YAFF No Sound from Effect, test results included.

[mrmrcoleman]

I have built the YAFF project by Jack Orman (www.muszique.com/lab/yaff.gif), however there is no output whatsoever from the effect.

All the components are exactly the same except I have a BD139 as Q1 and a PN2369 as Q2.

I have tested the voltages at each of the pins and this is what I get.

Q1.
Collector: 3.8 volts.
Base: 0 volts.
Emitter: 0 volts.

Q2.
Collector : 7.4 volts
Base : 3.8 volts
Emitter: 0 volts

I also went through with Craig Ohikubo's Audio Probe and got the following results...

- At the base of Q1, the sound is the normal clean tone, as is to be expected.

- At the collector of Q1 there is white noise.

Everywhere else in the circuit gives nothing, does anybody recognise these what might be happening here?

Thanks in advance for any help.

Mark

[MartyMart]

Make sure the emitters have 100 ohm and 220 ohm resistors, not "k ohm"
Pinout ?
2369 metal can has "tab" at emitter
BD139 - I've never used ?
Normal checks for wiring/solder bridges ...

Marty.

[mrmrcoleman]

Yes, all the resistors are correct. I used my transistor checker to get the correct pins for the 2369, and the project is in a breadboard.

Maybe I should just rebuild the whole thing triple checking as I go, bit of a shame because I was very careful the first time round.

I thought the white noise might be a bit of a clue but nevermind.

My first effect is not going very well!!

Mark

[MartyMart]

Dont panic Mark, first ones quite often dont !!
It's sometimes hard to tell, lots of people post problems
then come back with a "DUH" head slap answer, that it's almost
impossible to guess at !!
I've got a companion fuzz that's just gone dead ... can't work it out
and I've built a TON of working circuits !!
It has to be a bad component, so it's a re-build, which is often
quicker than identifying the part in a small circuit !

Cheers,
Marty.

[amz-fx]

I have built the YAFF project by Jack Orman (www.muszique.com/lab/yaff.gif), however there is no output whatsoever from the effect.

The pinout of the BD139 is often E-C-B which is different from that of the 2369. This is probably where you problem lies.

regards, Jack

[mrmrcoleman]

Thanks for the feedback. I WILL get this working..

Mark