Sabrina Boss OC2 debug

[pastiche]

Hi all, I've been looking at this one I built a while ago and couldn't get to work. Still can't...


I get an earth hum-esque sound
Some audio is passed, all pots have the effect of changing this hums tone slightly.

I've cont. probed between all vero tracks and no continuity except between linked tracks. All cuts are open circuit too. No other solder bridges, well not that I can see anyway.

I'm using 2sk30a's as q1 and q2. From what the text says and based on my data book they are oriented backwards according to the icons on the layout shape ie flat side is nearest to ic1. Is that true?

Found these voltages listed online:


For the just part my readings power on (no input plugged in) appear close/the same.
Except ic1 pin 1 which varies between 0.1 and 8.4v


Any ideas you could offer greatly appreciated

TIA,
Mark

[pastiche]

In the title Sabrina should say Sabro... Sorry Harald.

[anchovie]

You need an audio probe for this one - start at the effect input and work your way to the point where the sound goes screwy.

[duck_arse]

http://pdf.datasheetcatalog.com/datasheet/toshiba/1032.pdf

the datasheet above shows the gate pin in the centre of the package. fets can almost always be used with their nominated drain pin in the source position, ie the source and drain are interchangeable. this would mean, with gate centre, the transistor would work the same, backwards or forwards.

however, the layout shows 2sk30a, and you're using 2sk30a, so wouldn't you just shove em in like in the layout?

this circuit? with no signal, pin1 IC1 should be a little more than half your pin4 voltage on the same ic. find out why it isn't so.

[pastiche]

Thanks for the replies. I'm not sure that schematic is going to be much help without being relabelled. ic1 pin 4 as shown goes to ground?

I've swapped q1 and q2 today but no change in voltages at ic1 at least.

Is somewhere around c9 r11 or r7 a good place to delve? Pin 1 on ic1 seems to flick between 0.1, 1.35 and 8.4v

[duck_arse]

can you post a link to, or an image of, the circuit diagram you are working from, not just the vero and someone else's voltages? without a diagram, I hadda go and look, and the above is what I found, a boss oc2.

nobody likes to revese engineer vero. do they?

[pastiche]

I found this today which has relabelled the ics at least

[duck_arse]

well, I hate to say it, but that new diagram still shows IC1 pin 4 as ground. so neither diagram seems to match that list of voltages. the part numbers don't match either.

we need a new , correct circuit diagram that matches the layout you're using.