I went back to test my PSU again. There's something wrong. The output of J4 is reading about 11.83DC (within tolerance according to fab manual) and 5.33vDC.
However...
The voltage across C3 and C5 should be 15vDC, but I get 12.2vDC on C3 and 13.5vDC on C5.
The voltage across C4 and C6 should be between 4.5 and 5.5vDC however I get 5.08vDC on C6 and 12.vDC on C4.
I also checked the gate (D35) with respect to J4 pin 2 and I get 0vDC when I have it in random mode.
no sound.. VCO DC approx correct, but not AC
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I tested the joint with my meter, but there was no solder bridge. I cleaned off some of the solder as well anyway. Still same results. This has me so unbelievably frustrated. I'm tempted to just order a second kit and toss this one. I'm pretty sure I have a bad part somewhere as I am extremely confident that I didn't put anything in wrong.
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do not get frustrated
youve actually found your problem
your gate is not actuating
therefore the vca does not turn on
check the microcontroller side of r146
this should go to 5v when the gate is on
the best way to test this is to put it in keyboard mode
and hold down a key whilst looking for voltage
youve actually found your problem
your gate is not actuating
therefore the vca does not turn on
check the microcontroller side of r146
this should go to 5v when the gate is on
the best way to test this is to put it in keyboard mode
and hold down a key whilst looking for voltage
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Usually I use my frustration to rid my projects of demons as though it were holy water or something... I guess x0x is a different beast all together. Perhaps I should work on it inside of a pentagram?
Anyway, I would completely agree with the gate signal being the problem if it weren't from my DMM picking up 0vDC and 0.07vAC on the right pin of the resonance pot, which tells me there's also something in the filter that is mucked up. I suspect that the extremely low outputs I'm getting on the VCO are just due to the loading of my soundcard when I tried to record. I get decent (vDC) values when I use my DMM.
I've been wanting to get a scope for home for a while now and I think now is the time to do it.
Anyway, I would completely agree with the gate signal being the problem if it weren't from my DMM picking up 0vDC and 0.07vAC on the right pin of the resonance pot, which tells me there's also something in the filter that is mucked up. I suspect that the extremely low outputs I'm getting on the VCO are just due to the loading of my soundcard when I tried to record. I get decent (vDC) values when I use my DMM.
I've been wanting to get a scope for home for a while now and I think now is the time to do it.
- subatomic
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djarago wrote:The VCO when I probe at the waveform switch gives me approximately 1.5VAC on pin 3 and 0.75VAC on pin 1. I get 6.4VDC and 9.4VDC on those same pins respectively.
I have values very similar to this,
can anyone explain why we might be getting the low AC instead of the 4-5VAC like the fab manual says?
Is this normal?
More info:...
Probing with the headphone (it's cheap earbuds) on the center post of the waveform switch I hear a saw and a dulled sqr wave (which I expected), with a loud pop when switching _to_ the sqr wave. Using the oscilloscope I see waves matching the fab manual pictures for both sqr/saw...
I have only build the VCO and PSU. Nothing else is built yet...
Last edited by subatomic on Mon Nov 07, 2005 1:58 pm, edited 4 times in total.
- subatomic
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Please be positive and constructive with your questions and comments.