Valvecaster Help

Johnny Halo · August 25, 2008, 03:59:46 PM

Finally got to build the Valvecaster. Decided on the toneless version.

Went pretty well. Except that when I hit the switch and engage the effect, I get no signal and a loud hum. It does not happen until the volume is at about 3 and does get louder as you turn it up. The gain pot does nothing.

Any help would be appreciated.

frequencycentral · August 25, 2008, 04:04:32 PM

Probably an unfiltered unregulated power supply?

Look at the voltages I posted on the original thread and compare yours to them.

Johnny Halo · August 25, 2008, 04:45:16 PM

I tried it with a Boss ACA 120 - DC 9 volt.

Renegadrian · August 25, 2008, 05:07:55 PM

Did you follow my layout? I tell you it's more than verified. IT MUST WORK!!!

Check all the connections, grounds (there are many) and pots.
Try another PS if you have another handy and try at 12V.
Try another tube (but I doubt it's a tube thing...)
Try again, you'll be luckier.
Try gardening, it's said its more relaxing than non working stompbox DIY!

(sorry, I am stupid---)

Renegadrian · August 25, 2008, 05:09:38 PM

Did you put a 3PDT or a DPDT???

MikeH · August 25, 2008, 06:00:20 PM

Follow the "Debugging" protocol and post some voltages.

Johnny Halo · August 25, 2008, 09:08:52 PM

O.K. don't have it in front of me (at work), but I did the PTP version with no tone. I used the original layout with Renegadrian's "no tone" one to cross reference.

Can provide more details later.

Thanks.

FlyingZ · August 25, 2008, 10:20:10 PM

Mine has a loud hum at 9v even with the regulator. Works perfectly at 12v.

kurtlives · August 25, 2008, 11:17:00 PM

Quote from: FlyingZ on August 25, 2008, 10:20:10 PM
Mine has a loud hum at 9v even with the regulator. Works perfectly at 12v.

Are they two different power supplies?

I think the 9V has its polarity messed up.

FlyingZ · August 25, 2008, 11:39:09 PM

Variable power supply (3, 4.5, 6, 7.5, 9, 12).

The hum was also noticeable with a 9v battery.

Again 12v works without flaw

Johnny Halo · August 26, 2008, 02:57:08 AM

Just a quick update - 12 volt supply got rid of (most of) the hum.

Still no signal when engaged.

Jimmy-H · August 26, 2008, 03:32:09 AM

Quote from: Johnny Halo on August 26, 2008, 02:57:08 AM
Just a quick update - 12 volt supply got rid of (most of) the hum.

Still no signal when engaged.

Hi Johnny,

I guess there is something wrong with the wiring.

Can you post some pictures?

Renegadrian · August 26, 2008, 05:12:51 AM

Quote from: Johnny Halo on August 25, 2008, 09:08:52 PM
O.K. don't have it in front of me (at work), but I did the PTP version with no tone. I used the original layout with Renegadrian's "no tone" one to cross reference.

Have a look at this, it shoulda be that way, I believe...

Johnny Halo · August 26, 2008, 01:30:30 PM

Here's a photo - not sure if it will help or not.

Changes to original layout include full size pots, volume (center) is Alpha B100K, and 12AT7 tube. The resistors on the socket are touching each other- but not the leads. All the parts, except for switch are from Radio Shack.

I tried taking the switch out of the circuit and got no signal at all. With switch, signal comes through in bypass mode.

Not sure where to test with meter for voltages, signal, etc.

The box is vintage. I was holding off showing the front until the big reveal.

Thanks, everybody.

frequencycentral · August 26, 2008, 01:45:18 PM

Quote from: Johnny Halo on August 26, 2008, 01:30:30 PM

Not sure where to test with meter for voltages, signal, etc.

You need to measure the voltage at all nine pins of the tube socket (with the tube in the socket), and post them.

Here's mine from my fully functional (sorry!) Valvecaster:

Pin 1: 3.02v
Pin 2: -0.518v
Pin 3: 0.00v
Pin 4: 0.00v
Pin 5: 11.97v
Pin 6: 8.21v
Pin 7: -1.285v
Pin 8: 0.00v
Pin 9: 5.91v

DC power in is reading 11.99v.

Gain at maximum.

My gain pot is 100K not 50K, but that shouldn't make a difference - just set yours to maximum gain too.

Renegadrian · August 26, 2008, 01:50:29 PM

It seems correct at a first sight...The usual valve is 12AU7, while some ATs can still sound good.
You could try to put in a 12AU7 if you got one. Also try to put a DPDT, after all I see there are no LEDs so...
How are you going to use that extra big hole? What was that for? Now I'm curious...

MikeH · August 26, 2008, 01:53:18 PM

The fact that you get no sound what-so-ever make me think the likely scenario is that you've got something touching that shouldn't be, or vice versa. Get youself a continuity tester (you may already have one on your DMM) and check to make sure everything that should be connected is, and everything that shouldn't be isn't. Start by checking for continuity between ground (sleeve of input jack) and everything that's not supposed to be grounded.

Renegadrian · August 26, 2008, 01:54:11 PM

I checked again the 3PDT wiring, I used the usual GGG layouts wiring, and I made 2 valvies with a 3PDT. So that is not the problem...Did you check the DC jack polarity???

Johnny Halo · August 26, 2008, 04:02:37 PM

I have an analog meter - sorry, I am old school. With it set on RX1K(ohm) and touching pins 1, 2, 6 & 7 I got no response. All other pins made it move.

I have the adapter set for negative tip.

Where should I put a probe to test the voltage of the pins, if I can using my meter.

If all goes well, the big hole just might get an led.

MikeH · August 26, 2008, 04:07:33 PM

So that means 1, 2, 6 and 7 aren't grounded, right? That's good, but pin 5 should not be connected to ground. Neither should pin 9. Make sure they're not. Also make sure your input and output aren't connected to ground when the effect is engaged.

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Valvecaster Help