Mackie Profx12 mixer

N

N_Cook

Guest
All channels are out, no mute LED on pushing any mute button, FX display
responds to changing the coding knob and just phono input to output
works but none of the 12 channels.
I don't suppose anyone has the sequence of voltages for the main ribbon
off the SM power supply?
 
I suspect its ridiculous "design" again. One of these annoyed me before.
There is an overall BREAK switch that mutes all channels but not phono
connectors CD in. But and a very big BUT , there is no LED associated
with that button in the main section. Accidently press it and there is
no evidence of it being pressed and you have a permanently "dead" system.
Along with you naturally assume , on each channel, the LED would light
on pressing the adjascent mute switch and otherwise light on overload,
as legend says OL. But no , once again simple 1 pole latching switches
and no LED reminder of any particular channel being muted. The LED is
just what the label says , OL , and not a MUTE reminder at all. I
thought Mackie was supposed to be a good name in htis sort of stuff.
A pierced plastic shroud will be fitted over that crass killer button,
so it cannot be activated accidently. If required then would need
inserting a pen tip or something.
 
This silent killer button is right on the edge, mid-way up the right
side , just where the ball of the right thumb would press , in normal
carrying.
In the troubleshooting section of the user manual, no mention of this
crass failure mode.
In the bit about the BREAK switch it does though say
"Check this switch first if you are having trouble with no sound in the
system"
 
"N_Cook" wrote in message news:mgu3tl$r1i$1@dont-email.me...

This silent killer button is right on the edge, mid-way up the right
side , just where the ball of the right thumb would press , in normal
carrying.
In the troubleshooting section of the user manual, no mention of this
crass failure mode.
In the bit about the BREAK switch it does though say
"Check this switch first if you are having trouble with no sound in the
system"



It would have made more sense for Mackie to have labelled that switch
"MUTE", rather than make up a new name that is not in common usage.

Maybe it was a bad Chinese translation somewhere along the design route.



Gareth.
 
On 18/04/2015 20:16, Gareth Magennis wrote:
"N_Cook" wrote in message news:mgu3tl$r1i$1@dont-email.me...

This silent killer button is right on the edge, mid-way up the right
side , just where the ball of the right thumb would press , in normal
carrying.
In the troubleshooting section of the user manual, no mention of this
crass failure mode.
In the bit about the BREAK switch it does though say
"Check this switch first if you are having trouble with no sound in the
system"



It would have made more sense for Mackie to have labelled that switch
"MUTE", rather than make up a new name that is not in common usage.

Maybe it was a bad Chinese translation somewhere along the design route.



Gareth.
Click to expand...

I would have thought in these SM days, if they had to use 1 pole
latching switches in such critical areas , it would be possible to
buffer the switch action to control audio and an LED,add an LED to the
Break sw and double function for each of the Overload buttons , just
OR'd together to the OL LED, so flickering OL for overload and
permanently on for MUTE. I imagine combined continuous overload and mute
in some very rare circumstance would be ambiguous

for the record
SMPS is fine testing in isolation with no load.
output ribbon is
n/c,n/c,7.8V,0,48V,+15,+15,0,0,0,-15,-15
pin 4, is labeled digital gnd so presumably 7.8V is the supply for 5V
and 3.3V regulators on the other boards somewhere, p8,9,10 labeled
analogue gnd, make contact to the common of the TO220 rectifiers, ignore
the frame ground .
Butchering a black Bulgin 1436, 3A main plug , seems just about right
size to locate as a shroud over and around the silent killer BREAK
button with an activation hole for a pen or key, neatly fixed to a
convenient chassis screw nearby.
 
A small metal standoff under the srcrew to stop the underneath
fibre-reinforced plastic "standoff" of the ex- L1436/P plug from deforming
http://www.diverse.4mg.com/mackie_fudge.jpg
still shows "mutes all channels" legend , but not the "Break" now
 
just for future reference, can anyone identify the SMPS contoller
8 pin SOIC
marking in 3 lines

LT A46
082269CP
C P
 
On 20/04/2015 19:08, N_Cook wrote:
just for future reference, can anyone identify the SMPS contoller
8 pin SOIC
marking in 3 lines

LT A46
082269CP
C P
Click to expand...

probably B not 8, Chinese
0B2269CP
datasheet maybe off here
http://badcaps.net/forum/showthread.php?p=205913
 
Another crass aspect of the "design". There is a mute LED for muted
effects switch, which anyone should be able to tell by listening whether
FX is muted or not.
 
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