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DIY Stompboxes => Building your own stompbox => Topic started by: MontyS12 on May 25, 2020, 06:39:16 PM

Title: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on May 25, 2020, 06:39:16 PM
Hi all. It's newb-city over here. Valvecaster build is complete but the tube does not get any power. With the tube plugged into socket, absolutely nothing works. When the pedal is placed in signal chain, it passes no signal whether the switch is engaged or not. With the tube pulled out of socket, the LED comes back on and a signal passes through but is quieter than when pedal is removed from chain. I've done every continuity test that I know to do, including testing the socket terminals and, of course, the tube itself. Those check out fine as well. I've also checked and redone any questionable joints and slowly traced and retraced every connection against the wiring diagram with no mistakes found. Interesting note which could just be happenstance: I originally had a DPDT switch in it and the pedal worked then. Replaced it with a 3PDT switch so I could have an LED. It's been in mystery mode ever since. Any ideas off the top, folks?

This is how i wired the switch:  (https://i.postimg.cc/Z0GKY9m0/image.jpg) (https://postimg.cc/Z0GKY9m0)

This is the diagram I used for the rest:

(https://i.postimg.cc/DmXnN2Gh/matsuminvalvecasterlayout.gif) (https://postimg.cc/DmXnN2Gh)
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: Marcos - Munky on May 25, 2020, 08:08:29 PM
With the tube plugged into socket, absolutely nothing works. When the pedal is placed in signal chain, it passes no signal whether the switch is engaged or not. With the tube pulled out of socket, the LED comes back on and a signal passes through but is quieter than when pedal is removed from chain.

Interesting note which could just be happenstance: I originally had a DPDT switch in it and the pedal worked then. Replaced it with a 3PDT switch so I could have an LED.
So, that means something is shorted, probably something power related, or you're grounding something that isn't supposed to be (well, still power related).

First, let's check if you're shorting something related to V+. Plug the tube, power the pedal, plug in some cables if you used stereo jacks. Don't need to plug anything else, no amp, no guitar, nothing. Measure voltages between pins 4 and 5 of the tube.

Also, take out the tube and measure the resistence and continuity between pins 4 and 9, 5 and 9 and 4 and 9 of the tube. Just to be sure the heaters are ok. They're probably ok.

Photos of your build may help a lot. Mainly the switch, since it was working before you changed it. The switch diagram, while it's not one I'd use, is correct, but that ground jumper could be done way better (that's why I woudn't use it).

Also, welcome!
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: willienillie on May 25, 2020, 08:39:07 PM
Just a guess, footswitch rotated 90 degrees?
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on May 25, 2020, 09:54:04 PM
Thanks, Marcos - Munky for the reply and the welcome! Ok, I measured the voltage between pins 4 and 5 on the socket with tube plugged in, powered and cabled and got nada. Tube unplugged, resistances between 4,9 and 5,9 both read .03. I also did get continuity and reading was .001 for both tube pin positions. The switch is in the correct orientation, by the way. Pics coming in a moment but my camera is somewhat garbage-y...
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on May 25, 2020, 10:01:34 PM

(https://i.postimg.cc/Z9tQsyGt/IMG-20200525-180257791.jpg) (https://postimg.cc/Z9tQsyGt)

(https://i.postimg.cc/N9GpZ8bV/IMG-20200525-180106354-HDR.jpg) (https://postimg.cc/N9GpZ8bV)
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: Marcos - Munky on May 25, 2020, 10:45:25 PM
Ok, I measured the voltage between pins 4 and 5 on the socket with tube plugged in, powered and cabled and got nada.
That answers to my first suspect thing: there's a short between v+ and ground somewhere. The reason is because you said the led doesn't work when the tube is plugged in, but works when the tube is removed from the circuit. The tube is causing a short on the power lines, then you get zero volts between pin 4 (which is connected to ground) and pin 5 (which is connected to v+) and, since your power supply is shorted, nothing gets power, neither the led, which is connected directly to the power supply.

Just to be sure, do the exact same voltage measurement, with cables and power but without the tube pugged in.

Also, I'll ask you for two extra tests. Without the tube (cables and power are not required), check the resistence of R2 and R3 with the multimeter. And then, with the tube plugged in but no cables and power, check for continuity between all the pins. I mean, put one probe on pin 1 and check all the others, then put one probe on pin 2 and check all the others... Let us know if you get continuity between any pins (some continuity are actually expected, I'll say more on that after you post the results).

Edited: wait wait wait! I checked your photos. Before doing any of those tests, see the leg of C2 that's connected do pin 1? It's so close to pin 9. When you plug the tube, the socket move a little bit, and probably pin9 is being connected to that leg. Try to move that leg a little bit, or insulate pin 9 of the socket, and see if it works. If not, then do those tests I've asked.
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on May 26, 2020, 12:30:48 AM
Marcos, I really appreciate your help, sir. So, isolating pin 9 wasn't the culprit, sadly. I won't get to the resistor testing until tomorrow at the earliest. I was able to do a comparison voltage test between terminal 4 and 5 on the socket, without the tube plugged in, and got a reading (2.84v, I think it was). The continuity test between the socket terminals went as follows: Pins 1-3 no cont, Pin 4 had cont to 5 and 9, Pin 5 had cont to 4,5,8 and 9, Pins 6-7 no cont, Pin 8 has cont to 4,5 and 9 with 8 to 4 having a cont reading of 0, Pin 9 had cont to 4,5 and 8. Every continuity reading I got was between 7 and 14 except the Pin 8 to 4 reading of zero. Thanks, again.
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: FiveseveN on May 26, 2020, 02:27:51 AM
When the pedal is placed in signal chain, it passes no signal whether the switch is engaged or not.
This clearly indicates an issue with the switch or jacks, because in bypass mode that's all that is involved, the rest of the circuit is irrelevant. It may not be the only issue, but you have to at least get signal in bypass.
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: willienillie on May 26, 2020, 04:54:54 AM
It's not too clear in the picture, but it looks like neg (black wire) from the power jack is going to something other than the sleeve lug on the (assuming) input jack.  That's a switching mono jack, which is okay for this, but don't connect anything to the switch part, only use tip and sleeve.

Edit:  I should say, you don't need to use the switch feature, but you do have the option to ground the tip when the input cable is pulled out, if you so desire.  In that case, just connect the switch lug to the sleeve lug.
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: Marcos - Munky on May 26, 2020, 08:19:35 AM
Marcos, I really appreciate your help, sir. So, isolating pin 9 wasn't the culprit, sadly. I won't get to the resistor testing until tomorrow at the earliest. I was able to do a comparison voltage test between terminal 4 and 5 on the socket, without the tube plugged in, and got a reading (2.84v, I think it was). The continuity test between the socket terminals went as follows: Pins 1-3 no cont, Pin 4 had cont to 5 and 9, Pin 5 had cont to 4,5,8 and 9, Pins 6-7 no cont, Pin 8 has cont to 4,5 and 9 with 8 to 4 having a cont reading of 0, Pin 9 had cont to 4,5 and 8. Every continuity reading I got was between 7 and 14 except the Pin 8 to 4 reading of zero. Thanks, again.
Ok, the continuity test is fine. You should have continuity for pins 4, 5 and 9 together, since they're for the heaters and the heathers have so low resistence. Also, since pin 4 and pin 8 are connected to ground, there should be continuity between all of them, with some having less resistence than others.

But the reading of 2.84V on the pins 4 and 5 without the tube shows some else is wrong. Those pins are directly connected to the power supply. I don't know what you're using to power this circuit, but measure the voltage directly on the power supply plug, without connecting it to the circuit.

As pointed by FiveseveN and willienillie, there are other issues. I'll try to trace the wiring from your photos to see if I can find something else.
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: Marcos - Munky on May 26, 2020, 08:49:58 AM
Ok, so far what I got is the middle pot being the gain one. Central lug is going to pin 3, lug 3 is going to ground. That's fine. All the rest of the circuit on the tube socket seems fine. The left pot (looking from the bottom) is volume, ok.

But I can't really understand what's going on with your tone pot. You should connect v3 and t3, but seems to had connected v3 and t1, so the tone will be reversed (no issue). There's a cap from lug 2 to ground, ok. But I can't understand what you did for the other lug (on the layout is lug 3 but since you reversed it it's lug 1).

Cap going out of lug 3/1, ok. But the other end of the cap should go to pin 6 of the tube, but from what I can see you're connecting cap, pin 6 and lug 2 of the tone pot together, correct? They shoudn't be connected to lug 2 of the tone pot. This won't solve the bypass problem, but maybe will help to solve part of the other problem.

For the bypass, your switching is correct. But your input jack isn't. As pointed out by willienillie, you're using a switching mono jack, while the switch wiring picture you posted uses a non switching stereo jack. They indeed both works for effects building, but they have different features.

A non switching stereo jack is wired with signal on tip, ground from power supply on ring and ground from everything else on sleeve. The plug used for guitar signal is mono, so it have a big sleeve instead of a sleeve and a ring. That means ground from power supply is disconnected from the circuit when there's no plug on the jack, and when you put the plug the big sleeve of the plug connects the sleeve and ring connections of the jack, and now the power ground is connected to the other grounds. It works as a "power supply on/off" switch.

A switching mono jack have the same number of terminals as a non switching stereo jack, but they work way different. You don't have sleeve, tip and ring as on the other jack, but sleeve, tip and switch. When there's no plug, the switch is connected to the tip. When you put the plug, the switch is disconnected from the tip. That means, if you're connecting the power ground to the switch, with the plug removed you're swnding it to the input of the circuit, and with the plug inserted you're disconnecting it from everything, so basically removing power from the circuit.

This doesn't explain the "with tube/without tube" behavior, but you should correct it. Connect all ground points to the sleeve, including the "negative" wire from the power jack.
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on May 26, 2020, 06:14:15 PM
Again, massive appreciation to you guys. Without the time to really analyze anything technical right now, the glaring question in my mind is: "How the hell did this dumpster fire even work in the first place?" Also, it sounded AMAZING. Weird, huh?
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: Marcos - Munky on May 26, 2020, 06:53:03 PM
Some things really doesn't have a logical explanation :icon_lol:

Since you're more experienced now than when you built it at first, and if you have to do some good rework to make it work again, maybe you should consider to build it from the beginning all over again, doing it cleaner and with things like different color wires to make it more beautiful to look at (even if it's inside of a box) and easier to debug if needed (hope you don't need to). I mean, your ptp skills are way better than mine, but I'm sure you can make it even better. But that's assumin there's lots of stuff to do and if you want to. Maybe it's just a matter of changing a wire or two, and you don't feel the need to rebuild the already working parts.
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on May 26, 2020, 07:16:01 PM
Yeah, I've definitely thought about starting over...
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: Marcos - Munky on May 26, 2020, 08:00:57 PM
But first let's find the problem.
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on May 31, 2020, 03:11:16 PM
Ok, gentlemen, it took me almost a week to have any real time to concentrate on this project again. Finally got back to it and it now works! Quick breakdown: putting the power supply ground wire to the sleeve of the input jack, per willienillie's suggestion, rather than on the lug that I thought was the ring, solved the tubes power problem AND the LED shorting when plugging in the tube problem, which I did not expect to solve both. After this, there was still no signal or bypass signal, in part I guess, because I had the wire from lug 7 on the switch also going to the wrong jack lug ( I had decided, before anything else, to wire up a new switch to a more common configuration and made ,basically, the same jack mistake that I had made with the power supply). When I corrected that, I had signal in bypass again but no non-bypass signal. Then, I rerouted the wire going from V3 to T1 so that it went V3 to T3, per Marcos - Munky's suggestion and then...DISCO! All working again and sounds fantastic! Guys, I cannot thank you enough for your kind help!! I only hope that I develop enough knowledge to able to return the favor. CHEERS!!!
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: Marcos - Munky on May 31, 2020, 04:05:08 PM
Nice to know you got it working!
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on June 01, 2020, 10:54:17 PM
Oh well. Short honeymoon. Now I'm getting intermittent power loses. It seems after the pedal has been on for a little while, it starts cutting out. LED, signal everything. It cuts out in a way that's almost rhythmic. Every 3-4 seconds and for only a fraction of a second at a time. Does this sound familiar to anyone?
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: Marcos - Munky on June 02, 2020, 01:21:53 AM
What are the specs of the power supply you're using?
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on June 03, 2020, 01:41:44 PM
It's a 9 volt, DC jack. That's as much as I know.
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: Marcos - Munky on June 03, 2020, 04:42:40 PM
It could be the power supply. Try to use another one (check the plug pinout).
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on June 05, 2020, 11:11:02 PM
What I'm plugging it into is just a standard 9v tap from my pedal board.
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on June 08, 2020, 04:26:46 PM
Ok. Swapped the DC power jack and i got the same behavior. With pedal plugged in and no tube, I get 9.04v. With tube inserted and plugged in to power, I get a reading of 8.61v
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: Marcos - Munky on June 08, 2020, 04:40:01 PM
How much current is the tap of your pedalboard capable to output? Tube circuits requires way more current than opamp circuits, so maybe your power supply can't handle the current.
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on June 08, 2020, 06:21:16 PM
Ah, good question. Apparently only 100ma or 200ma depending on which taps are used....
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: MontyS12 on June 08, 2020, 07:24:10 PM
yeah, I've had it on a 600ma adapter separate from my pedalboard and it has not repeated the behavior. Hope that was it. Had complete forgotten that milliamperage on my dc brick was so low...
Title: Re: Yet another PCB-less Matsumin Valvevaster question
Post by: Marcos - Munky on June 08, 2020, 07:35:49 PM
So that's probably the cause of the issue. It's not your dc brick that have low amperage, it's the tube that draws too much current. A tube screamer draws about 7.5mA, so you can power 13 tube screamers with the 100mA tap. On the other hand, a tube draws 150mA just for the heaters when you power them with 12V.