Cosmopolitan Not Working

[angrykoko]

Got my Cosmo built but it's not working as expected.
When turned on I have to max all the pots and the volume is just less than untiy through it.

Volume pot works,  Shape pot changes the tone slightly, fuzz will adjust volume slightly.

Using an audio probe I'm noticing that with the fuzz pot maxed I get no sound at any of the lugs on the pot.  Turn fuzz the other way and I get sound on lug 3 but nothing on 2 or 1.

Also with fuzz maxed there is a volume drop and distortion across D2 (Zenner) & across Q1's Collector and Emitter, turn the fuzz the other way and the volume drop across D2 & Q1 goes away.

Not sure where to look next.

Thanks for any advice in advance.

Mike

[marmaliser]

Are you sure the transistors are in the right way round ?

[angrykoko]

Yeah, that was my first thought too.
Double checked the pinout's and even tried flipping them around for the heck of it.

[angrykoko]

Here's a quick pic. of the board, maybe it's something obvious that I'm overlooking.

[jkokura]

Can you take voltage measurements as well?

Jacob

[pryde]

Also maybe try to re-flow all of the pot solder joints (or others that look suspect)

You might have a faulty ac127 or bc109. Do you have any more to try out?

[angrykoko]

I'll try reflowing the pot solder joints..they were a bit tricky for me.

I don't have a spare bc109 or ac127.. any of these work in those spots  (mpsa18, 2n3904, 2n5089 & NTE159 (which the person at the supply store told me was a direct match for 2n2907)

Some voltage readings with all pots full right (full on).

BS170 (Q1)
S = ~270mv
G = 2.35 v
D = 4.56 v

BC109 (Q2)
E = 4.83 v
B = 4.81 v
C = 4.81 v

AC127 (Q3)
E = 4.81 v
B = 4.82 v
C = 4.82 v

Zenner
Sripe side = 2.34v
Non strip = 268.1 mv

Thanks for the help.

[angrykoko]

Ok.. figured it out...  really embarrassing.

Long version of the story; I must have drilled the holes for the pots in the enclosure too close to the top.. I had to do some "extra" trimming of the enclosure and the pcb to get it in (hind side.. I should have just bent the  leads on the pots a little).

Anyway, in my effort to trim the pcb.. I trimmed too far on both sides (the 45 deg angles) and severed the upper ground plane from the lower. 

Tested with a temp jumper and it got louder, had some fuzz (although not as much as I had expected).

What a bonehead move.

[saxoftenest]

I did the exact same thing with my first Cosmo build.