Sex Drive debug

[Philster]

Hi Folks
Built a Sexdrive booster this morning but cannot get any sound out of it.....it's this one.

http://tagboardeffects.blogspot.co.uk/2017/01/durham-sex-drive.html

Have knifed the board numerous times between the tracks and have superchecked that there are no unwanted links. Also been over the layout many times - hopefully someone can see something obvious :)

Voltages on the IC are:
1 - 1.2v
2 - 6.9v
3 - 4.3v
6 - 8.4v
7 - 8.4v
8 - 9v

I get signal on bypass so my switch wiring is fine (using an old build carcass to test it). I get one LED lighting up all the time when it hard mode. If anyone can see anything obvious I'd be grateful!

Cheers
Phil

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[Marbles]

Only had a quick glance, but could you check the cut underneath the IC?




It doesn't seem to be complete

[mug]

Hi there,
here's what I see on a quick glance:
- the diode seems to be bridged on the solder side directly where 9V comes in
- the solder where 9V comes in looks strange (but since you have voltage at the chip it's probably fine)
- there's one cut under the IC (between 4 and 5) that looks suspicious - are you sure the track is cut completely?

EDIT: ah, Marbles was quicker... but that's the cut I was talking about, too

[Philster]

Thanks Gents - yes, the cuts are all clean. I shine a torch from behind the board to see if there are any bridges or blobs left - works really well. I did bridge the diode where the 9V comes in as a last try to see if that was an issue - it was bringing the 9V down to 8.4 so wanted to check it wasn't starving the circuit (no it wasn't!)
I'm a bit frustrated as I've check every component about ten times now and everything seems to be correctly placed and of correct value. It's not exactly a huge board ! I was just wondering if it has been truly verified yet? Probably a boo-boo on my part, though ;)

[ξεναγος νεκροπολης]

i agree with Marbles...please check it with a multimeter or just cut it with a razor or something. that, and two more i can see... the one just above pin1 of the ic, and the one just at the right of pin one, under the ic. also i would apply more solder on pin8. if we're right, that could have burned your ic...

[Philster]

Many thanks Gents - have done as you suggested and now have sound! I've redone a few joints and removed the bridge on the power diode. Voltages on the IC are..
1. 4v
2. 4.1v
3. 3.8v
4. 0
5. 4v
6. 4.3v
7. 4.3v
8. 8.3v

Treble control works, volume works but can't get more than parity with volume and gain on full. Slight difference in volume switching between compression modes but no noticeable squish and definitely no overdrive - not sure how much drive this circuit gives?
So I'm close not totally there - any ideas where I should be looking? I switched out the IC and it didn't make any difference.
Cheers
Phil

[Philster]

Ok, found one more tiny bridge and now works great -  thanks again to you all for your assistance.
I've learned one thing - my eyesight isn't as good as it was ........

Cheers
Phil

[mug]

Congrats!
How does it sound? I don't think its meant to give a lot of drive...

[Philster]

I'm very happy with it - lots of volume boost, a pleasant amount of "hair" from the drive and the treble control is more of a presence control, very sweet. The two compression settings are very useful too - I wanted to have a solo boost that gave a little extra gain and squish so I don't have to hit a solo boost AND another drive in one go. This should work out perfect - got a rehearsal tomorrow night so I can try it out at volume and see if I'm happy.
Thanks again for your advice, can't believe I made such rookie mistakes! Time to get myself some reading glasses for up-close work, I think
Cheers
Phil