Hi guys. I just spent half an hour writing up a nice build report / tech help problem that suddenly disappeared. So this one will be shorter.
Just finished the giant hogweed by David. Has some really cool sounds, but I'm having a problem with the volume levels. When the octaves switch is off, I barely reach unity. When I turn the octaves switch on, I get a big jump in volume. The only snafu I had building this was with T7. I used a BC549, but I had it soldered in the wrong direction. So I attempted to desolder it (huge disaster) and I eventually wound up resoldering a new BC549 via point to point using the schematic (see pics).
(http://i1033.photobucket.com/albums/a420/TGP39/image.jpg5_zpsm1uxnfkq.jpg) (http://s1033.photobucket.com/user/TGP39/media/image.jpg5_zpsm1uxnfkq.jpg.html)
Here are the voltages I took.
t1 e-156mv, b-737mv, c-2.1v
T2 e-1.51v, b-2.1v, c-7.9v
T3 d-5.8v, g-2.53v, s-730mv
T4 e-440mv, b-355mv, c-9.4v
T5 e-0, b-348mv, c-350mv
T6 e-0, b-335mv, c-350mv
T7 e-1.13v, b-1.63v, c-6.9v
U1 1 2 3 4 5 6 7 8 (in volts)
8.8 6.6 6.5 0 0 .175 9.5 6.6
U2 1 2 3 4 5 6 7 8 (in volts)
4.7 4.7 4.7 0 4.3 1.4 4.7 9.5
U1 is LM308n, U2 is TL072
supply voltage is 9.66 volts
(http://i1033.photobucket.com/albums/a420/TGP39/image.jpg1_zpsjd5ftnkz.jpg) (http://s1033.photobucket.com/user/TGP39/media/image.jpg1_zpsjd5ftnkz.jpg.html)
I will post more pictures. Any help is greatly appreciated. I have the build on my workbench so I can take any other readings if needed. Thanks guys.
Steve.
solder side pics.....
(http://i1033.photobucket.com/albums/a420/TGP39/image.jpg2_zpsokqjincq.jpg) (http://s1033.photobucket.com/user/TGP39/media/image.jpg2_zpsokqjincq.jpg.html)
(http://i1033.photobucket.com/albums/a420/TGP39/image.jpg1_zpsou3bakwy.jpg) (http://s1033.photobucket.com/user/TGP39/media/image.jpg1_zpsou3bakwy.jpg.html)
The voltage for the collector of T7 looks weird.
Not sue for e and b but c should be around 5V for T7
pin 6 on the Tl072 looks too low.
It should be at half supply normally but I will need to check the voltages this evening when I get home.
I suspect that there is something weird around T7. can you try to audio probe your signal after T7? It should be a bit over unity, maybe twice as loud, in any case not less than unity.
If nothing helps, I will send you another board. It's my fault you soldered the transistor in reverse in the first place ...
Hi David. I will audio probe around T7 when I get a chance today. Thank you for the help. Honestly, it's not your fault. I should have looked at the schematic before soldering all the transistors. I really appreciate it though. Does my T7 point to point job look correct? I double checked the schematic and I thought that would do the trick. Thanks again.
Steve.
It's not easy to see but it seems like you soldered the collector to the junction of R13/R32/C18 instead of the junction of R32/R29.
the best spot would be here :
(http://i1277.photobucket.com/albums/y492/drolobucket/2015-03-20%2012_06_17-Pale%20Moon.png)
I'll try that. Should I solder it so that R29 and r32 have a solder bridge between them?
Steve.
they are already connected together. You can connect the collector to either resistor on the spot shown above
Ok. I understand now. Will give it a try.
Steve.
Hi David. I repositioned the collector as you mentioned above. My new voltages for T7 are c=5.55 , b=1.35 and e=0.84. I'm going to test and see if this did the trick.
Thank you for your help. Steve.
Well David, your suggestion about re-routing T7 worked! After looking at the schematic again, I have no freakin clue why it worked. Lol, but it worked. I am going to test everything later today, but I think this did the trick. Thank you for your help David.
Steve.
glad you were able to sort it out