[Billy]

Nice clean looking build Chris that’s some excellent work with some great mod ideas

[Billy]

D7 is indeed a polarity protection diode a 1N4001 is fine for that

With filters I’ve changed or added switches to I found that it’s not too noticable making small changes to the capacitor value so it’s always a good idea to socket as you are to get precisely what you want

Again as you say bigger value more low end and visa versa

Here’s a very useful circuit guide from kitrae

http://www.kitrae.net/music/big_muff_guts.html

[Billy]

You want to set the drain pins to 5v initially using their trimmers

With regard to pulling pads off you can solder on either side of the pcb if it’s drive pot lug 1 with the little 1 silkscreened next to it that goes to ground so you can directly wire the pot lug to any ground point

As you can see it’s wired as a voltage divider – circuit in to lug 3 out lug 2 and 1 to ground so like a volume pot it’ll control how much signal goes to the output and how much gets dumped to ground depending on the pot rotation if lug 1 has a poor connection it would act weird easy enough to continuity check with your meter placing one probe to the actual pot lug ( not the wire) the other to ground

The schematic shows connections with the drive pot lug 3 is connected to C4 lug 2 to R7 and 1 to ground

So before you change anything I’d check continuity on them first to see if theres a problem following the changes you made

 

[Billy]

Post some nice clear pictures of both sides of the board and your offboard wiring to jacks 3PDT etc so it can be traced Caspar

Have you actually pulled solder pads off the pcb

We’d need to see it to advise

[Billy]

You want 24 gauge Tim

Which country are you in

I’m in agreement pre bonded stranded wire is best with the insulation pushed flush to the board as mentioned stick your wire through then heat the bare end for a couple of seconds at the same time pushing the other side flush to the board the insulation becomes sticky and adheres to the pcb a little helping secure it

 

 

[Billy]

That weather in the States looks brutal I hope it all gets better soon and everybody stays safe and well

 

[Billy]

Fantastic! you’re a man and a half as we say over here Ray meaning you’re a generous all round good chap

What a great thing to do for another very generous man in oor Barry

[Billy]

You’re biasing the input of the BBD, even the same type of IC may bias slightly differently

If you don’t bias it correctly you may get distorted output or no output at all, internally it’s a number of stages, connected capacitors and switching transistors / FETs which require correct DC biasing to work as intended like a fuzz face if you bias the transistor incorrectly you’ll get sputtering output you may have a greater range but you’re trying to achieve different  outputs distorted or as clean as possible

Obviously it’s a tad more complex than that you’ve other things to consider like externally connected components clock frequency etc but it’s basically the same thing to get it to work the way you want

Here’s an article from the great Mark Hammer page 4 for biasing info

https://www.premierguitar.com/articles/25035-behind-the-bucket-brigade

 

 

[Billy]

No if you haven’t populated the board simply don’t solder the end of C1 that adjoins R1

Tack pot lug 3 to R1 side that doesn’t go to ground then lug 1 directly to C1s lifted leg

By not soldering that leg of C1 you’re effectively breaking the trace without actually breaking it you’re just breaking continuity between R1 and C1 where you need to, obviously make sure the lifted C1 leg doesn’t make contact with it’s solder pad

You should still be able to do it on the underside

[Billy]

I would tack it on without the 100R initially just tack your pot lug 3 to the 1M side that isn’t grounded then jumper lugs 1 and 2 and tack lug 1 onto C1 on the solder side of the pcb that way you’ll be able to change or remove it easily if it’s not to your liking

It’s a B100K weirdly enough I just built the other one

[Billy]

I would place it after the 1M pulldown resistor

I’d say it’s more like a pre gain control adjusting input signal the other one has a 100R in series with the pot

[Billy]

You’re correct Dave my mistake  I’m forgetting the original was BC549s I was looking at the build doc not your image so never accounted for them being opposite the silkscreen

It was just to make sure your pin labelling was right for EBC albeit not put across very well by me apologies for adding confusion

Pinout backwards as it should be for 5088s, left to right would be EBC, is that how you noted the voltages

What are Q4 DSG pin voltages with the J113

You will get it going just takes a little time as you know to figure out what’s failing

[Billy]

For a first build that looks excellent John really nice

[Billy]

A 2N3904 won’t be any good it’s a BJT you need a FET for Q4 like the J113 Dave

I think your transistor voltages may be mixed up the 5088 pinout looking at the pcb would be from left to right CBE

They look way off Q2 base is obviously wrong at 152.3v

 

 

 

[Billy]

Jon try increasing the gain pot to 1M that’ll give you more resistance in the negative feedback loop = more gain

[Billy]

Nothing stands out apart from R22 doesn’t look like a 1K it looks like a 1M that would cause problems and T1 is 20K (203 code) albeit that would still work, it would just make it more difficult to get the required voltage on Q4 drain

What are the voltages on Q4 pins

 

[Billy]

Yes should be fine it’s just to provide 5v to pin 1 of the PT2399 the 7805 just puts out much more current in comparison

Obviously pay attention to pinout there are a few confusing pinouts around so use your manufacturer datasheet

[Author]

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