Obsidian not working, I need help

[Marcos - Munky]

I tried to build the newer version of the Obsidian Overdrive, but I didn't got it to work. I checked the pinouts and they are correct. I just get a very weak and low sound when the effect is on. Here are the voltages that I got from the transistors.

Battery:9.33V
Q1
C:9.33V
B:3.07V
E:3.93V
Q2
C:1.05V
B:1.68V
E:1.03V
Q3
C:4.03V
B:1.96V
E:0.70V
Q4
C:3.99V
B:2.01V
E:1.43V

Anybody that built it could post the correct voltages, or somebody that can find the problem in the voltages can tell me what's wrong? Here is the schematic that I used: www.geocities.com/diygescorp/obsidian.gif

[Marcos - Munky]

:?:  :?:  :?:

[RDV]

I'm confused, I thought that this was the one you already had built.

I've got the voltage values for this at home, but haven't been there long enough to help. Hurricanes are taking all of my time.

If you do a search I'd be willing to bet that there are more than a couple of topics containing voltages for this circuit.

RDV

[spongebob]

The collector voltage of Q2 is too low, should be at least 4-5 volt, I think... check the resistor at the collector of Q2, maybe you accidently used a larger value?

[Marcos - Munky]

Ibuilt the Obsidian, but in another version. This time I tried the last version, which I put the link in te first post of the thread. The first one that I built sounds amazing, but this one don't work. I was thinking that the problem is the Q2. I will check the resistor again, but I believe it's the correct one. But I will try to lower the value of the resistor to see what I get.

[RDV]

I get it now, this is the one with a Blackfire stage in front. I haven't tried it.

RDV

[Marcos - Munky]

Yeah, it's this one. I didn't tried to mess with the voltages of Q2 yet. I need to get what voltage? Something like 4V in the C?

[Marcos - Munky]

I dropped the resistor in Q2's C, and now I got sound, but I don't like it. I will try a audio probe. If I don't get a better sound, I will stay with the old Obsidian that I have.

[RDV]

Which transistors are you using? If you have a spare you might want to try another one at Q2.

RDV

[Marcos - Munky]

I'm using 2N5089s. I tried another in Q2, same results.

[spongebob]

If the collector resistor is ok, check all other components around Q2: the 10k emitter resistor, the emitter bypass cap, the resistor at the base of Q2, etc...

I used a different transistor (BC549) for my build and it worked perfectly without any changes, so since you are using the original transistor there must be something wrong with your components or wiring! Don't give up yet, the Obsidian is really worth it!

[Marcos - Munky]

Did you built the same version as the schematic that I posted? Everything is OK with the parts, the problem is the transistors. I will try to change all for some BC547 that I have here.

[spongebob]

Yes, I used the same schematic as you, I could not get the MOSFETs at that time.

[Marcos - Munky]

I changed the transistors to BC549Bs, and got a weeker sound. Maybe the circuit needs more gain. I will try with some BC547Cs.

[Marcos - Munky]

Sorry for the delay. I tried the BC547 transistors in it, and it didn't worked. Then here is what I did. I removed the transistors (since I knew that they wasn't the problem), the pots, jacks and the swicth, and threw everything in the garbage. Then I got another board, another caps and another resistors, redid the effect with the 2N5089s that I used in the first time, and now it's working great. Just a little noisy, but I can live with this. I will put it in a enclosure and take a photo of it, I will try to do it in this weekend.

[petemoore]

I tried to build the newer version of the Obsidian Overdrive, but I didn't got it to work. I checked the pinouts and they are correct. I just get a very weak and low sound when the effect is on. Here are the voltages that I got from the transistors.

Battery:9.33V >>>good
Q1
C:9.33V
B:3.07V
E:3.93V
 >>>this one the emitter is higher than the base, I think this is a problem, what does the audio probe say?
Q2
C:1.05V
B:1.68V
E:1.03V
 >>>Collector lower than the base...
Q3
C:4.03V
B:1.96V
E:0.70V
 ...This one should be working
Q4
C:3.99V
B:2.01V
E:1.43V
 >>>Emitter seems high...I don't know really how it's used in this circuit or what the operating parameter guidelines are for that tranny...
Anybody that built it could post the correct voltages, or somebody that can find the problem in the voltages can tell me what's wrong? Here is the schematic that I used: www.geocities.com/diygescorp/obsidian.gif

[Marcos - Munky]

Now I think that the voltages are correct, since it's working fine in the new board. But thanks for the info.