SSL 4K fader goes maximum at 100% down???
- Thread starter jwhmca
- Start date
Help Support GroupDIY Audio Forum:
Andy Peters
Well-known member
jwhmca said:
Dunno what a "4k" is -- Yamaha PM4000? Midas Heritage H4000? Allen & Heath GL4000? Is the fader just VCA control or does audio pass through it?
radardoug
Well-known member
Could be dirty fader, could be the thumbwheel VCA group switch.
pvision
Well-known member
Some BBC consoles had PFL on a microswitch on the fader endstop. Is that what is happening? Or do the faders have an endstop switch fitted?
Worth checking
Nick Froome
Worth checking
Nick Froome
SSLtech
Well-known member
SSL fader voltages go from zero to five volts.
Guess which end is the plus five volts end? +10dB at the top, or minus infinity at the bottom?
Counterintuitively, it's minus infinity.
So, what's happening is as you draw the fader down towards you, the voltage is RISING. -Then at the very bottom, it's losing contact with the trace, the wiper voltage is disappearing, and it drops to zero volts, giving you maximum output.
I bet dollars to doughnuts that the faders are 3000 series, and that soemone has misaligned the conductive plate. It's sitting just a little too high "up" the fader path, so when you pull the wiper down, it 'over-runs' the conductive area.
Disassembly, a quick wipe down, CAREFUL alignment (lube the slides with trumpet valve oil or trombone slide oil while you're in there, after polishing them, for the ultimate tactile joy) and reassmbly, and your problems should be gone.
Do this in a clean area, don't do too many at once, and BE CAREFUL OF THE WIPER. Do not try to "force" the conductive insert "the wrong way" past the wiper 'brush', or there's a very good chance you'll bugger the wiper.
I have some faders here if you break any.
Keef
Guess which end is the plus five volts end? +10dB at the top, or minus infinity at the bottom?
Counterintuitively, it's minus infinity.
So, what's happening is as you draw the fader down towards you, the voltage is RISING. -Then at the very bottom, it's losing contact with the trace, the wiper voltage is disappearing, and it drops to zero volts, giving you maximum output.
I bet dollars to doughnuts that the faders are 3000 series, and that soemone has misaligned the conductive plate. It's sitting just a little too high "up" the fader path, so when you pull the wiper down, it 'over-runs' the conductive area.
Disassembly, a quick wipe down, CAREFUL alignment (lube the slides with trumpet valve oil or trombone slide oil while you're in there, after polishing them, for the ultimate tactile joy) and reassmbly, and your problems should be gone.
Do this in a clean area, don't do too many at once, and BE CAREFUL OF THE WIPER. Do not try to "force" the conductive insert "the wrong way" past the wiper 'brush', or there's a very good chance you'll bugger the wiper.
I have some faders here if you break any.
Keef
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