SOLVED (R106 wrong, IC8 bad)

[mome rath]

ok

1. can't get more than 6V DC across C5
2. can't get more than 13V DC across C3
3. IC20 getting hot hot hot
4. not getting 5.3 or 12 V for the first two tests in the VCO
5. not getting 5.33 or 12V @ J4 on the main board

briefly got some noise from the waveform switch with headphones
when i disconnect/connect the molex jumper underneath the uController, I sometimes get a single burst of one note


I'm done with these things after this one

[guest]

is this an old one or a new build

disconnect j4 and j3
and see what the powersupply voltages do
you definitely have a short on the 5v line

[mome rath]

is this an old one or a new build

disconnect j4 and j3
and see what the powersupply voltages do
you definitely have a short on the 5v line

new build

testing PSU voltages again... edit: hold on

just had a good square sound come out after accidentally putting my hand on the waveform switch. then i couldn't replicate it... and IC8 is hot as HELL

[mome rath]

ok with j3/j4 removed, I get 12.8 and 13.3 V DC on C3 and C5, respectively


also, the sound off the waveform switch was tunable with the tune pot

[guest]

what are the voltages on j4 and ic20
with the jumpers removed

[guest]

and check that ic8 is orientated properly

[mome rath]

the pin designations are looking at the solder side of the power board, left to right

IC20:
pin1: 4.98V
pin2: 0V
pin3: 13V

J4:
pin1: 12V
pin2: 0V
pin3: 5.18V

[mome rath]

and check that ic8 is orientated properly

yeah, all ICs are in the proper orientation

IC8 only gets hot if pins 1-6 of j3 are connected

[mome rath]

with pins 1-6 of j3 disconnected I get the proper 5.3ish and 12v in the VCO test

[guest]

what value resistors are you using
for the leds connected to ic8
measure them with a meter

there are either shorts around ic8
or the chip is bad
check the part number on it as well

[mome rath]

what value resistors are you using
for the leds connected to ic8
measure them with a meter

there are either shorts around ic8
or the chip is bad
check the part number on it as well

r263 is a 10k but measures 7.5k

ic8 is a 595 as it should be; I'll try to swap it out


I don't have any LEDs installed yet--those are the only things left out

[guest]

after you remove ic8
plug j3 back in
and see what the voltages on ic20 are

[mome rath]

after you remove ic8
plug j3 back in
and see what the voltages on ic20 are

1: 4.95V
2: 0V
3: 12.28V

[guest]

is it all back to working sans ic8
does sound come out

[mome rath]

nothing's working :<