yayajohn wrote:
Because I can clear the problem (albeit only temporary) by jarring the console do you think it might be something as simple as a loose part contacting one of the circuit boards?
Or a loose connection somewhere?
Well, the desaster is, it can be anything.
Cold soldering joint(s)
Ribbon cables
other parts failure,- also temporary only, possible temperature dependent too
So 1st, you´ll need schematics/service manual to sort out potential problems and isolate the issue.
I still own a Mackie VLZ 1604 where the left main bus temporary fails, sometimes completely or sometimes lower level only and introducing noises you described above too.
Since month, my techs and me we´re unable isolating the issue even we disassembled the whole thing 2 times and thought it works again,- then after days the issue came back.
According to ribbon cables:
Not everything is connected by ribbon cables even these are potential cause of failures.
In my Mackie, they only connect the channel-, subgroup- and main-inserts and these are connected to a patchbay which works, so contacts are closed w/ nothing inserted and the main left bus should work regardless of ribbon cables when L+R is routed in a channel.
Just only an example but Behringer copied Mackie in the 90s, isn´t it ?
It can also be a haircrack on the large main circuit board and the chance increases w/ the size of the mixer because 8 channels need less circuitboard estate than 32 channels p.ex..
Larger boards flex much easier.
yayajohn wrote:
Or perhaps simply clearing the dust or spraying some appropriate Deoxit type of spray?
I´m not a big fan of spray at all.
You might do the work cleaning pots and faders w/ compressed air and I made some good experiences w/ Teslanol T6 for rusty vintage (Allen Bradley) pots, but doubt that´s cool for cheapo mixer´s cheapo plastic pots.
It´s all temporary fixes only ...
Super 10 switch cleaner is good for switches and rotary encoders but agressive to plastic parts, so careful dosing rules.
Deoxid itself is top notch but small quantity for a high price,- and as I said, it´s only usable for the moving parts in a mixer or chip´s legs
when socketed.
Ribbon cable might be socketed too, but the sockets themselves are soldered to the circuit boards, might have high count of very thin contact legs and all the components were soldered in one go during manufacturing process.
Now, w/ your soldering iron, you might damage more parts by heat just because your soldering job is slower and normal soldering is much hotter than SMD soldering which is hot air.
yayajohn wrote:
Are most of these large boards easily accessible to get under the hood or is it a nightmare?
The larger these mixers are, the more disassembling and re-assembling becomes a nitemare,- just because almost everything is on only one circuit board which fills the bottom of the case.
The main nitemare of these mixers is, you cannot remove just only one channel for repair, you have to disassemble the whole thing instead.
It´s the most horrible and most time cosuming job for service techs,- removing all pot caps, fader caps and switch caps, unlock all screws holding pots and sort all that s##t for later assembly.
Then take care for all the ribbon cables and pull out that big mainboard without damage and flexing, just only to find out it´s too big for your workbench where are all the tools you need already and so on.
When all channel LEDs flicker, it might be the PSU too ...
Does your mixer work w/ an external PSU ?
Maybe it needs to be recapped !
yayajohn wrote:
Wishful thinking on my part but i'm hoping it might be something simple.
In most cases it´s simple, but finding it isn´t.
Once found, it´s matter of parts availability and/or service friendlyness of the device.
How many hrs of work you want to invest for a 20y old Behringer mixer showing age issues ?
What do you think you´d get for it @ebay even it worked perfect ?
Possibly nothing because noone wants it anymore today.
I have 2 8bus consoles in the closet, more worth a restauration than any Behringer, Mackie etc. just because they are half modular and no SMD technology.
You can pull panels and each panel is four channels while under the roof, each channel is devided into 3 or 4 circuit boards, so you can restore/repair just only the EQ, the aux section or gain section and so on.
The PSU is separate 19" rackmount.
I have spare parts, complete channels, ribbon cables, switches, pots and a service manual and noone wants ´em even these are low noise and sum well.
These cost DM 10.000,- a piece in the late 80s, but the company went out of biz ...
When buying similar today it´ll cost ~EUR 15.000,- +++
Since all mix in the box it´s hard to find people buying (used) mixers.
The experts and pro studios want Neve, SSL, Big by Langley, Harrison ...
Bud
my two cents