Build Your Own Clone Message Board

I just built a Silver Pony. It works, and if I made any mistakes, it's certainly not obvious!

...Except for one thing, and I'm not sure if this is a problem or the way it's supposed to be: is the level/volume strictly a "cut", or is it also supposed to be a boost as well? On mine, if the level pot is all the way counter-clockwise, then the pedal is completely silent. It feels like unity is around 80% clockwise, so fully clockwise is just a tiny boost.

I'm comparing it to a Moskey Silver Horse (super cheap Klone): on that, unity is right around 50% (as expected), and fully clockwise results in a fairly significant boost.

Ironically, this is actually how I like to use this pedal, with the gain all the way down and level all the way up as a boost.

Hmmm, sounds like perhaps you have a pair of resistors swapped or something similar. With the gain all the way down on my SP, unity volume is achieved with the level pot set just below 12 noon (assuming that full CCW is 7 o'clock and full CW is 5). With the gain up to 9 o'clock (which is where I like to run my SP for a clean boost), unity volume occurs at about 9 on the Level pot, as well.

Suggest that you post some photos of the build and let us have a look. These need to be large, well-lit, well-focused shots of the PCB and all of the jack and switch connections.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Here's to hoping it's a simple problem... I went through and double-checked all component values, and looked for obvious solder problems. I don't see any obvious problems, but I've overlooked simple things even after multiple checks. Nice to have additional eyes looking for problems!

Here are three pics of the component side. Let me know if these pics are inadequate.

...and three pics of the bottom/solder side. (Obviously you can't see under the gain pot, but I'm hoping we can find the issue without having to remove that.

Thanks!

My Silver Pony hits unity volume about 12 noon at zero gain and has lots more on top. Is the bottom of the gain pot insulated (use a tab of electrical tape) - it could be grounding out something?


Sent from my iPad using Tapatalk

Hard to show in a picture, but I could clearly see plenty of air gap between the gain pot and the circuit board.

Either way, just to be sure, I went ahead and flossed in enough electrical tape to completely cover the bottom of the pot.

Couple of ideas:

1. The first thing I would do is to pull and re-seat all three IC's in their sockets, taking care that the legs are precisely aligned with their respective socket slots and that they are seated all the way down into the socket. Then re-test the pedal to see if that makes any difference.
2. If no change, it would be worth taking a set of DC voltage readings on the pins of each of the three ICs. The pin numbering is as shown in the attached image below. Report the results here, please.
3. Most of your soldering, particularly for the components on the PCB, looks quite good. There are a few joints that could stand improvement, however. Carefully inspect the board and touch up any suspicious joints--those that look blobby, dull, misshapen, or which don't completely cover the solder pad. I would re-flow ALL of the wire connections at both ends, as well as the pot leg connections, since these are super-critical and a bit more difficult to insure good contact than the component connections. Also, if you see wire or component ends protruding past the solder joint, it's a good idea to trim them down to avoid possible signal or voltage shorts. However, I would hold off on this third action until you complete the first two.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thank you for the help! Finally got some time to try the first two:



I re-seated the ICs, as you suggested: no change. I also tried with battery (previously using my pedal board PSU), just because it's an easy test. Also no change.

So with a 9V battery as the supply, I got the following IC pin voltage readings:

IC2 (top TL072/closest to input/output jacks):
pin 1: 4.46v
pin 2: 4.49v
pin 3: 4.43v
pin 4: -8.18v
pin 5: 4.42v
pin 6: 4.48v
pin 7: 4.50v
pin 8: 15.96v

IC1 (lower TL072/closest to footswitch):
pin 1: 4.47v
pin 2: 4.47v
pin 3: 1.21v
pin 4: 0v
pin 5: 4.36v
pin 6: 4.47v
pin 7: 4.47v
pin 8: 8.93v

Charge pump:
pin 1: 8.90v
pin 2: 4.59v
pin 3: 0v
pin 4: -3.95v
pin 5: -8.11v
pin 6: 4.18v
pin 7: 3.80v
pin 8: 8.90v

All readings were referenced to the battery's negative (-) terminal.

When I finished the readings above, I checked the battery: 8.90v.

Thanks again!

edit: used IC labels from schematic, and TL072 pinout for reference:

pin 1: 1OUT
pin 2: 1IN-
pin 3: 1IN+
pin 4: VCC-
pin 5: 2IN+
pin 6: 2IN-
pin 7: 2OUT
pin 8: VCC+

Those voltages look fine with the exception of pin 3 on the lower TL072 (IC1 on the schematic) which is pretty low. I have 3.65V there on my SP. Couple of follow-ups:

• Do you have a signal tester? If not, you could get one HERE or make one (super-simple) from the instructions linked on that page.
• Can you please take voltage readings at both ends of R2 (which feeds 1/2V to pin 3 of IC1) and report them here? See labeled PCB diagram below.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

I do not have a signal tester. Definitely looks easy to build, though I don't have the jack on hand. If we hit a dead-end in troubleshooting, I'll order one. (Thus giving me an excuse optimize shipping and order yet another BYOC pedal!)

What I see on the ends of R2: 1.21v and 4.40v.

Thanks!

Hmm, looks good on the one end and low on the other. Try re-flowing the solder on the low voltage side, though I suspect that won't do anything. In the meantime, I'll do some digging into what else might cause that behavior....

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

OK, I've been kibbitzing with Keith, and here's what he says to try: Pull IC1 out of the socket and take a voltage measurement on the pin 3 slot. If it’s 4.4V (or very close), then the IC is bad. If it still drops to ~1.2V, then there’s a short of some kind or a faulty part in the first few components in the circuit path. Refer to the schematic for which ones those are.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

If I pull IC1 and measure the pin3 slot, I get 2.22v. So that suggests the TL072 is probably OK.

Do you have any hints as to what I might look for to see if any of those early path components are bad or shorted? I probed around a bit, don't see any obvious issues... but I'm kind of just guessing.

Trying to understand the circuit components, this is what I think is going on:

• D11 - reverse polarity protection - if this was backwards, all power would short to ground
• R23, R24 - voltage divider to generate 1/2v - if these were way off or bad, I'd think the voltages I already measured would be much farther off
• C22, C23 - PSU decoupling for v+ and 1/2v - if either or both of these were shorted to ground, I'd think most or all of the circuit wouldn't even power up
• R2 - current-limiting resistor for IC1 pin3
• C1 - signal DC blocking - this has infinite resistance when I put my meter probes across it in resistance checking mode, which is what we want I believe
• R1 - setting signal input impedance (?)

Am I right to think something is "stealing" current from R1, which in turn makes its voltage drop too great?

So I was looking at what connects to 1/2v, which is a number of components, including VR1a/b (the gain pot)... What should I be seeing for resistances between VR1's pins (with VR1 soldered into the circuit)? I see 10k across pins 1 and 2 of VR2 and VR3. So I would expect to see 100k across equivalent pins of VR1, but I'm not seeing that. But maybe with it soldered in place, the DMM is finding a lower resistance route to measure?

Dunno, need some more hand-holding!

Thank you!

p.s. never heard the word "kibbitz" before, had to look that one up.

If you have a 1M resistor, you can try replacing that.

You cannot accurately measure resistor and capacitor in-circuit. They will almost always be in parallel with something else, so you won't get an accurate reading.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

I wouldn't make that conclusion. 2.22V is only about half of what it should be. I'd try replacing that 1M resistor, as Keith suggests.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

So I found I had some 1M through-hole resistors on hand, and replaced the one in question on my SP. Same result, still seeing 2.2v on pin3 of of IC1's socket (without the IC in there).

FWIW, I measured the old resistor after I removed it, and the new resistor before installing it, both were within 50k of 1M.

I also touched up a number of solder joints too, no change on that pin3.

Remove C1. If you are still getting 4.5v on one side of the R2/1M resistor and only 2.2v on the other side, you probably have a small strand of wire or some sort of solder bridge shorting out under the socket, and you should remove the socket.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Just a couple of points of additional information to support Keith's suggestion:

1) The circuit will not pass signal with C1 removed, since it is directly in the input signal path. The point of removing it here is to see if that changes your voltage on the IC side of R2.

2) If you have to remove the IC1 socket, be advised that this is NOT an easy thing to do. It takes time, patience and a deft hand with desoldering tools (a "solder sucker" and/or desoldering braid) to remove a socket that's soldered at 8 separate points! Instead, I would recommend cutting the black plastic body apart with cutting dikes until just the 8 contact pins are left and then desoldering them individually. You'll need to get a replacement, but that's a lot better than damaging the PCB trying to get the socket out in one piece.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Sorry guys, no luck! I did both steps, unfortunately, still seeing only 2.2v on the IC1 pin3 hole.

First I removed C1. Still measured 2.2v at IC1 pin3.

Then I removed the IC1 socket. I just used solder braid to wick up all the solder, and the socket came out cleanly with just a gentle nudge. Still seeing only 2.2v at the pin3 hole.

Try cleaning up the flux with some isopropyl alcohol.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

I spent some time on the board with Kimwipes, Q-tips and rubbing alcohol. It's remarkably clean now, certainly pristine around IC1 and C1. No change though, still at 2.2v on IC1 pin3.

What's next?

Thanks!

Contact nick@buildyourownclone.com

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Is it just me, or is there an unsoldered joint showing in the first pic posted? It's right next to the dual pot and switch - might be one end of R18?

edit: sorry, the first pic of the bottom (solder) side of the board!

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This one?
|
|
V

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Darnit, I literally just got back from dropping my SP off at the post office, otherwise I'd take a look at that. I reviewed my full-resolution pics, I don't have any other pics of the solder-side that show that joint. But pics of the component side, R18 looks soldered on both ends, though that joint doesn't look as clean as it could be (now I wish I'd taken the time to use the DSLR+tripod for taking pics). On the one hand, a simple problem and fix is ideal, but on the other hand, my pride will be damaged substantially if it's simply an overlooked solder joint.

At the risk of further embarrassing myself: a while ago I built two Modulus 86 amplifier modules. When I ordered the parts, I made a mistake and came out one resistor short. So I soldered everything up (except the missing resistor on one board), then waited a week or so to get receive my missing part. In the meantime, I looked over the boards numerous times, looking for any potential errors that might come up when I finally got around to testing them. I got my missing part, soldered it in, and did a test. One module worked perfectly fine, the other was waaaaay quieter than it should be (sound familiar?). I emailed tech support (Tom), first response was "check all the solder connections" (sound familiar?). I grumbled to myself, as I had checked dozens of times waiting for that missing part, but in the spirit of humoring Tom, I did the nteenth check. Sure enough, the board had a connection that didn't get soldered! I soldered it up, and those amp modules have been playing great, pretty much 24/7 since I built them. So I could be looking at another exercise in shame.