Dear all,
I have a few concerns that you may be able to help me with:
1) There is a HORRIBLE hum by default when I power up and jack in. If I tilt C4, however, this goes away. Bear in mind I'm not grounding on C4, I'm only touching the plastic case and, depending on how I bend it, the hum is there or not. I intend to rework the joint, but was wondering at the explanation for the current phenomena.
2) The 'random' setting works, so the osc-vca-vcf-envelope are working, as does 'keyboard' mode. When I go into step sequencing, however, LED #9 doesn't light up. Instead, #8 lights in place of #9, then we jump to #10. It seems that the sequencer section is ill in general.
My USB isn't recognized so I'm sure that I botched that job. Would that possibly explain any of the weirdness I'm seeing?
Any ideas out there?
Thanks,
-C
86 lives! (in a persistent vegetative state)
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- controlvoltage
- Posts: 242
- Joined: Tue Aug 09, 2005 12:17 am
for what you are describing, I would suggest, get some good solder (with lead and a rosin core) if you don't have some already... and go over all your welds/joints in the sequencer section very carefully... sounds almost like there are some pins bridged together or a short somewhere causing the curent behaviour. So, use soder-wick or some other desoldering braid and remove excess solder anwhere it is built up excessively. This can re-flow and leave very good joints in one step if you do it right.
if you re-do C4 the hum may go away, not sure about the cause but bad connection to ground can cause all sorts of hum and sonic nastiness.
Oh and get a bit of paste flux for the USB section, and a finely pointed soldering tip if possible. The flux will make it so much easier. If however you have already got the USB chip on there in the correct orientation (check pin 1 on the PCB vs. the markings on the chip vs. the photos in the fab guide) -- you may be able to get it working using only some desoldering wick to clean up the solder on the legs. work under good light! It really helps.
if you re-do C4 the hum may go away, not sure about the cause but bad connection to ground can cause all sorts of hum and sonic nastiness.
Oh and get a bit of paste flux for the USB section, and a finely pointed soldering tip if possible. The flux will make it so much easier. If however you have already got the USB chip on there in the correct orientation (check pin 1 on the PCB vs. the markings on the chip vs. the photos in the fab guide) -- you may be able to get it working using only some desoldering wick to clean up the solder on the legs. work under good light! It really helps.
- ceedub
- Posts: 69
- Joined: Mon Sep 26, 2005 11:59 am
thanks for the tips!
The darn thing isn't even making noise anymore, so its condition has degraded.
I reworked the C4 joints, and will go over the sequencer section like you suggested. I am using silver/lead .022 with rosin core, a Weller station with a small tip and so I'm ashamed if I botched it
One other thing to note: I improvised with some LEDs at the 1,5,9,13 spots, and they are super dim. Do you think that lack of voltage may also contribute to the overall symptoms? In otherwords, would an incorrect "resistor" in those LED slots gum up the electronics?
Thanks,
-C
I reworked the C4 joints, and will go over the sequencer section like you suggested. I am using silver/lead .022 with rosin core, a Weller station with a small tip and so I'm ashamed if I botched it
One other thing to note: I improvised with some LEDs at the 1,5,9,13 spots, and they are super dim. Do you think that lack of voltage may also contribute to the overall symptoms? In otherwords, would an incorrect "resistor" in those LED slots gum up the electronics?
Thanks,
-C
- controlvoltage
- Posts: 242
- Joined: Tue Aug 09, 2005 12:17 am
if the only change is in the LED or the resistor in-line with it, it would not change the logic in any way... a different resistor should just change the amount of current lighting the LED.
perhaps make sure all those interconnecting wires are in good shape & well-soldered? Could be your signal getting lost in transit somewhere.
it never hurts to doublecheck the orientation of all components... that solved the final problem with mine after i'd finished it... had one backwards transistor on the VCA. You could be so lucky...
perhaps make sure all those interconnecting wires are in good shape & well-soldered? Could be your signal getting lost in transit somewhere.
it never hurts to doublecheck the orientation of all components... that solved the final problem with mine after i'd finished it... had one backwards transistor on the VCA. You could be so lucky...
- controlvoltage
- Posts: 242
- Joined: Tue Aug 09, 2005 12:17 am
I had some irregularity in the sequencer section of my x0x, and it was cured by some combination of reworking solder joints, removing excess solder and removing accumulations of flux. I also checked the I/O board very carefully and some amount of similar rework also fixed a problem I'd had with MIDI sync.
- ceedub
- Posts: 69
- Joined: Mon Sep 26, 2005 11:59 am
Thanks, CV!
I have a good feeling going into this evening, now, knowing that you had similar issues and they were so simply taken care of.
I tried removing the flux spatters with a dry toothbrush to no avail. Do you have any solvents in mind for cleaning that crud away?
Thanks again for your tips (I was about to cry yesterday after it started going berzerk).
-C
I tried removing the flux spatters with a dry toothbrush to no avail. Do you have any solvents in mind for cleaning that crud away?
Thanks again for your tips (I was about to cry yesterday after it started going berzerk).
-C
- controlvoltage
- Posts: 242
- Joined: Tue Aug 09, 2005 12:17 am
- brandon daniel
- Posts: 160
- Joined: Sat Mar 12, 2005 12:46 am
Careful with that. Isopropyl is right, rubbing alcohol not so much. Rubbing alcohol is usually only 70-something percent isopropyl, and has lanolin which will make your board sticky. get 90-something percent isopropyl w/o lanolin, you'll be way better off.controlvoltage wrote:in a pinch, isopropyl (rubbing) alcohol seems to take up flux fairly well... with no ill-effects that I've ever observed. If it was good enough for Dr. Moog it's good enough for me.
Commercial flux cleaner as specified may do a neater job though; I don't know.
Please be positive and constructive with your questions and comments.