DEBUG: ProCo RAT clone

[Arangonix]

Hi guys,

let's get down to business. I'm building RAT clone for my friend. This is my first pcb project I've built dozens of old school boosters and fuzzes using turret board with great succes, but this modern technology don't like me, I think.

Whats wrong: the RAT is super quiet. With my nearly fully cranked Tweed Deluxe and ES 335 plugged in, the RAT is producing a level of volume typical for normal talking (even with vol and dist knobs fully open), if I turn RAT's knobs below noon, it is just wispering.
Generally, it seems to work "fine", I mean all knobs do what they should, it distorts the signal etc. It sounds fizzy a bit but probably because of lack of volume.

I've built it using pcb I bought online:

https://guitar-electronics.eu/en_US/p/RAT-PCB/125

They even provide a list of parts and schematic.

As for op-amp, I used TL071, FET is 2n5458, as I read they can work with this circuit without modifications. The rest parts are stock.

Here's some voltages (measured with 9V power adapter plugged in):

TL071:

1. 0,14
2. 4,49
3. 2,21
4. 0
5. 0
6. 8,93
7. 4,49
8. 0,14

2n5458:

G 0
S 1,46
D 8,92

All parts (caps, resistors, pots) were checked and all works fine. Op-amp and FET also, I even swapped them with new ones, as I have a bunch of them. I resoldered everything once and built it once again, I checked all traces.

Any ideas?

[11-90-an]

Can you try flipping your JFET around? i.e. 180 degrees...

If that doesn't work, pictures, please... 

[bluebunny]

Since an opamp's purpose in life is to make its inputs the same, there's something going on with pin 3.  And fyi, the pins are counted anti-clockwise (power should be on pin 7).  Post some pictures of your board so we can see if we spot anything amiss.

[POTL]

The reason is quite simple, your board is designed for OP07 or original LM308N, you are using TL071 with a slightly different pinout.
You need to find OP07 or LM308N

[11-90-an]

The reason is quite simple, your board is designed for OP07 or original LM308N, you are using TL071 with a slightly different pinout.
You need to find OP07 or LM308N

Wait... that makes sense... 

[duck_arse]

Can you try flipping your JFET around? i.e. 180 degrees...

If that doesn't work, pictures, please... 

this is bad advice in my book, because the poster will have the datasheet there, showing they have the correct pinout and orientation. however - in this case, the circuit diagram shows a BF245a, which as we all know, has the gate pin on the opposite end to "the FET is 2n5458". but the builders photos will show all when they appear.

and the non-invert pin voltage is being loaded by the meter taking the measure - the out pin matches the inverting pin, so good enough.