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Studiomaster Mixdown Classic 8 Console Problem

apauly

Mar 8, 2023
2
Joined
Mar 8, 2023
Messages
2
Hi! I've been working on a Studiomaster Mixdown Classic 8. I opened it up to make sure the levels were selected properly (i.e. balanced +4 dBu). In order to open the console, you have to take out the entire board, not by channel strip. In doing this, I accidentally pulled some multipins in the midi section and placed them back where I *thought* they went. I consulted the service manual and I think everything looks right (there are some open pins). Well, the console turns on, but every channel mute light is on and when I press both the channel on and clip/listen buttons, the clip/listen led comes on. I should also note that the meters don't seem to respond to any input, and nothing seems to be functional. Does anybody have an idea as to where I should look?
 

73's de Edd

Aug 21, 2015
3,636
Joined
Aug 21, 2015
Messages
3,636
Sir apauly . . . . .

You say . . . . .
I accidentally pulled some multipins in the midi section and placed them back where I *thought* they went. I consulted the service manual and I think everything looks right (there are some open pins).


the resultant adverse affects were . . . .
Well, the console turns on, but every channel mute light is on and when I press both the channel on and clip/listen buttons, the clip/listen led comes on. I should also note that the meters don't seem to respond to any input, and nothing seems to be functional.

SPECIFICALLY . . .

Looks like the pins on MIDI BOARD CONN 9 would be most likely, the one to be associated with your mentioned maladies.
ANALYZING . . . the units CONN 9
Pin 1
. . . . . is + 15V DC power and Pin 2 is power ground, hopefully they were not ones being involved or else . . . . . ( ( KA-BOOOOOOOM ! ))
Pins 5 and 7 . . . . . are connected to feeble bias supplies associated with Interrup tand Reset functions into the M 50747 BITSUMISHI u/P that multiplexes all of the audio track channels , microseconds faster than your ear is even capable of perceiving. (50 millisecs detection threshold )
Pin 3 . . . . . is receiving digital output information from the u/P Port 6 that is fed to another area, you would have to trace that wire down to where it ends up and give feedback.
Pin 6 . . . . . is sending digital info to u/P Port 5 that comes in from another area, so you also need to track down that wire to the other section that it emanates from. This mosty likely would cause an overall mute fault. Ergo . . . VU meters no workee
SUMMATION . . . . .
Valid connections are made only into CONN 9 pins
1 . . . . . 15VDC power
2 . . . . . . Ground
3 . . . . . . Outputted digital signal from u/P Port 6.
5 . . . . . . Required +5 Interrupt bias for u/P
6 . . . . . . Required +5 Reset bias for u/P
7 . . . . . . Inputted digital signal going to u/P Port 5.


Now, tell us EXACTLY which pins you were involved with . . . . . . and what CONNectors were they on . . . . ? ? ?

MONITOR CIRCUIT

CONN 1
and its pins 3,4,5,6,7,8,9,10,11,12,13 and 14
CONN 2 and its pins 1,2,3,7,10,11 and 17
CONN 3 and its pins 3,5,6 and 7.


MIDI MUTE CIRCUIT . . . . . .( is being your mentioned problem board . . . . . ( ¿ and which CONNector pin(s) was / were being involved ? )

CONN 1 and its pins 1,2,3,4,5,6,7 and 8
CONN 2 and its pins 1,2,3,4,5,6,7,and 8
CONN 3 and its pins 1,2,3,4,5,6,7,and 8
CONN 4 and its pins 1,2,3,4,5,6,7,and 8
CONN 5 and its pins 1,2,3,4,5,6,7,and 8
CONN 8 and its pins 1,2,3,4,5,6,7 and 8
CONN 9 and its pins 1,2,3,5,6 and 7 . . . . . with its pins 4 and 9 having No Connections made into them . . . . . plus, also check that the 6 pins that are being connected into , are not now being miswired.

MIC CIRCUIT PART B

CONN 1
and its pins 1,2,3,4,5,6,7,8 ,9,10,11,12,13 and 14
CONN 3 and its pins 2,5,7,8,9,10,11 and 12

MIC CIRCUIT PART A

( If Fitted )
CONN 2 and its pins 1,2 and 3
CONN 4 and its pins 1,2 and 3
CONN 5 and its pins 1,2,3,4 and 5

LEFT-RIGHT OUTPUT CCT

CONN 1
and its pins 2,3,4 and 5
CONN 3 and its pins 2,4,7,10,11,12,14 and 16


Thaaaaaaaasssssssit . . . . .


73's de Edd . . . . .


My grandfather survived both mustard gas and pepper spray in the war.
You might say . . . . . . . He is a seasoned veteran now.


tenor.gif

.
 
Last edited:

apauly

Mar 8, 2023
2
Joined
Mar 8, 2023
Messages
2
Sir apauly . . . . .

You say . . . . .
I accidentally pulled some multipins in the midi section and placed them back where I *thought* they went. I consulted the service manual and I think everything looks right (there are some open pins).


the resultant adverse affects were . . . .
Well, the console turns on, but every channel mute light is on and when I press both the channel on and clip/listen buttons, the clip/listen led comes on. I should also note that the meters don't seem to respond to any input, and nothing seems to be functional.

SPECIFICALLY . . .

Looks like the pins on MIDI BOARD CONN 9 would be most likely, the one to be associated with your mentioned maladies.
ANALYZING . . . the units CONN 9
Pin 1
. . . . . is + 15V DC power and Pin 2 is power ground, hopefully they were not ones being involved or else . . . . . ( ( KA-BOOOOOOOM ! ))
Pins 5 and 7 . . . . . are connected to feeble bias supplies associated with Interrup tand Reset functions into the M 50747 BITSUMISHI u/P that multiplexes all of the audio track channels , microseconds faster than your ear is even capable of perceiving. (50 millisecs detection threshold )
Pin 3 . . . . . is receiving digital output information from the u/P Port 6 that is fed to another area, you would have to trace that wire down to where it ends up and give feedback.
Pin 6 . . . . . is sending digital info to u/P Port 5 that comes in from another area, so you also need to track down that wire to the other section that it emanates from. This mosty likely would cause an overall mute fault. Ergo . . . VU meters no workee
SUMMATION . . . . .
Valid connections are made only into CONN 9 pins
1 . . . . . 15VDC power
2 . . . . . . Ground
3 . . . . . . Outputted digital signal from u/P Port 6.
5 . . . . . . Required +5 Interrupt bias for u/P
6 . . . . . . Required +5 Reset bias for u/P
7 . . . . . . Inputted digital signal going to u/P Port 5.


Now, tell us EXACTLY which pins you were involved with . . . . . . and what CONNectors were they on . . . . ? ? ?

MONITOR CIRCUIT

CONN 1
and its pins 3,4,5,6,7,8,9,10,11,12,13 and 14
CONN 2 and its pins 1,2,3,7,10,11 and 17
CONN 3 and its pins 3,5,6 and 7.


MIDI MUTE CIRCUIT . . . . . .( is being your mentioned problem board . . . . . ( ¿ and which CONNector pin(s) was / were being involved ? )

CONN 1 and its pins 1,2,3,4,5,6,7 and 8
CONN 2 and its pins 1,2,3,4,5,6,7,and 8
CONN 3 and its pins 1,2,3,4,5,6,7,and 8
CONN 4 and its pins 1,2,3,4,5,6,7,and 8
CONN 5 and its pins 1,2,3,4,5,6,7,and 8
CONN 8 and its pins 1,2,3,4,5,6,7 and 8
CONN 9 and its pins 1,2,3,5,6 and 7 . . . . . with its pins 4 and 9 having No Connections made into them . . . . . plus, also check that the 6 pins that are being connected into , are not now being miswired.

MIC CIRCUIT PART B

CONN 1
and its pins 1,2,3,4,5,6,7,8 ,9,10,11,12,13 and 14
CONN 3 and its pins 2,5,7,8,9,10,11 and 12

MIC CIRCUIT PART A

( If Fitted )
CONN 2 and its pins 1,2 and 3
CONN 4 and its pins 1,2 and 3
CONN 5 and its pins 1,2,3,4 and 5

LEFT-RIGHT OUTPUT CCT

CONN 1
and its pins 2,3,4 and 5
CONN 3 and its pins 2,4,7,10,11,12,14 and 16


Thaaaaaaaasssssssit . . . . .


73's de Edd . . . . .


My grandfather survived both mustard gas and pepper spray in the war.
You might say . . . . . . . He is a seasoned veteran now.


tenor.gif

.
It was CONN9 and CONN7 that were pulled and then reseated. I should also note that during this time, the console was powered on (a mistake on my end). After taking some time to digest the schematic and the functions of each component, I suspect that the issue may possibly stem from the M50747 chip.
 

73's de Edd

Aug 21, 2015
3,636
Joined
Aug 21, 2015
Messages
3,636
Sir apauly . . . . .

Conn 7 is a minor consequence . . . . input.
The main one is Conn 9, and if it was left unplugged at power up, I can see no adverse consequences, with it being in an un powered state for that power on duration.
I was interpreting pins being pulled out of a connector and then being plugged in, but being unsure of where they were being re inserted, but not KNOWING, for sure, if being inserted in the right hole (s).
Your mentioned mere multiple plug in and unplug of a connector for "frictional cleaning" should pose no problem . . .if un powered..
If so then we know what pins were being involved . . . in order to visualize . . . . cause and effect . . . . if potentially being critical or nott.
That units OLD Bitsimishi u/ Processor is what you do NOT, want to be at fault with its internal CUSTOM designed 8k ROM specific only to its use in this application . It should fall in the UNOBTANIUM CATEGORY, unless an old good donor is able to be found. . . . IF it is at fault.
Voltage checks on that u/P would be its main power in of 5V at pin 1 and minor 5 V biases at pin 26 and after power up, and an initial reset pull down, pin 28 comes up to 5V.
Confirm those.

73's de Edd . . . . .
 
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