Extra pulse sound during play.

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guest
 
Posts: 3155
Joined: Fri Feb 17, 2006 5:35 am

Post by guest »

the bass boost caps come after the filter
so if the pulse sound is in the filter
its probably not causing the problem

can the pulse sound be heard in the vco

the pulse sound is in time with the gate going on and off
so it has to be related to that somehow
and if the problem is in the vcf
the only way those two things are related
is through the power supply and the env mod

you could try lifting one side of d37
and see if the problem is coming from the envelope section

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k-rite
 
Posts: 65
Joined: Mon May 09, 2005 11:43 pm

Post by k-rite »

i actually built a second x0x psu/io board and hooked it and the problem still exists, so i'm 99.9% sure it's not the psu. that means it must be the envelope.

i went a head a replaced q38 and now the raw waveform sound is real loud and the acid sound is really quiet (i can barely hear it). is there any way to test caps while they are mounted to see if they are good?

guest
 
Posts: 3155
Joined: Fri Feb 17, 2006 5:35 am

Post by guest »

by power supply problem
i mean noise communicated between sections
via the power supply

so there could be some section of the circuit
say the gate section
which is drawing more current than it should
this will pull down the voltage on the power supply
irregardless of which powersupply i s attached
as the problem doesnt exist in the powersupply board

with your tests replacing q38
where are you listening to the signal
and is the pulse still apparent
is there a volume difference at the headphone output
as compared to the previous q38

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k-rite
 
Posts: 65
Joined: Mon May 09, 2005 11:43 pm

Post by k-rite »

guest wrote:with your tests replacing q38
where are you listening to the signal
and is the pulse still apparent
is there a volume difference at the headphone output
as compared to the previous q38
i'm listening on the mix out and headphone out, there is no difference is the volume level, but its all raw pulse sound and no acid now. none of the pots do anything, except the volume. i checked the solder joints of q38 and they look good so, why are things getting worse? ahhhh! now where do you suppose i check?

guest
 
Posts: 3155
Joined: Fri Feb 17, 2006 5:35 am

Post by guest »

its odd that replacing q38 would make such a difference
perhaps there is something wrong with that section

can you jumper from the 12v rail to
the d36 r134 juncture
this will turn on the vca continuously
and will verify that the vca is getting signal
and is working properly

also there are two gate signals that get sent to the vca
one is the actual gate signal
and the other is the gate pulse which is generated by q38
and is used to create the attack and decay for the vca
either one of these might have problems
so bypassing one or the other might make
the problem go away

can you still here the signal in the vcf

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k-rite
 
Posts: 65
Joined: Mon May 09, 2005 11:43 pm

Post by k-rite »

looks like my psu is putting out too much power now. i got like 20V coming out of j4 where there should be 12v and 12v coming out of where there should be 5.33v. i went over all of the tests in the psu make build section and everything checks out. i think i hooked up j4 to the main board wrong once and something happened. this is just not working out for me. anyway i need to fix that now too. any ideas?

guest
 
Posts: 3155
Joined: Fri Feb 17, 2006 5:35 am

Post by guest »

sounds like your lm336z has blown out
what is the voltage at pin5 of ic23
check the solder joints on the lm336z

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