Marsha valve PCB? And verified?

davepedals · May 27, 2017, 06:51:48 AM

Does anyone know of a verified pcb for the Marsha valve? I've built 8 different pedals in the last month with my own pcb layouts and all of them work. Built three different layouts for the Marsha valve and 'none' have worked! I'm not that experienced with PCB design; yet about 90% of my layouts work the first time... by luck I guess. I have looked over my layout many times and I just cannot see where I went wrong! Eyes can play tricks!

Could someone please take a look at my layout and tell me where I've screwed up? I sure would appreciate it! A re-draw would be great.
Below is a "sho" I built for a friend, works like a charm! Below it is my 'non-working' pcb layout for Marsha Valve (J201 Transistor) Thanks for any help!

Marsha Valve:

niektb · May 27, 2017, 07:56:11 AM

What exactly do you mean with 'not working'? No sound? Too much noise?

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Kipper4 · May 27, 2017, 08:34:44 AM

What are the dc voltages telling you?

Cozybuilder · May 27, 2017, 01:42:22 PM

The PCB drawings both match the schematic. Looking at your PC, it looks like there are mistakes. Did you breadboard the circuit?

davepedals · May 27, 2017, 05:43:29 PM

No didn't breadboard. Simply doesn't work. I think I screwed up with my layout. Was really just wanting someone with better pcb design skills to check my pcb against the schematic for accuracy. I enjoy making pcbs so if there is a mistake I'll just redraw and try another one. Thinking the pot may be in the layout incorrectly.

niektb · May 28, 2017, 02:07:57 AM

Did you triple check the pinouts of the JFET and the rotary pots?

And did you configure the trim pot correctly?

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Kipper4 · May 28, 2017, 02:18:26 AM

Your layout looks fine to me too.
Which fet did you use?
What are the voltages?
Even if the pot is wired backwards it would work but backwards.
did you try with the pot at both extremes?

davepedals · May 28, 2017, 04:41:21 AM

Trim eh? You know what that may just be what the problem is! The only time I have ever installed the trim was with a PCB I got from a professional company. Never tried installing one on my own layouts, so I was never quite sure which way it should be oriented to be honest.

The three layouts before that did not work I cannot tell you at this time how the trim is laid out, perhaps when I get inside. However I just built a new one but haven't tested it yet... this is how I have the trim laid out on the new one below. As you can see in the photo the top part of the trim goes to +9V, while the two bottom legs are tied together and go to the drain of the J201 transistor. That looks correct to me.

Ice-9 · May 28, 2017, 05:34:01 AM

Quote from: davepedals on May 28, 2017, 04:41:21 AM
Trim eh? You know what that may just be what the problem is! The only time I have ever installed the trim was with a PCB I got from a professional company. Never tried installing one on my own layouts, so I was never quite sure which way it should be oriented to be honest.

The three layouts before that did not work I cannot tell you at this time how the trim is laid out, perhaps when I get inside. However I just built a new one but haven't tested it yet... this is how I have the trim laid out on the new one below. As you can see in the photo the top part of the trim goes to +9V, while the two bottom legs are tied together and go to the drain of the J201 transistor. That looks correct to me.

The pin at the top is the wiper of the trimmer and the two (which you have connected together are the ends of the resistance). Connections should not be this way. Connect the wiper to one end of the resistance and the other end to the drain of the JFET.

Kipper4 · May 28, 2017, 05:47:40 AM

Kipper4 · May 28, 2017, 05:50:32 AM

The layout looks right unless he bent the trimmer legs though.

Last time of asking

Voltages?

anotherjim · May 28, 2017, 08:13:33 AM

You do see on the schematic where it says "adjust trim for 4.5v at the drain". That is an instruction, not optional.

The 100k trimmer appears correctly laid out in this image. I don't see anything corresponding to it in the build.

Have you made component value changes?
I see something in this...

... that black object is a trimmer? Value reads 103. That's 10000 or 10k . 100k would be 104 (10 and 4 zero's).

davepedals · May 28, 2017, 09:15:29 AM

Quote from: Kipper4 on Today at 09:47:40 AM<blockquote>

</blockquote>Because this trimmer has the two legs on one side, then the other across from them I would've never imagined that it hooked up the way you have shown here. Thanks for pointing that out!

Yes – I know I need to adjust the bias.

No – no components were changed out.

The actual photo of the PCB you're looking at is another project I did, a "sho" simply to illustrate that I'm not a sloppy builder.

My meter is on loan for a couple of days, meanwhile I'll correct orientation of the trim and try it out again. I don't know how close the trim has to be to 4.5 v but I may be able to do it by ear until I get my meter back. Thanks for all the help everyone! I'll update as soon as possible. You know I have built stereo FM transmitters before so when a simple project like this does not work it really blows my mind.

davepedals · May 28, 2017, 09:29:19 AM

Anotherjim, the object you are seeing is from my "sho" pedal PCB. The 103 is a capacitor , 0.1 UF.

Ice-9 · May 28, 2017, 10:14:36 AM

Quote from: davepedals on May 28, 2017, 09:29:19 AM
Anotherjim, the object you are seeing is from my "sho" pedal PCB. The 103 is a capacitor , 0.1 UF.

103 = 10n (0.01uF)
104 =100n (0.1uF)

davepedals · May 28, 2017, 10:33:52 AM

Early morn decimal mistake!

Quote from: Ice-9 on Today at 02:14:36 PM<blockquote>

Quote from: davepedals on Today at 01:29:19 PM<blockquote>Anotherjim, the object you are seeing is from my "sho" pedal PCB. The 103 is a capacitor , 0.1 UF.
</blockquote>

103 = 10n (0.01uF)
104 =100n (0.1uF)</blockquote>

Cozybuilder · May 28, 2017, 01:04:03 PM

I'm confused now. Is the PCB you posted from the SHO or from the Marsha Valve? It certainly does not appear to match up with the MV layout. Can you post clear photos of your Marsha Valve PCB?

davepedals · May 28, 2017, 02:00:56 PM

Just re-read my last paragraph:

"Below is a "sho" I built for a friend, works like a charm! Below it is my 'non-working' pcb layout for Marsha Valve (J201 Transistor) Thanks for any help!"

Seems clear to me... look for the sea foam green!

Quote from: Cozybuilder on Today at 05:04:03 PM<blockquote>I'm confused now. Is the PCB you posted from the SHO or from the Marsha Valve? It certainly does not appear to match up with the MV layout. Can you post clear photos of your Marsha Valve PCB?
</blockquote>

davepedals · May 29, 2017, 02:27:51 AM

The way, cozybuilder... I did not mean for my reply to sound smart assed, sometimes my attempt at humor are better left unsaid.
(OR)
Dave needs some sleep!

Cozybuilder · May 29, 2017, 11:38:48 AM

No offense taken. If you could post photos of your Marsha Valve, hopefully one of us can spot something that will help.

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Marsha valve PCB? And verified?