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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Mackie Profx12 mixer
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? |
#2
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Mackie Profx12 mixer
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. |
#3
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Mackie Profx12 mixer
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" |
#4
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Mackie Profx12 mixer
"N_Cook" wrote in message ... 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. |
#5
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Mackie Profx12 mixer
On 18/04/2015 20:16, Gareth Magennis wrote:
"N_Cook" wrote in message ... 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. 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. |
#6
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Mackie Profx12 mixer
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 |
#7
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Mackie Profx12 mixer
just for future reference, can anyone identify the SMPS contoller
8 pin SOIC marking in 3 lines LT A46 082269CP C P |
#8
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Mackie Profx12 mixer
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 probably B not 8, Chinese 0B2269CP datasheet maybe off here http://badcaps.net/forum/showthread.php?p=205913 |
#9
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Mackie Profx12 mixer
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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