Catalinbread SPP Boost not working

[Jack Cripps]

Hi, this is my first time on the forum and unfortunately it involves asking for help! Anyway, the problem is that I have no sound apart from a repetitive buzzing sound when connecting the circuit to the amp, with no guitar coming through at all, I've double checked layout and orientation of caps and diodes unless something on the layout is incorrectly orientated which i find hard to believe, I've resoldered all joints to prevent cold solders, and ive also replaced the BS170. Also the voltage at Drain is 9v which is incorrect according to the other discussions I've read it should be around 5v.

I just need someone with greater experience than I to have a think about what could be wrong. I can upload pictures and component lists if necessary.

Cheers, Jack

[IvIark]

Post the other pin voltages Jack to see if they throw up any more clues, and yes a high res front and back pic of the board would definitely be useful too

[Jack Cripps]

The gate voltage (I think that's Centre pin) is measuring 0.14 v and the source is coming up as 0 v, both measured from transistor to ground.

Cheers, jack

[Jack Cripps]

There's the back of the board.

Cheers, jack

[Yehudi]

No expert here, but isn't there a solder bridge between the 3rd and 4th row? maybe you could start by making sure there's no solder making contact between the rows, knife the gaps after each build, so this is one less thing on your mind when you have to debug your build. As I said I'm no expert on this, I don't even know this layout, just my opinion by looking at the pics. Cheers

[Jack Cripps]

Think I may have found the problem, in place of the 100k resistor I believe there is a 10k (code brown black orange) would this explain the issue at all? strange since i ordered a 100k but there could have been a handling error I suppose. I've scored the tracks and there are no solder bridges, but I will remember to do this for future builds, so thanks for the tip.
Cheers, Jack

[Jack Cripps]

Still no luck, replaced resistor and transistor showing correct pin voltages, but no sound coming through, just electronic buzzing the same as when you touch your amp guitar lead to a metal surface. Any ideas?

[induction]

Sounds like a grounding problem.

Can you take a few more pictures of the component side and offboard wiring? It's hard to make out details in the picture. A few different angles would be helpful.

A few questions for you:
- Is the diode oriented correctly?
- Is the 470uF oriented correctly?
- Are the jacks wired correctly
- Why is the 10M resistor so much smaller than the other resistors?
- Why is there a big solder blob on the 47p leg?
- Does the led light up?
- Does the boost knob have any effect on the hum?

Some of your component legs should be trimmed to avoid shorting.

[Jack Cripps]

[Jack Cripps]

I soldered all grounds together and then that to the negative battery terminal, and just connected in/out to respective jacks. So far as I can tell the electrolytics are correctly orientated and I have no idea why that resistor is so small, but I'm pretty sure it measures 10M on the multimeter (100 on 2000k setting, correct me if I'm wrong, this is all new to me). The solder blob is because the legs of that specific cap were really short so i had to solder a resistor leg to it to make it long enough.

From the layout the diode is correctly orientated, however it is a 500mW 9v1 compared to the 1W 9v1 that is specified, I'm not sure if that makes a difference or not.

[induction]

I still can't quite tell from the pictures, but it looks like your input jack might be wired incorrectly.

If I had to guess, I'd say that the lug on the right in your last picture is for ground (shaft), the one in the middle is for signal (tip), and the one on the left is for input grounding (ring). I say this because the lug on the right will make direct contact with the enclosure, and the one in the middle looks like it connects to the body of the jack at a lower point (closer to the plug insertion point) than the one on the left. The tip connector is directly behind the ring connector, so geometry dictates that it must connect at a lower spot on the jack body.

Examine the jack closely by eye to see which lug connects with which part. If you can't tell by looking, desolder the wires, insert a patch cable (to disconnect the input grounding tab from the tip connector), and check for continuity between the lugs and the free end of the patch cable.

Once you get it figured out, you might consider grounding the ring lug so that the pedal is silenced when the input jack is empty. Not crucial, but useful sometimes.

[Jack Cripps]

right, swapped the lugs on the jacks and I have it working (kind of) but when I turn the boost up to max and mess with the guitar volume there is a very strange oscillation type sound occurring, and also a bad hiss when the volume on guitar is turned down at any point on the boost knob. Is this due to bad grounding or something, and would it be rectified when its in the case?