|
|
Post by tonycamphd on Sept 14, 2013 16:47:53 GMT -6
is this noise??? these samples are 2 identical soundcraft delta 200 input strips, JW mods, one is making a strange crackling sound, the volumes on the samples are extreme, and never to be seen in the real world, they are cranked all the way up to expose the problem. The first part of the clip is a properly functioning strip, all my other strips sound like this one. The second part of the clip is the weird one. It passes audio, but something is not right..so...any ideas? edit; i have reflowed the solder joints, switched opamps and transistors from the bad module with a good one, no change thanx T soundcloud.com/tonycamp/help-me |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Sept 15, 2013 0:17:58 GMT -6
Hmmm, stupid question...did you clean the insert jacks?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Sept 15, 2013 0:19:57 GMT -6
Otherwise i would check for a bad electrolyte capacitor...
|
|
|
|
Post by tonycamphd on Sept 15, 2013 0:49:53 GMT -6
thanx small, that sound is coming from the monitor out of the master channel, all the channel strips sound fine routed through the master, except this one, i replaced all the caps with brand new elna silmics on this channel, what are the chances of getting a brand new bad cap? I checked the polarity(all's good), and I will test them for capacitance like you suggest, is there another test to check for a faulty cap?
thanx again
T
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Sept 15, 2013 1:55:58 GMT -6
And...sorry, but just got another idea...ribbon connector contact probs? (... just the typical things i checked first at the used consoles i serviced...)
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Sept 15, 2013 2:06:12 GMT -6
Ah, Tony, you are right, it is unlikely one of the electrolytes (assuming you checked the elmas each before soldering...). Well, normally i try to spot a bad cap optically first (convexe top and other signs of failure...) but with brand new caps - this is useless. They cannot show signs of electrolyse, this only happens after longer time of actual usage. So it is the hard way, desoldering a leg (or both) and measure...  But well, if you checked everything possible contact-related, all opamps (sockets), transistors etc...? Something *has* to be gone bad, so going from the most obvious to the least obvious.... |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Sept 15, 2013 2:11:58 GMT -6
Is this specific noise also coming out of the insert??
This can show you, in which part of the circuit the noise is located, (before or after the insert-point), this way you can trace the audio path, and locate the prob better - step by step, and must not check every part....
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Sept 15, 2013 2:23:08 GMT -6
And as for the ribbon, if you change the position of the strip, is the noise still there? I mean - plug it in another position of the ribbon...and check...maybe it is not the strip itself...
|
|
|
|
Post by tonycamphd on Sept 15, 2013 10:29:26 GMT -6
And as for the ribbon, if you change the position of the strip, is the noise still there? I mean - plug it in another position of the ribbon...and check...maybe it is not the strip itself... thanx small, i have repositioned the strip at different points on the ribbon connecter, same result, i get the noise on the D/output also, i have not checked the insert point on its own, i'll do that later today. I think i'm going to pull each cap and test, the poor pcb is taking a pounding!! i've lifted a few traces already, even though i'm using the hakko 808!  thanx T |
|
|
|
Post by svart on Sept 16, 2013 9:50:22 GMT -6
Sounds like a bad cap. I know you replaced them, but it's possible. It's also possible that they just don't work in your setup, having too much leakage current flowing through them or something. It's almost impossible to tell without full testing.
Such is the life of DIY, you never really know what the outcome will be when just changing parts.
It's also possible that it's a ground issues. I've heard the "frying bacon" from a few channel strips that had poor grounding. Try clipping a heavy ground strap to the PCB ground and then to the chassis and see if it changes.
And the last thing would be a bad insert point or something. Ram a clean plug into your insert jack a few times to clean it a bit and see if it goes away.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Sept 16, 2013 13:44:22 GMT -6
smallbutfine is a dude, respect!
|
|
|
|
Post by jimwilliams on Sept 23, 2013 17:46:07 GMT -6
Jack an oscillator into the front end and trace down the circuit with a scope probe. Where the signal stops or goes off is where the problem lies...
|
|
|
|
Post by tonycamphd on Sept 24, 2013 15:49:19 GMT -6
Jack an oscillator into the front end and trace down the circuit with a scope probe. Where the signal stops or goes off is where the problem lies... Ok jim, i probably should have left well enough alone, but i'm getting into the, i really want to understand how this works, and trying stuff stage! Btw, the difference between the stock and your modded channel strip is absolutely laughable, like peewee herman vs Hulk hogan! noise floor and bottom solidity are stunning! twisting the hi shelve to the max is really quiet at pinned volume on the channel and master simultaneously! really awesome mod you came up with here, the board qualifies as amazing! I'll see you in a bit with my adcom pro, and a couple more strips for super modding, thanx jim T |
|
