Simulcast Issue—Very low volume when engaged. Transistor issue?

[farwest1]

EDIT: I resolved this issue by installing a different Ge Russian transistor. But now I have a different issue—started a separate thread for it. Don't know how to delete this thread.

I just completed a Simulcast that I'm really excited about. But when I engage the pedal, I only get a low volume, fairly clean tone.

If I flip through the three positions of the toggle, the sound gets increasingly louder and maybe slightly more dirty. But even at top volume it's not quite as loud as with the pedal off and in bypass.

Thoughts?

Could it be a germanium transistor issue? I installed a Russian transistor (from Small Bear) with a weird pinout. I checked the pinout online and *think* it's right—what I found online said it's probably ECB instead of CBE. But that could be wrong.

Also, if the transistor was bad, could that result in very low volume?

 

[twebb6778]

Did you socket the transistor? Try flipping it around and see what the output is like.

If you upload some pictures of the board we can take a look at what's going on.

 

[farwest1]

Yup, it's socketed. You mean test out different pinout arrangements?

Does it seem like that might be a source of low volume?

I can post pics tomorrow.

 

[twebb6778]

Yep, swap the pinouts and see what happens. It could be the issue, but could just as easily be something else.

Do you have an audio probe? This will help you pinpoint exactly where the issue is.

 

[farwest1]

So I just swapped out the Russian transistor for one from a Tone Bender MKII I built (a Colorsound TB Pro MK II "Flat Hat".) It has a normal pinout.

Now, when I play the Simulcast with the TB MKII, every setting is the normal volume, but super-starved and velcroey. Each note just fades within seconds. Sounds horrible (but normal volume.)

Is that normal? I think the Tone Bender transistors are intentionally leaky?

 

[zgrav]

Check the voltages at the transistor legs and see what you are getting.

 

[farwest1]

So I figured out the pin out issue with the Russian Ge transistor. But now I get a very loud, constant squeal behind the course signal. When I’m playing it sounds great, but when I stop playing the squeal goes nuts. Sounds like feedback.

The tone of the squeal-noise changes when I adjust the high cut and low cut knobs. I can only make it go away by dialing down high cut and low cut almost to zero.

any thoughts? Do I just need a different type of transistor?

 

[Nostradoomus]

Post some pictures, top and bottom of your board.

 

[farwest1]

 

[farwest1]

 

[zgrav]

Looks like some challenging parts placements with the 1/4 watt resistors and a couple of your caps. you need to take a good look around those leads to see if there any that are touching other metal.

you may also need to pull the pcb out of the case and post a picture of the other side. you need to check that side anyway for cold solder connections and things that might be shorting out. also see if the wires going to the footswitch might be shorting out against the nearby resistors.

 

[farwest1]

Before I pull everything out, any thoughts on what could cause that squeal? The pedal works like normal except the squeal/feedback is constant under the guitar sound. Could it be a faulty transistor, or some problem with power filtering?

I’ve heard that some Fuzz Faces have a similar problem. The squeal appears to mainly come when I dial the Gain Cut knob up above 9 o clock.

 

[farwest1]

 

[farwest1]

 

[zgrav]

No specific idea about the squeal, except that you may be getting some wrong values in the circuit due to things touching that shouldn't be. You may also have some questionable solder connections from some parts being under tension on the board due to squeezing them in.

Others on the board may have suggestions though.