around without any problems.

thanks for the help!

[Stomptown]

midwayfair - The thump was just "distant" sounding, hard to explain it in words. It's speed and intensity when up / down with controls. Also it's volume when up when the volume trim pot was turned.

stomptown - I positioned the vactrols w/ the "LED +" side facing upwards

That means they're backward (good call Stomptown) ... for some reason the vactrol part in the library has the square pad opposite from LEDs, but the arrows in the symbol are still correct (they point to the cathode side). You'll have to flip the vactrols. Be really careful bending the leads back! They can snap off if you're not careful or too rough. Just go slow and use your needlenose pliers.

Yeah, I was guessing that might be it. I've done it before myself and just populated my cardinal so I knew it would be an issue. FYI, you can mirror the vactrol part in eagle in order to flip it so the writing is face up. I think Brian does this with all of his designs. Just thought I'd share in case you ever design something using a vactrol, which I'm sure you will! 

[jimilee]

midwayfair - The thump was just "distant" sounding, hard to explain it in words. It's speed and intensity when up / down with controls. Also it's volume when up when the volume trim pot was turned.

stomptown - I positioned the vactrols w/ the "LED +" side facing upwards

That means they're backward (good call Stomptown) ... for some reason the vactrol part in the library has the square pad opposite from LEDs, but the arrows in the symbol are still correct (they point to the cathode side). You'll have to flip the vactrols. Be really careful bending the leads back! They can snap off if you're not careful or too rough. Just go slow and use your needlenose pliers.

Yeah, I was guessing that might be it. I've done it before myself and just populated my cardinal so I knew it would be an issue. FYI, you can mirror the vactrol part in eagle in order to flip it so the writing is face up. I think Brian does this with all of his designs. Just thought I'd share in case you ever design something using a vactrol, which I'm sure you will! 

Wasn't the cardinal his design?

[Stomptown]

Yeah, but Josh designed the PCB for the Cardinal. A  great design too!

[jimilee]

Yeah, but Josh designed the PCB for the Cardinal. A  great design too!

oh. Mine is halfway populated right now. Looking forward to finishing it up.

[nativetrash]

I ruined something in the process of desoldering the vactrols and putting a new J201 in.

I'm going to have to just start from scratch once I can afford to buy the board and the vactrols again.

[midwayfair]

I ruined something in the process of desoldering the vactrols and putting a new J201 in.

I'm going to have to just start from scratch once I can afford to buy the board and the vactrols again.

Almost everything's salvagable. What's not happening?

[gtr2]

If the board is beyond repair.  I will gladly replace it for you.  Just shoot me a PM.

Josh