Collosalus 24 Build

[Spenzerleehorton]

Hi Guys,

Looks like im gonna need a little bit of help on this build.
I previously built the 2015 version of Collosalus and was never entirly happy with it, and ive now discovered i had put in all 20k trim pots, so the clock 500k trim was a 20k, still worked but that must be the reason i couldnt dial it in!!

onto this next build, i am waiting on a LM1458 for IC5 but have used a 5532 until it arrives so this also might be why there is a problem, but i thought they were both pretty much the same?

so first problem is that Regen pot doesnt do anything?
the flanging effect doesnt sound at all like before with the 2015 build?
the speed of the LFO is much faster than the previous 2015 build? so needs to be slowed down.

voltages all seem to check out apart from IC5 and IC6, on the pins where it says it varies on mine it doesnt?
my B+ is 15.00v and all other voltages are within 0.5v or closer.

all help would be very much appreciated.

[Spenzerleehorton]

First mistake was the 500k pot was wired wrong!
Will wait for new 4558 and LM 1458 to arrive, then I'll do another voltage sweep.

[Spenzerleehorton]

So far these seem like what I need to look at

2n5087 check this is in Q5
Check 500k trimmer as clock
Electrolytic correct values
C23 try bigger value than 62pf = 100pf or lower 47pf
C2 to 51pf
Try link pin 3 to 1 on 5532 to bypass first op amp. Remove r4 and link c3
C1 to 100nf

R19 from 1.4k to 2.4k as per 2015
C11 from 1uf to 100nf

[Spenzerleehorton]

C23 I've changed to 44pf and now the effect is starting to sound pretty good.
Measured the clock and getting somewhere between 15khz to 800khz
I still need to change a couple of electrolytic values which might change things a little as I didn't have correct values but put in bigger values.

[Spenzerleehorton]

Main issue now is regen pot still doesn't really seem to do anything?

[jimilee]

Pics would be huge. Otherwise, we'll just be guessing all day.


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[Spenzerleehorton]

ok here is a pic, not that it shows much as ive been over and over pcb with a magnifing glass!!
rebuilding the 2015 version as well now as it did actually sound ok even though it had the wrong trimmer in it!!
the made up resistors i measured before i put them in and they were the correct resistance, most were the 30k ones, which i used 2 x 15k.
the only different values ive used is c30 and c27 are 470uf, i cant see c27 being a problem but maybe c30 is an issue?
c2 is 47pf, c23 is 30pf and ive used 15uf tantalums in c20 and c21. IC5 is a 5532.
3 of the caps i made up with two caps to get to the correct capacitance, these are C1 = 33nf and c4 = 33nf and c5 = 3.3nf.

[Spenzerleehorton]

here is the voltages for the only tow ICs which seem to be off?

[Spenzerleehorton]

First test, I'll take all IC out and test b+ voltage to verify that this is all correct.
Then I'll put IC in and test all voltages again.
If off then go through and test all resistors.

[jimilee]

The pinout in the 5532 is the same, but they're not the same thing. That's your LFO section which would make sense why the regen pot is t doing anything. Have you gotten the replacement chip yet?


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[Spenzerleehorton]

Yes replacement chip has arrived and testing today, will report back.

tested voltages this morning and all voltages ok apart from IC6 pins 1-3?
Regen pot still doesnt work?
i have gone through and tested all resistors and put values they test at in circuit on the other attachment.

[Spenzerleehorton]

IC6 seems to be the only voltages that dont seem good on pins 1-3?

[Spenzerleehorton]

tested voltages this morning and all voltages ok apart from IC6 pins 1-3?
Regen pot still doesnt work?

attached is all voltages and values of resistors tested in circuit.
all cap values and are correct apart from the one shown.

[jimilee]

What's going on at R9? It's hard to tell if those two are soldered or one of them is broken.  Also, have you gone through the calibration process yet?

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[Spenzerleehorton]

Yes I have gone through the setup process several times, R9 is 2 x 15k soldered together.
IC6 pins 1-3 voltages?