Rangefinder

[waaaaaark]

my rangefinder passes dry but no affected signal. Upon probing, I find:

The signal makes it through the 8p switch and I have signal on R3 but nothing on R2.
No signal seems to make it to the transistor or to the boost pot.
The 8p switch seems to behave strangely (only half of the lugs on the back give me signal, but I always get sound on R3)

Thank you

 

[AceHyzer]

A few things:

what transistor are you using and are you 100% sure the pinout is correct?

Are all 3 pins on your pot soldered? It kind of looks like maybe only pin 2 is?

If you could also provide a pic of the other side of the board, that would also be helpful!

 

[PedalBuilder]

my rangefinder passes dry but no affected signal. Upon probing, I find:

The signal makes it through the 8p switch and I have signal on R3 but nothing on R2.
No signal seems to make it to the transistor or to the boost pot.
The 8p switch seems to behave strangely (only half of the lugs on the back give me signal, but I always get sound on R3)

Thank you

It looks like you’re using a Soviet germanium transistor. Which one? Many of the ones that are good for Rangemasters have a different pinout than the footprint on the PCB. If it’s a GT308 or P416, then the red dot marks the emitter, the middle leg is the collector, and the remaining leg is the base. On the PCB footprint, the tab marks the emitter, the middle hole is the base, and the remaining hole is the collector.

 

[waaaaaark]

A few things:

what transistor are you using and are you 100% sure the pinout is correct?

Are all 3 pins on your pot soldered? It kind of looks like maybe only pin 2 is?

If you could also provide a pic of the other side of the board, that would also be helpful!

It’s a 1T308B Soviet Ge transistor from Smallbear and no, I’m not sure of the pinout at all. I have a red mark on one side which I have reason to believe is the emitter.

The pot is soldered on all 3 lugs, there’s just some reflection or something. I’ll take another picture of the back when I’m home.

 

[waaaaaark]

Help me understand something, though, please. Even if I don’t have a transistor connected at all, shouldn’t there be signal at that pin 2’s solder pad?

And could I have fried this transistor by wiring it incorrectly?

 

[PedalBuilder]

It’s a 1T308B Soviet Ge transistor from Smallbear and no, I’m not sure of the pinout at all. I have a red mark on one side which I have reason to believe is the emitter.

As I explained in my earlier post, the red mark designates the emitter. The middle leg is the collector and the remaining leg is the base. The PCB footprint uses a different pinout. Unless you twisted the legs to match the PCB footprint, you will need to switch the base and collector legs, as they are in the wrong pads.

 

[waaaaaark]

As I explained in my earlier post, the red mark designates the emitter. The middle leg is the collector and the remaining leg is the base. The PCB footprint uses a different pinout. Unless you twisted the legs to match the PCB footprint, you will need to switch the base and collector legs, as they are in the wrong pads.

I just twisted the transistor to the configuration you said and the problem still persists

 

[jwin615]

Have you tried to rebias?
Getting -9 at pin 5?
Always having sound on R3 sound like you may have the input shorted to ground

 

[waaaaaark]

Have you tried to rebias?
Getting -9 at pin 5?
Always having sound on R3 sound like you may have the input shorted to ground

what would i do to rebias?

pin 5 is reading 0v