SHO Vero Layout match to schematic

Giordash · May 03, 2011, 12:27:08 AM

I have been toying with breadboard versions of this pedal for some time and decided to try my hand at a little more compact vero layout. It's one of those cases where you thiiiink it's laid out properly but you just want to make sure via forum opinion

One question I did want to ask was about the 9.1v zener diode across S and G of the BS 170. I read somewhere that by doing that, the other diodes can be taken out of the circuit completely - something about protecting the transistor from blowing out? Apparently this is a problem with some of the early versions of the SHO.

I'm still somewhat new to the building game. Any help would be much appreciated!

IvIark · May 03, 2011, 04:46:33 AM

The zener should go between gate and ground, not gate and source which was either a mistake in the trace, or a modification since by ZVex. With the zener in you can remove D1 and D2.

Giordash · May 03, 2011, 12:31:28 PM

I thought there was something fishy going on there. That makes much more sense.

Thanks IvIark!

Giordash · May 03, 2011, 12:51:21 PM

I cleaned things up a bit. The zener is going from gate to ground now and I took out D1 and D2. In theory, everything should work. No?

IvIark · May 03, 2011, 01:03:04 PM

Yes that looks spot on to me. If you want to save a bit of space you could always move C2 over to the left from the 7th to the 2nd column, move R4 left one space and save a column.

Giordash · May 03, 2011, 01:52:02 PM

Good call, IvIark. I didn't even see that! Thanks again for the help too. I'll post again once I've got it up and running.

Renegadrian · May 03, 2011, 08:56:00 PM

Giordash · May 04, 2011, 10:53:56 AM

So I got it at wired up, plugged in and nothing. Actually, I was getting some signal (about 25% of my bypassed signal) with the effect on but the effect was not coming through at all. In fact, I took the battery out while the effect was engaged and nothing changed sound-wise so that leads me to believe that the effect isn't coming through at all. Not sure what the problem could be. I've checked all connections twice, with the battery, with an adapter, checked the orientation of all the parts, the diode, 2 different true bypass wirings, I even insulated the floors of the enclosure to ensure nothing was grounding out. I have no idea what it could be...

IvIark · May 04, 2011, 11:06:16 AM

The layout definitely matches the schematic so have a look for bad solder joints would be the first job. Can you post a front and back pic?

Giordash · May 04, 2011, 11:24:17 AM

Photos of the front and back

bluesman1218 · May 04, 2011, 12:07:02 PM

Magnifying glass, good light, continuity tester or audio probe and a dental pick - check for micro solder bridges. Also double check your resistor values. I have had some measure fine before install and drift lower after powered up.

IvIark · May 04, 2011, 12:15:30 PM

Yes, good continuity between the track and the other side of the wires is a good check for a common problem area, check ground continuity between all ground points including offboard like the input and output sockets. Also you do have the diode cathode to gate don't you? Micro bridges between tracks often gets people so it may be worth scoring in between the stripboard rows with a knife to make sure there is definite separation.

Giordash · May 04, 2011, 12:27:07 PM

I can't tell for sure but there could be some bridging going on between tracks. And yes, the cathode is going to gate, anode to ground. I started scoring in between the tracks based on the reaction of the blade, it "feels" like there are some bridges. But when you look at it up close, it looks fine.

novakram · May 05, 2011, 01:21:38 PM

As a matter of course, run a Stanley blade / craft knife in-between each of the tracks (solder side).

I do that just to make sure while I'm still a newbie.

Might help?

squigglefunk · May 16, 2011, 06:12:04 PM

did you try a different BS170?

i've had builds where I had to swap it a few times to get a good one.

maybe I got a bad batch

compute88 · December 06, 2011, 09:51:56 PM

I tried building to this layout today, But No dice, Even tried a new Mosfet. Polarity is correct on the cap and zener.

Only thing different is I'm using a C5k rev audio pot. (perhaps this is giving me the issues?)

Used true Bypass 3pdt (input grounded) from this site
http://www.generalguitargadgets.com/diagrams/switch_lo_3pdt_ig_dcjack.gif?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a
I'm using mono input jack with no battery. 1k for the resister value with the LED.

Bypass works fine and passes signal just fine... When I switch it over, LED lights up, but passes no audio.

All grounds seem good, no layout rows jump (I checked with my Multi).
I'm thinking I wiring of the c5k needs to be different for the rev audio?

Quote from: Giordash on May 03, 2011, 12:51:21 PM
I cleaned things up a bit. The zener is going from gate to ground now and I took out D1 and D2. In theory, everything should work. No?

StereoKills · December 07, 2011, 12:34:42 PM

The zener diode really should be going across the BS170's Gate and Source as Zvex does. The pot doesn't need to be wired differently, you just have most of the sweep in the beginning of the rotation and very little towards the end.

compute88 · December 07, 2011, 01:32:04 PM

Every SHO schem that I can find shows gate to ground. hmmm...

DavenPaget · December 07, 2011, 01:36:22 PM

Quote from: compute88 on December 07, 2011, 01:32:04 PM
Every SHO schem that I can find shows gate to ground. hmmm...

Not really ...

StereoKills · December 07, 2011, 02:07:17 PM

If you're referring to this schematic, it is Zvex's earliest version. You would need a matching diode going to V+. Saves parts and is better practice to do one diode across Gate and Source.

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SHO Vero Layout match to schematic