Build Your Own Clone Message Board

I started building a Tremolo kit waaaaaaay back in September and i discovered after a few tweaks that when i plug in my guitar and play a bit through it, there is no added tremolo effect, only maybe a small boost. What kinds of things can cause this problem? All of my resistors are placed right, all caps in correct spots and positions, signal has a path it can follow, but none of the tremolo reaches the amp. I will post internal pics in a little bit.

EDIT: Actually, i just retried the pedal, and it cuts about half of my signal when I engage the effect, the LED is on but not flashing, and changing the volume changes the amount of signal coming through while it is engaged.

Definitely post those photos ASAP! Large, in focus, and showing all the wiring and both sides of the circuit board. Someone will be able to help, I'm sure!

Your low frequency oscillator isn't running. This is the bit of the circuit around Q4, a 2N5088 (the transistor up by the LED) with the three large 1uF caps. It is a pretty unusual oscillator and I get the impression it is a bit temperamental. It may just be that Q4 is a bit low on gain and replacing it may fix the problem. Otherwise - usual advice about check all your joints for shorts and opens and maybe re-solder.

There have been some instances of faulty footswitches and the pedal relies on the footswitch to connect the emitter of Q4 to ground which starts the oscillator running. Check your footswitch for continuity, particularly between pins 1 and 2 (top left and centre left, pedal viewed from the back with the jacks away from you). You can even try temporarily shorting those two pins together with a mini crocodile clip test lead (careful - you will need a lead with very small clips) to see if the oscillator runs and the LED blinks.

Also be aware that as far as I can see the oscillator circuit takes a good 10 seconds or so to get started when you first apply power to the pedal.

LED not flashing means your LFO (low frequency oscillator) is not oscillating. Could be a transistor misplacement, could be a cap or resistor in that part of the circuit, can't say until we see pics.

BTW, if it was boosting before and now it's not boosting but rather cutting the signal, and you haven't done anything with the volume knob (assuming it's Rev 2.2 or later), there's a cold joint somewhere else in the volume part of the circuit. All a trem consists of is a volume section and an LFO to ramp it up and down (plus a reverse polarity protection, some PS noise filtering, and a couple other modern niceties).

Tark - the LFO should run as soon as there's power to it, if it's taking that long to get going there's a good chance something else is up...

No matter what is going on with the low frequency oscillator, the amplifier section of the trem should have a gain of around 5. So a signal loss is not normal.

tonedeaf -

My comment about the oscillator perhaps being slow to start is based on a SPICE emulation of the circuit. This only happens when power is first applied to the circuit. In normal use most people probably would not notice because the pedal is powered up when it is plugged in and stays that way until you unplug it. I only mentioned it because it might be misleading during de-bugging which is not normal use.

Here's a quick shot of the component side of the pcb

Sorry dude but pics need to be larger, sharper and better lit to be of any use. It needs to be as if anyone trying to help almost has the pedal in their hands 8 inches from their nose in bright lighting. Clear daylight with no shadows over the PCB is the best. sometimes you can get something usable off a flatbed scanner if it has a decent depth of field.

Anyway I would check your switch wiring - it is very hard to tell given the quality of those pictures but it looks to me as if the last wire to the right (exits the PCB next to the white silkscreened T in Tremolo) does not go to the centre pin on the right of the switch.

Here, a bunch more pictures that are far more detailed

I think I need to start taking pics like that of any of my own builds that aren't working and looking at them myself - you can see so much better than with the naked eye. At least I can, maybe my vision is going in my old age.

Start with the leads on your wiring joints - trim those down, the ones on the footswitch and the in/out jacks make me nervous. I'll have a look at component values tomorrow. The electrolytic caps look correct, and the transistors (assuming they're in the correct locations) look good as well.

I'm not real fond of the purple hook up wire that BYOC provide - it melts way too easily. Anyway here is a tip to making neater wire connections with it.

Use a wire stripper that makes as clean a strip as possible - the 'two bits of sheet steel with V notches and a bolt for a pivot' type tools can be used for wire stripping but they aren't very good.

Set the stripper so that it cuts almost through the insulation but make sure it does not cut any of the wire strands.

With a short length of insulation stripped off, twist the strands neatly together between thumb and finger - you should end up with a tight neat length of twisted strands.

Apply solder and a soldering iron to this stripped section to solder the twisted strands into a solid length of wire.

Then push the solid section through the hole in the switch or PCB.

Apply the soldering iron to the junction of wire and tag or wire and pad then immediately apply the solder to the junction of the iron, wire and tag or pad. If the iron is hot enough this should melt and flow into a perfect joint in under one second. The aim is to produce a good joint without overheating the wire and having the insulation melt back along the wire.

From your pics all the resistors and caps seem to be in the right places. Switch and jack sockets seem wired correctly. Soldering is not great. Can you just check you have the transistors in the right place - two of them are 2N5088 NPN transistors and two are 2N5457 JFETS. Just make sure the 2N5088s are in the 2N5088 positions and the 2N5457s are in the 2N5457 positions on the PCB.

I just checked the transistors, and they are correctly placed, and there seems to be no unintentional connections between wires or solder spots.
However, now the pedal is much more intrusive. When I am playing through it, bypassed, a slight jiggle of the footswitch causes the signal to cut significantly, and the distortion from my amp is gone.

Your soldering of the stomp switch and jacks is very poor. You are clearly not getting good heat transfer from the iron to the lugs of the switch and jacks.

The soldering of the Rate pot's wiper looks cold and solder starved...


The photo is a bit blurry but the soldering of lugs 1, 4, 5 and 8 look cold. Lug 8 looks especially bad...

Yep - follow Tark's advice and get those wires re-stripped and tinned so that the ends don't fray out like that when you insert them into the lugs; then the reflow of all those joints as Stephen mentioned and you should be all fixed up.

When you say that the lugs are cold, do you mean on the switch itself, or on the pcb? The joints all seem to have plenty of solder. Also, should I completely replace the footswitch wire?

Cold lugs - the trouble with the larger metal tags like those on the switch and jack sockets is that they take more heat input from the soldering iron to get up to soldering temperature.

For a good solder joint, not only does the soldering iron have to melt the solder, but it also has to get the two surfaces to be soldered together briefly up to the same temperature as the solder, so that the solder stays molten as it comes in contact with them. If the surfaces being soldered are significantly below the melting temperature of the solder then the iron may melt the solder that is in direct contact with the iron and just deposit it as a blob sitting on the surface of the joint, rather than alloyed with the surfaces. This is what is meant by a 'cold' solder joint.

The other thing that has to happen is that the joint has to be heated for long enough, to a high enough temperature, for the flux component in the cored solder to react with and break through any surface oxide layer on the metals being joined. Jack contacts are often plated with nickel that seems to have a particularly tough oxide layer. It can be difficult to get the flux activated and getting through this surface oxide. With obstinate jack tags I often polish the surface of the tags with a fine file or a glass fibre pencil brush to help get through this oxide layer.

The skill of soldering is knowing how to get the iron in good contact with the joint for just long enough to get everything up to temperature and then holding it for long enough for the flux to get through the surface oxides and then the molten solder to flow out and alloy with the joint surfaces. The other thing that can cause cold joints is any movement, particularly between the two surfaces being joined, as the solder cools.

It is up to you whether you replace the footswitch wire but is probably the only way to neaten it up. A word of caution though - the glue and plastic parts of the footswitches do seem to be a bit heat sensitive and over heating the tags on the switch can apparently cause it to fail. You could practice getting neat twisted and tinned ends on the wire (pre soldering the ends of things like wires is known as tinning) with the excess wire you have over and perhaps practice getting good smooth shiny joints on the jack sockets first before you attempt the switch again.

Good luck!

Okay, I'll work on it after I get home from school.