buildafriend

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #20 on: February 23, 2018, 12:00:20 AM »
You should try pulling the channel cards. Divide and conquer is the name of the game


Brian Roth

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #21 on: February 23, 2018, 12:57:05 AM »
Looking again at the Elan I/O module schemos, I can now see how a rogue channel could inject noise into a channel of the stereo bus.  To try and isolate:

1.  Go through each I/O strip and push the "Monitor On" switches to off position while listening to the noise.

2.  If No Joy (and with the "Monitor" switches still off) then walk through the modules and press the "Rev" switches.

Bri

Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

pucho812

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #22 on: February 23, 2018, 11:53:21 AM »
Looking again at the Elan I/O module schemos, I can now see how a rogue channel could inject noise into a channel of the stereo bus.  To try and isolate:

1.  Go through each I/O strip and push the "Monitor On" switches to off position while listening to the noise.

2.  If No Joy (and with the "Monitor" switches still off) then walk through the modules and press the "Rev" switches.

Bri

Yes went there the first time I was out looking at the desk. No joy.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

JohnRoberts

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #23 on: February 23, 2018, 12:02:42 PM »
If the noise is intermittent, try wiggling wires/cables while listening. Tapping around with a pencil eraser can sometimes identify a flaky solder joint.

Semiconductors can fail gradually but generally go from bad to worse, not good/bad/good again.

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...

Brian Roth

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #24 on: February 23, 2018, 12:10:34 PM »
Yes went there the first time I was out looking at the desk. No joy.

And you also muted the Echo Returns on the master module?   Hmmmm...

bri

Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

pucho812

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #25 on: February 23, 2018, 12:36:34 PM »
And you also muted the Echo Returns on the master module?   Hmmmm...

bri

yes...  I know it's a separate path but if I solo something, no noise.   
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

Brian Roth

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #26 on: February 23, 2018, 06:17:00 PM »
Approx.  1-1/2 years ago I installed a 48 input Elan.  Clues indicated it was built mid 1990's before Sytek bought the product line.  The schematics I've managed to scrounge are fairly close to the actual desk, although the master motherboard/"ribbon chaos"  is quite a bit different since the master section sits between I/O modules 24 and 25.

However, earlier comments in this thread seem to imply the noisy desk is MUCH newer, so perhaps the schemos I have don't apply.

So, I'm also stumped.  Have you looked at the noise with an oscope?

Bri

Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

pucho812

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #27 on: February 23, 2018, 11:28:41 PM »
Yes... I scoped out the noise.  With a sine wave present in a channel going to the stereo buss, I see a nice clean sine wave when I measure at the ribbon output of the master, however it does bounce around like d.c. Slightly.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

ruffrecords

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #28 on: February 24, 2018, 04:00:36 AM »
yes...  I know it's a separate path but if I solo something, no noise.
What kind of sol is this. Is it solo in place (destructive) where it mutes all the other channels or is there a separate solo bus which feeds separately into the monitor via a relay/FET switch?

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

pucho812

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #29 on: February 25, 2018, 12:18:23 PM »
What kind of sol is this. Is it solo in place (destructive) where it mutes all the other channels or is there a separate solo bus which feeds separately into the monitor via a relay/FET switch?

Cheers

Ian

Yes separate solo bus, so when you solo it is a different set of chips feeding the monitor path. Yes it is destructive, solo in place
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.


JohnRoberts

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #30 on: February 25, 2018, 12:30:24 PM »
yes...  I know it's a separate path but if I solo something, no noise.
solo each channel one at a time... until you find the unhappy one.   

If none problem is in L/R bus

JR

John Roberts
http://circularscience.com
Tune it, or don't play it...

pucho812

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #31 on: February 25, 2018, 10:43:34 PM »
solo each channel one at a time... until you find the unhappy one.   

If none problem is in L/R bus

JR

that's the conundrum, went through every channel and no noise. so yes I would agree it is L/R buss but that was swapped with a known good replacement and the noise persisted. which has me now thinking  a faulty ribbon off the mother board.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

pucho812

Re: Noisy circuit, can a PCB trace or solder joint cause it? stumpped...
« Reply #32 on: February 27, 2018, 01:51:03 PM »
so sytek thinks it's a grounding issue and it's caused at location.  I have never heard a grounding issue ha results in that kind of noise.   I also would think if it was grounding that it would be in both sides of the stereo bus.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

pucho812

Well haza haza.  After a much back and forth with the manufacturer, mainly me insisting the fault is the motherboard and the manufacturer insisting it was not,  they sent out a replacement motherboard.

Took several hours to remove the old motherboard.  Unsoldered every wire.  Then soldered the same wiring to a new board. Once I did that, everything was working as it should.  All the noise and everything went away.   Could it have been that I touched up a bad joint? No,  I had already went there on the old motherboard.  Since the motherboard is traces and a few passive components, I can only assume at this point that  a trace cracked with a hairline fracture causing problems. The ribbon cables were reused and ok.  No failed passive components,  no active components. But anyway is all working 100% now.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

JohnRoberts

Well haza haza.  After a much back and forth with the manufacturer, mainly me insisting the fault is the motherboard and the manufacturer insisting it was not,  they sent out a replacement motherboard.

Took several hours to remove the old motherboard.  Unsoldered every wire.  Then soldered the same wiring to a new board. Once I did that, everything was working as it should.  All the noise and everything went away.   Could it have been that I touched up a bad joint? No,  I had already went there on the old motherboard.  Since the motherboard is traces and a few passive components, I can only assume at this point that  a trace cracked with a hairline fracture causing problems. The ribbon cables were reused and ok.  No failed passive components,  no active components. But anyway is all working 100% now.
A partial short from a bus to ground like from a solder blob or splatter, could cause an elevated noise gain, but they are usually visible.

Academic at this point with it fixed, congrats.

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...

pucho812

Thank jr.... onto the next thing😎
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.