Envelope problem D35 only 0.8mV instead of 12V

[Hesed]

VCO and VCF are looking good at the oscillosope and both waveform are sounding nice out of the resonance pot.

when i trigger the R146 with 5 volt i get 0.8mV on the multimeter.
R36 give a short click on the oscilloscope.

According to http://img836.imageshack.us/img836/8567 ... oguevo.png

C54 : OK

Q38 : OK
Q36: OK
Q37 : on right pin 0V instead of 3.3mV (could be this?)
Q35 : on right pin 0V instead of 0.6mV (or this?)

IC12 pin 6 is 11.89 instead of 37mV and it drop down when i trig R146.
I did several test and seems like no short to ground around envelope.

Nothing is getting hot.... any idea?

[Brassteacher]

VCO and VCF are looking good at the oscillosope and both waveform are sounding nice out of the resonance pot.

when i trigger the R146 with 5 volt i get 0.8mV on the multimeter.
R36 give a short click on the oscilloscope.

According to http://img836.imageshack.us/img836/8567 ... oguevo.png

C54 : OK

Q38 : OK
Q36: OK
Q37 : on right pin 0V instead of 3.3mV (could be this?)
Q35 : on right pin 0V instead of 0.6mV (or this?)

IC12 pin 6 is 11.89 instead of 37mV and it drop down when i trig R146.
I did several test and seems like no short to ground around envelope.

Nothing is getting hot.... any idea?

The trace leading from pin 6 of IC12 exits between pins 11 and 12 of IC12. If there is yet another bridged trace in that area, say between Pins 5 and 6 of IC12, or between pins 13, 12 and the trace leading from pin 6, you could easily get 11.89 at pin 6. Also, check to make sure nothing is shorting across R33, it could happen there as well.

After that is sorted out, check to make sure Q30 is ok, and IC12 itself also...

Good luck!

[Hesed]

Q30 was not in...not listed on mainboard part list... Mode Machine german build manual is also terrible missing and swapped part... if i had less experience i would stack at the IO still.

Now IC12 is getting all right voltage but still no 12V at D53 and the tone out of the resonance pot is much higher then before (without Q30).
In the time trying to figure out this problem i allready build the VCA and from right pin on VR8 i listen only a short click and no triggered note.

[guest]

q30 shouldnt have changed anything

make sure you are applying 5v
to the correct side of r146
it should be the side away from q37

then measure the voltages on q37 and q36
q37 should be around
0.0v
0.2v
0.6v
and q36 should be around
12v
11.8v
11.4v

[Hesed]

I measure with and without...

Q36 : 2.6 - 0.8 - 1.7 with 5V
11.91 - 0 - 11.91 no 5V

Q37 : 0.05 - 0.09 - 0.6 with 5V
0 - 11.90 - 0.01 no 5V

[guest]

measure the resistance
of r142 r143 r144 r145 and r146

power and ground are getting shorted together
when you apply the 5v

[Hesed]

I check the resistor before and after applying 5V.

142 : 9.91K - 0
143 : 9.93K - OL
144 : 9.85K - 0
145 : 9.92K - OL
146 : 21.65 - 0

OL on my multimeter is Overload or measuring range exceeded.

but still i cant figured out...

[guest]

desolder one leg of r143
and first check q37
to see which transistor is causing the problem

are you using 5v or 5.333v for the trigger voltage

turn power off
and measure the resistance to ground
on both sides of r146

[Hesed]

how should i check the transistor... for make a NPN test i have to dissolder also Q 37... right?

the voltage i'm using is 4.98 out or R3.

Only R144 and 145 are going to ground. Like in the schematics.

btw. thanks for your time

[guest]

ok thats the problem
r3 is not a good source of 5v

take the voltage from r78

[Hesed]

now at D35 nothing not even 0.8mV but instead on the POT8 right pin after some click give me a triggered note ... but only once.... i will continue till i found..

[guest]

connect it up
and measure the voltage
on either side of r146
just to make sure that the 5v is good there

if you want to be very sure of your 5v
you can take it right off ic20

[Hesed]

if i put my fingers beetween Q40 and Q41 (body contact style )i can ear the envelope rising and sound come thru POT8 of the VCA, also if i short pin 1&2 of q40 only or q41 only it come sound out.

do you think are the Q40 and Q41 broken?

Voltage drops to 1.7 and 0.1 on R146 when 5 Volt attached.

when i use 5V out of IC20 35 is again at 0.8mV.

[guest]

connect ic20 up to r146
and give me the voltages
on either side of r146
and on all 3 pins of q37 and q36

[Hesed]

done!

R146: 5.07V | 0.637V

Q37: 000.2mV | -009.7mV | 0.636V
Q36: 2.431V | 0.820V | 1,7V