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Hey gang, it’s been several years since I’ve been on this forum. I’m having a problem with the fuzzy bee (I’ve built several successfully in the past). I’ve attempted all the troubleshooting I can come up with but have not solved my problem. I’m hoping someone here will be able to set me in the right direction to fix the build.
Using an audio probe, I hear the direct signal coming in on R1 and R2 as well as the base of Q1 but I don’t hear the signal anywhere after Q1. I don’t hear anything on the collector side of Q1. I’ve checked power and it seems to be correct throughout the circuit. I’ve swapped out Q1 with another transistor but it makes no difference (transistors were all purchased from Barry).
I’m at a loss on what to check next.
Thanks in advance for your help.
-ScottI’d check R3 what voltages are you getting on Q1 pins check with it in and out of socket
Because you’ve got them socketed you could stick a jumper in Q1 base to collector to bypass the transistor obviously it won’t work as intended but it should let audio through and let you know if that’s your problem area
I’m taking it you’ve reflowed your socket joints
Everything that I can see looks to be the correct value and orientation those transistors don’t look like any I’ve seen in Barry’s shop what are they? They look like Motorola are they definitely PNP can’t find a datasheet
I was mistaken about where I got the transistors, these came from smallbear. I have a few more sets sitting around to swap in. I’m not sure I’m reading the pcb correctly. When looking at Q1 for instance, my assumption is that the small tab on the pcb stencil indicates the emitter (it appears to be going to R4). Is that correct?
I’m using a battery (currently reading 8.7v). I get -8.7 on pin 8 of the charge pump, I get the same at R3. With Q1 removed, I get -1.5 on the base and nothing on either side. If I put Q1 in and measure I get virtually nothing even on base.
Is it possible to “mess up” the transistors by getting the pinout incorrect? Is it harmful to remove or insert the transistor when there is power being supplied? Thus far, I’ve been unplugging the battery to swap or/remove the transistors.
I have not reflowed the sockets yet, but I will asap.
Thanks for the quick responses.
-Scott
With Q1 out of socket your base voltage is correct and you wouldn’t get anything on the collector and emitter
Base voltage comes from the voltage divider R1 and 2
As you’ll know calculation is power in multiplied by resistor to ground R1 divided by R1 and R2 value in your case 8.7 x 100 / 570 = 1.52v
So you know that’s all good
Check your socket pins don’t have continuity and make sure you don’t have any microscopic bridges anywhere even a wisp of solder can cause problems
It appears that once you put your transistor in your problems begin it being an active device it may only cause a bridge when its connected in circuit, so it may not necessarily be a faulty transistor do you have a transistor tester
You are correct the tab does indicate the emitter and connects to R4 I wouldn’t think you’d damage the transistor if it was in the wrong way around it just wouldn’t conduct correctly
If those are germanium BJTs, the leakage must be very close to zero in order for voltage measured biasing to work well. Most Ge BJTs have some leakage to them and the Burns Buzz Around fuzz circuit needs Q2 to have some leakage to get “that sound”. I’ve built a few of these circuits and always got the best results when the gain of each BJT is greater than the BJT before it and set the bias by ear. I used the following formula the up-cascading gains on the BJTs:
Q1 Gain: 40 to 60. Q2 Gain: 70 to 90. Q3 Gain: 110 to 140
And as Billy points out, socketed trannies can be problematic if they do not seat firmly. (Strong emphasis on “firmly”.)
Good luck!
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