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Old 10th February 2013, 01:25 PM   #361
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Okay... Getting there. Vbc(Q2) is lower than the total voltage drop which must mean there is another broken joint? What is the voltage across R1? Vbe of 1.15V for Q1 means it is probably dead... But I don't know why that would happen. Q1's pinout is CBE looking at the flat side.

The layout appears to be correct based on my guesses of where the pins are.
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Old 11th February 2013, 01:46 AM   #362
naf is offline naf  Indonesia
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hi kean,
do you mean Vce(Q2)?, i try to simulate with ltspice and Vbc(Q2) is less than Vdrop
Vce(Q2) = Vdrop

something wrong with my part,
here my real measurement
Q2
Vbe -0.62mv
Vce -2.4 v
Vbc 1.43 v

Q1
Vbe 1.15v (???)
Vce 1.46v
Vbc -0.7v
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Old 11th February 2013, 02:06 AM   #363
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Yes, I meant Vce.

Okay... Vbe-Vbc=Vce. For some reason this doesn't hold up in your measurements. In any case a Vbe of 1.15V means Q1 is fried; replace it, or test it for Hfe in case it really isn't bad, of which there is a remote chance.

If that doesn't work, add a lytic of any size to the input. Your goal is to get output AC below 1mV. With 136mV input it should be at least .27mV. Until then the circuit is still broken. If this doesn't work, then I'm flabbergasted.

Last edited by keantoken; 11th February 2013 at 02:15 AM.
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Old 11th February 2013, 02:14 AM   #364
naf is offline naf  Indonesia
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okay i'll replace the part and do meaurement.
but today i'm busy with my work.
will report back to you.

thank you.
naf
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Old 11th February 2013, 02:16 AM   #365
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Tinitus, anything interesting about the sound? Or does it just do what you expected?
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Old 11th February 2013, 03:46 PM   #366
naf is offline naf  Indonesia
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hi kean,
yes Q1 was dead, replacing a new one
here my measurement
dc in 23.36v
dc out 21.9v
ac in 0.172v
ac out 0.138v

q1
vbe 0.555
vce 1.08
vbc -0.22

q2
vbe -0.630
vce -1.79
vbc 1.09

i think this is correct dc value for q1and q2.
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Old 11th February 2013, 05:16 PM   #367
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That all looks right, except your input-output DC gives 1.4V whereas Vce(Q2) is -1.8V... And output AC is still way too high. And how did Q1 get fried!?

I'm sorry this is taking so long. How long do you wait after turning it on to measure it?

Measure again with 1k resistors in series with each probe, and the probe wires twisted. If this doesn't make the measurements consistent, then I think your meter must be flaky.
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Old 11th February 2013, 06:13 PM   #368
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by keantoken View Post
Tinitus, anything interesting about the sound? Or does it just do what you expected?
on my bass ? .... best I have had yet, or actually, much better, and almost where I want it
all commercial units are now out of my system

I can explain it very simple
there is none of all the strange ressonances or artefacts that plagued me a lot before
and now I can always find a setting that sounds right
also very nice that I don't need the compressor either
may be the compressor works better now, I don't know
but I don't need it, thats certain

actually, I still need that buffer, and with +/- symmetric power supply
so the next will also have your negative k-multiplier
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Old 11th February 2013, 07:04 PM   #369
iko is offline iko  Canada
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Hi keantoken, I can't find a model for the 2SA1930. Can you share it please?
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Old 11th February 2013, 07:18 PM   #370
iko is offline iko  Canada
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Actually, found this in another thread. Is this the one you're using?

.MODEL Q2SA1930 PNP(
+ IS=10.000E-15
+ BF=210
+ VAF=78
+ IKF=10.000E-3
+ XTB=1.5
+ BR=.1001
+ VAR=100
+ IKR=10.000E-3
+ ISC=10.000E-15
+ CJE=3.252E-12
+ CJC=63.196E-12
+ MJC=.33333
+ TF=83.239E-12
+ XTF=10
+ VTF=10
+ ITF=1)
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