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Slide time = zero and headphone out dead
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Slide time = zero and headphone out dead

by t0mt0m on Fri Jul 08, 2016 4:20 am

Hi,

I have one of the beautiful aluminium x0xb0xes from midiot.net.

headphone amp doesn't work since I first checked, but I don't care about it.
It took years to even find it out, because I see no usage for headphones on my x0xb0x,
but I thought I'd mention it, because maybe there's some connection.

The real problem is:
I can play the x0x for hours and it will sounds great, but sometimes the slide time will go to 0 - meaning notes are joined, but with instant pitch changes.
Sometimes the Accent attack time would go to 0, too (no more "wow", but "ow"). Sounds interesting, but not like a 303 anymore.
Shaking the unit or knocking on the sideplate would sometimes bring it back to normal operation.

I've checked the unit for loose connections/parts a year ago, and all I could find was that one of the flat ribbon cables looked to be almost broken.
I've resoldered it, but that didn't help. (Unfortunately I can't remember which one it was)

I want to check the unit again this weekend and will post detailed results, if I can find something.

In the meantime - does anyone have an idea what could possibly be responsible for this behaviour, so I can narrow it down?

many thanks in advance.

t0mt0m
 
Posts: 13
Joined: Thu Nov 15, 2007 5:47 am
Location: Austria

Re: Slide time = zero and headphone out dead

by antto on Fri Jul 08, 2016 2:17 pm

for the headphones - check if you have the "6V" supply voltage going on, because that one is only used for the headphones amp and pretty much nothing else

for the accent "wow" it smells like the resonance pot is acting weird
it's dual, one half of it is used for the filter resonance, but the other half is completely separate, it deals with the accent "wow" and C13 (forming something like a peakfollower/lowpass)
it would help if you can record a short audio clip of this with the envmod set to zero, cutoff/resonance/accent set to max
but otherwise it's either that or maybe C13 is not quite soldered in

for the slide, measure the voltage at R59 (the leg towards the cpu) while playing a pattern with slides.. it should jump between 0 to 5V but it shouldn't stay flat 0.0V

antto
 
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Re: Slide time = zero and headphone out dead

by t0mt0m on Sat Jul 09, 2016 5:55 pm

thanks, antto!
I haven't found the time to check your suggestions but i will asap.
But I've recorded an audio clip of the x0xb0x.
unfortunately I couldn't provoke the accent attack thing, i could however capture the slide time failure.
the only thing i had to do was shaking/knocking on the unit.

http://picosong.com/xW3k/

I will try to do the tests tomorrow and post the results.

t0mt0m
 
Posts: 13
Joined: Thu Nov 15, 2007 5:47 am
Location: Austria

Re: Slide time = zero and headphone out dead

by antto on Sun Jul 10, 2016 5:32 am

if shaking it causes that, then i think some component is not quite soldered in
check C35, check IC12 - if it's in a socket, ensure that it makes good contact with the socket, and look around the components in that area for anything strange

antto
 
Posts: 1617
Joined: Thu Apr 15, 2010 3:21 pm
Location: 127.0.0.1

Re: Slide time = zero and headphone out dead

by t0mt0m on Sun Jul 10, 2016 2:07 pm

antto, you've nailed it with impressive precision!

The negative leg of C13 hasn't been soldered in. It must have been overlooked.
I wonder how it still had electrical contact and I couldn't provoke the accent error yesterday.

Also, C35 had one cold solder joint. I would've never found it since it looked perfectly fine. But I was able to pull the leg out of the joint and back in again, it was that loose.

Found a few other joints that looked suspicious and resoldered everything.
Yay, the x0xb0x sounds flawless again!!!

(headphone out is still dead, but whatever...)

Thank you, antto! you've saved me a lot of time! :)

t0mt0m
 
Posts: 13
Joined: Thu Nov 15, 2007 5:47 am
Location: Austria

Please be positive and constructive with your questions and comments.