tycho octavia doesnt work

Started by sir ladderhole, January 18, 2006, 03:53:46 PM

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sir ladderhole

Alright, after lots of frustration and burned fingers, my tycho octavia does not work. I built the positive ground version from justin philpotts site ( http://www.geocities.com/j4_student/tychobrahe.gif ). I built the project on perfboard and made no substitutions whatsoever. I can get pictures of the board if they would help. I already checked the transistor orientations.
At first, the pedal worked a little bit; it had a very ugly fuzz sound to it but after a few minutes it stopped. There was no noticible octave effect. Now, however, the pedal produces no sound. Occasionally it will make a fart sound - think of the sound little kids make with their lips, also the same as the motorboat sound. I can try to record this if it would help, although it only happens once in awhile.
The battery i am using is brand new - according to my voltmeter, its 9.03 volts. The voltages of each transistor, going from left to right on the schematic:

Q1
C = -8.62
B = -8.10
E = -6.8
Q2
C = -7.3??
B = -6.73
E = -9.02
Q3
C = -7.6??
B = -7.6??
E = -9.02

The numbers with the question marks next to them constantly fell asi  measured them - they started around 8.0 and fell continuously, one got down to 4 and was still falling, so i just picked any random value that happened to show up on the voltmeter. The voltages of both ends of both diodes was zero.
This is my first build. I have minimal electronics experience so i am sorry if there is a very simple problem. I have spent an hour or so last night and another hour today - I was hoping to figur ethe problem out myself but i have obviously overlooked it. Any help would be appreciated. Thanks,
Chris

jmusser

One thing you need to look at thaat can go wrong, is the transformer orientation. This transformer is a step down type, but because of the low current, it is turned around backwards so that the primary is actually the output side, used as a step up.
Homer: "Mr. Burns, you're the richest man I know"            Mr. Burns: Yes Homer It's true... but I'd give it all up today, for a little more".

sir ladderhole

Yeah, i do have the primary side going towards the output. (Unless the primary side is not the side labeled with a p??)

sir ladderhole

alright, so i fixed so it works (dont know what i did - poked around with a soldering iron a bit)  but it definitely doesnt sound as nasty as the sound clips i heard on justin philpotts site and on GGG. heres a clip of how mine sounds
http://s37.yousendit.com/d.aspx?id=2LR66OVDEUQQK1D5ABFPY4CP1D

Q1
C = -5.99
B = -4.63
E = -1.80

Q2
C = -1.28
B = -1.80
E = -8.93

Q3
C = -0.63
B = -1.27
E = -7.42

the diodes are still 0

petemoore

  Voltages look wierd to me...
Q1
C = -5.99 [might be passable except the base is very close
B = -4.63
E = -1.80[ kinda high?

Q2
C = -1.28 [X lower than the base
B = -1.80 [
E = -8.93  {This emitter is very higher than the other two pins<

Q3
C = -0.63 [very low, not much coming through here
B = -1.27 [
E = -7.42 Again real high

the diodes are still 0
  But the circuit is 'wierd' also, there are probably 'target' voltages to look for in the circuit...I'm no octave expert, I know one [2nd?] of these Q's is used to split the signal...I'd need to look at the schematic to ramble more questions than answers...
  One thing to look for is the PNP/NPN thing, being certain that your'e power supply is congruent and that your'e using the right type for Q1 Q2, and Q3.
  Also worthy of special notice is that theyr'e not all 'upside up' check out the arrows inside the circles [on the schematic] that indicate transistor polarity AND pinout, one IIRC has it's collector going to the top power rail...
  When placing the transistors and also when taking voltage readings, the pinout is 'upside down', part of the time, know when.
Convention creates following, following creates convention.

sir ladderhole

the transistor pin orientations are all correct, ive checked many times. i found target voltages for the negative ground version of the pedal, not sure if they should be the same but here is the schematic http://www.generalguitargadgets.com/diagrams/toctsc.gif and the voltages it should be are here http://www.generalguitargadgets.com/index.php?option=com_wrapper&wrap=toct_inst down at the bottom. i just dont know what i did wrong.

petemoore

  I use the 'ol crap shoot method, most of which is outlined in 'what to do when it doesn't work.
  I measure *resistances of resistors, continuities between stranded wires/solder/leads/socketlugs etc.
  MEasureing resistors in circuit...larger value reading means wrong resistor, smaller value than schematic calls for means....skip it, [after cursory observation about math...ie "Is there a possible other path?] do math for alternate path through the circuit and across the R, pull one end of the resistor and measure its actual resistance. I never much find bad resistor, correct connections to it are a different tale.
  Count connections at each node on the schematic, and the board...compare, note orientations of component connections from node points.
Convention creates following, following creates convention.