Tube Scr3eamer Woes please help

[Hydesg]

hi guys.
spent 12 hours striaght soldering my tube screamer
without the pcb
i soldered everything on a perfboard

now, i guess i soldered every thing correctly
but theres no output at all
no sound

checked the IC voltages, correct
but when i check the voltages on Q1 n Q2
they were wrong

for Q1n Q2
the  voltages should be

E-3.0
B-3.5
C-8.8

but what ive got is
E-8.9
B-8.9
C-8.9

i was wondering if there was anything wrong somewhere
ive checked the connections around the transistors
they dont seem to be wrong

im using a npn 2sc1815 transter
and jrc4558d ic opamp

schematics can be found here








guys please help me solve this

i am having a headache now
:shock:

[petemoore]

Look for a miswire or wr value Resistor around the transistor and check it's pinout.

[Hydesg]

anyone out there knows of a way
or please provide me some voltage to check with

[petemoore]

RG's site has the excellent bias info.
 If you're getting supply voltage at all three transistor pins, pull the transistor [if socketted] and test for continuity between the E, B, and C pin sockets. DMM set to beep mode, even with the tranny's in you should not have continuity between any of either of the Q's pins.

[Hydesg]

hi
ive checked the voltages at the base and emiter before entering the trans
they were 4.6~


checked the continuity
nothing wrong

[Fret Wire]

Did you double check that you don't have one, and/or both of Q1 & Q2 pinout's reversed?

[Ed G.]

I'm thinking the transistors were both put in backwards, and are acting as a 'switch' to let the supply voltage pass through.

[Joe Davisson]

The pinout for those transistors are different than most (flat side up):

1. base
2. collector
3. emitter

-Joe

[Hydesg]

i tot it's
emiter
collector
base?

or is it

1. base
2. collector
3. emitter


im confused

it's written

c1815
w 10

on the transistor chip itself

[Hydesg]

hi
ive changed the orientation of the chip
now
theres no voltage at Emiter

base reads 2.93 and collector reads 8.8

is there anything wrong?

[R.G.]

when i check the voltages on Q1 n Q2
they were wrong
...
but what ive got is
E-8.9
B-8.9
C-8.9

i was wondering if there was anything wrong somewhere
ive checked the connections around the transistors
they dont seem to be wrong

They are. It's likely that there is no connection to power ground from the emitters. I think that if you remove the battery power and measure DC resistance from the emitter pin to ground you'll find that it's open.

[Hydesg]

hey
guys!
thank you very much for your help

it works!
the main problem lies with the transistor

the transistor pin out is different from the schematic
thats why it didnt work!

hey

i am so happy

[Mark Hammer]

The magic and mystery of transistors.

Transistor-based circuits are so much easier to perf than chip-based circuits, but the odds of installing a transistor with incorrect pinout assumptions seem to always be *at least* 67%.  :wink:

If you are ever using a transistor that is anything beyond a 2N3904/3906 or a 2N5088, do yourself a favour and verify the pinouts.  We've all grown up believing that the pins are laid out E-B-C on everything, but so many devices are anything but that.

A DMM with hfe testing is indispensable for setting these matters straight.  Even if you can't read the part number, you can keep rotating the transistor, and swapping between PNP and NPN until you get a sensible hfe reading.  Once you get that the labels in the meter's transistor socket will tell you the correct pinout.  You CAN get hold of device datasheets on line, but I understand that not everyone can find everything they need as easily as they'd like and not every manufacturer observes the same pinout sometimes.  If you can't read the numbers or aren't sure what to do with the suffix, that makes it even handier to just skip the datasheets and go to the meter.

[Fret Wire]

Congratulations!   Well, how does it sound?

BTW, so true, Mark. Always better to double check pinouts before assembling. One less thing to worry about if the effect doesn't fire right up.