StudioMaster Desk

[Neil Hampson]

I've just inherited an old StudioMaster Diamond-Pro 16-4-3 mixing desk as the previous owner considered it scrap. I've done a general clean and everything except channel 1 works perfectly. I know it's hard to diagnose on a forum but I'm hoping someone might be able to point me in the right direction.

With a line input the channel responds perfectly through the 'listen' bus or through either of the Pre-fade Aux channels. when routed though the fader the sound is there but faint, and there is a huge amount of noise/crackle on the channel peaking it out even on low gains. I've swapped the fader out and the fault does not lie with the fader, and the noise is constantly there even when the fader is not moved, the noise level does increase with the fader. Because it works OK on PFL and Pre-fade Aux, and the fault is there on Post-fade Aux and to the group/Main bus I'm suspecting it is something to do with the fader circuit but I don't have a diagram or any real knowledge to fault find more than this. I have had a brief look for any dry joints and re-soldered a couple of suspects but it didn't make any difference.

Can anyone offer any words of advice.

Otherwise, because the channel strips are modular, I'll just swap the PCB over with Channel 16 which is unlikely ever to be used.

 

Thanks in advance,

Neil

[vlfaudio]

Have you cleaned the insert points ? Dirt can get trapped in the normalling contacts, sometimes repeatedly re - inserting a jack will shift it, but better to use IPA based cleaner. , Note that switch cleaner will leave a load of oily residue inside your mixer. Canford used to sell a tool for the job, known as a Patchbay Burnisher.

[p.k.roberts]

Just had a quick look at the online manual and it doesn't look like the desk has individual channel inserts, so I'd start by wiggling L/R or Grp routing buttons, then check however the individual channel boards are connected together (back plane or ribbons?) and then move on to see if there are any socketed op-amps and half pull out and re-seat them. After that, you're probably looking at a dry joint or dead/dried out caps. Rather than trying to look for individual dry joints, it's sometimes easier to sit down with a mug of tea and Radio 4 and just re-flow the whole board.....

[Alec]

I'd start by wiggling L/R or Grp routing buttons, then check however the individual channel boards are connected together (back plane or ribbons?)

Definitely try this. I remember a 20 year old Behringer desk that had served its time, but had a number of channel faults. They were all down to dirty switches, and depending on the switch, a different symptom presented.

 

For example, a dirty HPF would kill the whole channel, as it's at the start of the signal chain. A dirty output selector, like Main LR, would pass signal to the pre-fade sends, but not to LR, and so on.

 

I suspect, as PK says, that it may be more internal than that.

 

You do realise, though, that this mixer is nothing special - and that it's original owner had appraised it fairly appropriately...?

[sunray]

I'd start by wiggling L/R or Grp routing buttons, then check however the individual channel boards are connected together (back plane or ribbons?)

Definitely try this. I remember a 20 year old Behringer desk that had served its time, but had a number of channel faults. They were all down to dirty switches, and depending on the switch, a different symptom presented.

 

For example, a dirty HPF would kill the whole channel, as it's at the start of the signal chain. A dirty output selector, like Main LR, would pass signal to the pre-fade sends, but not to LR, and so on.

 

I suspect, as PK says, that it may be more internal than that.

 

You do realise, though, that this mixer is nothing special - and that it's original owner had appraised it fairly appropriately...?

I think this is a little harsh. These days it is a bit lacking compared to the all knobs and whistles but that doesn't change the fact they were a very reasonable desk in their heyday and there are still loads of them in regular use.

 

20 months ago we put up a sound stage at a local event for about 20 local bands through the day, one of the bands front ended our system with their SM desk to do their own mix.

 

I know of a church with one and another church with an 8-2. All perfectly serviceable and performing in the way needed.

 

Personally I've never found a need to move on from Soundcraft F1's and SX's or Alice series A. However I'm nowhere near the league of many operators on here.