big muff triangle debug help needed please, markm's layout

[makaze808]

Hi there. I have built a big muff using markm's schematic  for a triangle muff in the gallery,  the only parts subs were 1.1m drop down (2*2.2m in parallel) and a 3.3k sub for the 3.6k resistor. I socketed all trannies (2n5088g) and diodes.

the voltages are

q1 c=4.5     b=0.75      e=0.17
q2 c=1.3     b=0.72      e=0.1
q3 c=4.1     b=0.7       e=0.1
q4 c=9.2     b=0.2       e=0

I am getting no sound at all, not a whisper,  when the effect is engaged, bypass is working fine.

This is the 2nd build of this schematic with identical results. Thanks for any help, cheers Woz.

[makaze808]

http://www.aronnelson.com/gallery/main.php/v/MarkMs-Gallery/album15/album76/BigMuff_TRI_LAYOUT_001.gif.html

[JOHNO]

The voltages on Q2 and 4 are not correct. Check for shorts, incorrect resistors, transistor orientation.

[petemoore]

q1 c=4.5     b=0.75      e=0.17
  collector in the middle of the PS rails, base is at least one B/E diode drop above emitter [E near ground]...fine bias on this one.
q2 c=1.3     b=0.72      e=0.1
  There's no room for this one to swing toward - [gnd.], test R value between Q2C and V+.
q3 c=4.1     b=0.7       e=0.1
This one has nice bias on it.
q4 c=9.2     b=0.2       e=0
This one looks as though it's 'too directly' connected to V+, measure Q4CResistor to V+. Also I'm not sure why the Base isn't one B/E diode drop above emitter, perhaps that will swing into place when the collector comes down, but measure the base bias resistors, verify where they are going.
  Q4 Does indicate at least 9.2v on the battery, that's misbiased but important because it tells what %age of PS  all the pins are [iow, you should include the measured V+ reading with bias notes].

[makaze808]

Thanks Peter, did as requested. The fact I had 2 nice biases gave me a good shot of adrenalin, much needed.

I'm not sure how to measure resistance on the board as they ALWAYS measure different, i need some of those mouser ones with writing on then. I thought I found a couple wrong ones around q4 so I replaced those. I have a nice sound now very sweet.

q1  c 4.49   b 0.79  e 0.17

q2  c 1.88   b 0.72  e 0.10

q3  c 4.12   b 0.69  e 0.01

q4  c 4.50   b 1.56  e 1.07     

I will re-check q2's neighbours after tea again.

Thanks all.