And welcome back to our project. Now, we are starting on the INPUT BOARD.
The RS Series Console used 6 Channel Input boards; we are going to do single channel boards, as I may opt for a 5-channel mixer rather than the 6-channel board we have been planning. More on that later.
The parts list below is for ONE Channel. You can multiply, right ? For those of you that went to U.C.F., get your neighbor kid to help. (Just kidding, no calls, please.)
Keep in mind that you can get many of these parts in bulk and SAVE, (See Chapter 2 - SETTING UP SHOP for some of my Ebay and Amazon buys) Use the Vendor List & Part numbers as a guide.
PARTS LIST
(NOTE: This is 'preliminary' and only for ONE input. I will post a final 'complete' parts list at the end of this blog. Also note that since this was prepared, ALL ELECTRONICS has closed their doors.)
Note: In my version I have changed J-9 (Mixer Control) from a 16 pin I.C. Socket to a 2x8 header. The same change will be used when I do the Input Controller Cards.
Note # 2: The P1086 transistor is OBSOLETE. I ordered some from Ebay, but I will also play around and see if I can come up with a substitute.
Note #3: The original VCA is also obsolete, but Radio Systems started using a different version that eliminated a resistor and changed the value of another. This change has been incorporated into our design.
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Let's look at the schematic.
Here is how the input board works. (Thanks to the Radio Systems manual)
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Six Channel Input Board Circuit Description Brief Description
7.2.1 Brief Description
The Six Channel Input Board contains six identical stereo amplifiers which provide the following:
1. selection of the input signal
2. gain adjustment of the input signal
3. routing of the selected signal to the desired mix buss or busses
7.2.2 Detailed Description
The left and right channels are identical, so only the left will be discussed.
Left channel input A signals are attenuated 13dB by Rl, R3, and R2 (or by R8, R7 and R9 for input B) before routing to IC Ul, a type 4052 analog switch. The amount of attenuation may be varied by the installation of resistors into the DIP component carriers (see below for discussion of the DIP attenuator's), and then plugging the DIP component carriers into socket J3 for input A or J4 for input B. Bridging R3 (or R9) would increase the attenuation while bridging Rl and R2 (or R8 and R7) would decrease the attenuation. Adjusting the attenuation allows each input to accept signals ranging from microphone to high level.
Integrated circuit Ul selects either input A or input B depending on the voltage present on pin U1-10. A low on pin 10 will allow input A signals to reach the following circuitry. Input B will
be selected if pin 10 is high. The voltage on pin10 is controlled by circuitry on the Input Control Board.
Integrated circuit U3 (sections A, B, and C) and transistors Ql and Q2 form a differentially balanced instrumentation amplifier for left channel input signals. Transistors Ql and Q2 are low
noise devices which allow this circuit to operate with microphone levels in addition to high level inputs.
Transistors Ql, Q2, and integrated circuits U3A and U3D form a balanced amplifier whose gain is determined by R28, R29 and R21. The gain may be increased by the installation of jumpers onto header J5 which would reduce the value of R21. A -7.5v reference is fed to the positive inputs of U3A and U3D which in turn control the current through Ql and Q2 so that the negative inputs of U3A and U3D also remain at -7.5v. This feedback makes Ql (Q2) a part of U3A (U3D) rather than an independent amplifier preceding the IC. Integrated circuit U3B is a differential amplifier which converts the balanced signal from U3A and U3D to a unbalanced signal.
The signal from U3B is summed with right channel signal from U4C and routed to Q7 which will place this mono signal onto the Cue Buss when the Q7 is turned on (by pulling its gate low) by the Input Control Board. In addition, the signal also is routed to J7, a stereo unbalanced insert point, as well as header J7, which allows bypassing of the patch point, and easy placement of a mixing channel into mono operation. In this case, the left input would feed both the left and the
right channel mix busses. The level at this point is nominally -4dBm. Integrated circuit U3C buffers the signal from the insert point prior to IC U6, a dBx Voltage Controlled Amplifier (VCA).
The VCA is a current in, current out device, which may provide amplification as well as attenuation of the signal from U3C. The VCA is capable of over 100 dB of level control,
depending upon the control voltage applied to pin 3 of the VCA. The front panel linear taper fader supplies a control voltage ranging from +7.5v at the minimum setting of the fader to 0 volts at the maximum setting. This voltage is applied to the positive input of U7B which serves as a buffer. Resistors R75 and R76 attenuate the buffered control voltage to levels acceptable by the VCA. Transistors Q5 and Q6 in conjunction with resistors R78 and R79 shunt R76 to convert the 50 linear fader taper into a three-slope audio taper approximation. The turn on points for Q5 and Q6 are determined by the fader setting and the voltage reference on the bases of Q5 and Q6. U7A and resistors R74 and R77 add a negative offset to the control voltage so that the VCA is at unity gain at normal fader settings and is supplying 15dB of gain at the maximum fader setting. In addition, U7A drives both left and right channel VCAs to maintain proper channel tracking. VR2 is the
VCA distortion null adjustment. Integrated circuit U8A converts the current output from the VCA into a voltage.
Integrated circuit U10 is a 4053 analog switch which connects the output of U8A to the mix busses as determined by voltages from the Input Control Board which are applied to U10 pins 6,
9, 10, and 11. Pin 6 must be low in order for the signal from U8A to reach any mix buss. Pulling pin 9 high (+7.5v), in conjunction with pulling pin 6 low, will place the signal from U8A onto the mono mix buss. Similarly, pulling pin 10 or pin 11 high will place the signal onto the audition and program mix buss respectively. Since pins 9, 10, and 11 operate Independently from each other, any combination of mix busses may be selected at the same time.
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DIP ATTENUATORS
The following chart shows how to build and use the DIP Attenuators, depending on the TYPE of input source you are using. It also shows how to set the Gain Pins on the input board. It is critical to the operation of the console. So do what I did. BUILD extras and have them on have in case you change input sources.
These are built on a carrier that fits the 14-pin I.C. socket J-3 & J-4. They WERE NOT included in the parts list, and I could not find what I used before. I did find some at 4-5 dollars each, but they were SPECIAL ORDER. So, we are trying the DH-14D from ALL Electronics. (Now that they are out of business, we need to find another source.
Carefully remove the top portion. You do not need it. Wire as the chart shows. With this part the resistors will be slanted a bit. But who cares? Right?
Here is my first attempt.
Now that we have a parts list, and reviewed how the board works, let's get to work on the SCHEMATIC.
Here is a schematic from the original manual.
And my version. (I split up my drawing, so it is more readable.)
NOTE: This is 'preliminary' I will post a final schematic version at the end of this blog.
Now that you have studied the drawing for three weeks, (It may take that long- I have been studying them for 10 years) let's move on to the CIRCUIT BOARD) And have a refreshing adult beverage.
YIPPEE!!! Hey, we are building a Radio Console, so the BEER MUG has to be radio themed. (Don't worry, I have more radio mugs. I'll save one for you.)
The board is straight forward. Take your time and CHECK CHECK CHECK those part clearances.
I am NOT ordering the boards until I have ALL the parts on hand so I can verify the clearances.
Keep working on the schematic and the board views, until you are 200% certain, there are NO mistakes.
Now you can order your parts, AND the boards.
Let's take a look.
And the board from JLCPCB
We have come to the point in our journey where we get to actually BUILD something.
That's next time.
Here is a 'sneak peek'.
See you then.
Here is the FINAL SCHEMATIC and PARTS LIST!!!! (This is for 1 INPUT)
PARTS LIST INPUT BOARD
COMPONENT TYPE DESIG. VALUE
CAPACITOR DISC C-001 100 PF
CAPACITOR DISC C-002 100 PF
CAPACITOR DISC C-003 100 PF
CAPACITOR DISC C-004 100 PF
CAPACITOR DISC C-005 100 PF
CAPACITOR DISC C-006 100 PF
CAPACITOR DISC C-007 100 PF
CAPACITOR DISC C-008 100 PF
CAPACITOR DISC C-017 22 PF
CAPACITOR DISC C-018 22 PF
CAPACITOR DISC C-019 22 PF
CAPACITOR DISC C-020 22 PF
CAPACITOR DISC C-021 47 PF
CAPACITOR DISC C-025 47 PF
CAPACITOR DISC C-032 47 PF
CAPACITOR DISC C-033 47 PF
CAPACITOR DISC C-031 .1 UF
CAPACITOR DISC C-037 .1 UF
CAPACITOR DISC C-051 .1 UF
CAPACITOR NON-POLARIZED C-035 100 UF 16V
CAPACITOR NON-POLARIZED C-036 100 UF 16V
CAPACITOR ELECTROLYTIC C-039 100 UF 25V
CAPACITOR ELECTROLYTIC C-046 1000 UF 10V
CAPACITOR ELECTROLYTIC C-047 1000 UF 10V
CAPACITOR ELECTROLYTIC C-048 1000 UF 10V
CAPACITOR ELECTROLYTIC C-049 1000 UF 10V
CAPACITOR NON-POLARIZED C-009 10 UF 25V
CAPACITOR NON-POLARIZED C-010 10 UF 25V
CAPACITOR NON-POLARIZED C-011 10 UF 25V
CAPACITOR NON-POLARIZED C-012 10 UF 25V
CAPACITOR NON-POLARIZED C-013 10 UF 25V
CAPACITOR NON-POLARIZED C-014 10 UF 25V
CAPACITOR NON-POLARIZED C-015 10 UF 25V
CAPACITOR NON-POLARIZED C-016 10 UF 25V
CAPACITOR NON-POLARIZED C-022 10 UF 25V
CAPACITOR NON-POLARIZED C-024 10 UF 25V
CAPACITOR NON-POLARIZED C-026 10 UF 25V
CAPACITOR NON-POLARIZED C-028 10 UF 25V
CAPACITOR NON-POLARIZED C-029 10 UF 25V
CAPACITOR NON-POLARIZED C-030 10 UF 25V
CAPACITOR NON-POLARIZED C-034 10 UF 25V
CAPACITOR NON-POLARIZED C-038 10 UF 25V
CAPACITOR NON-POLARIZED C-040 10 UF 25V
CAPACITOR NON-POLARIZED C-041 10 UF 25V
CAPACITOR NON-POLARIZED C-042 10 UF 25V
CAPACITOR NON-POLARIZED C-043 10 UF 25V
CAPACITOR NON-POLARIZED C-044 10 UF 25V
CAPACITOR NON-POLARIZED C-046 10 UF 25V
DIODE SWITCHING D-01 1N4148
DIODE SWITCHING D-02 1N4148
HEADER IDC J-010 26 PINS-DUAL ROWS
HEADER IDC J-011 26 PINS-DUAL ROWS
HEADER MOLEX J-012 15 PIN .1
HEADER MOLEX J-013 3 PIN .1
HEADER MOLEX J-014 3 PIN .1
HEADER MOLEX J-015 3 PIN .1
HEADER SCREW J-001 5 PIN
HEADER SCREW J-002 5 PIN
HEADER SCREW J-008 5 PIN
SOCKET DIP J-003 14 PIN
SOCKET DIP J-004 14 PIN
SOCKET DIP U3 SOCKET 14 PIN
SOCKET DIP U4 SOCKET 14 PIN
HEADER DUAL ROW J-005 6 PIN .1
HEADER DUAL ROW J-006 6 PIN .1
PLUG JUMPER J-005 2 PIN .1
PLUG JUMPER J-006 2 PIN .1
PLUG JUMPER J-007 2 PIN .1
HEADER SIP J-007 5 PIN SINGLE ROW .1
SOCKET IDC J-009 2 ROW 16 PINS
TRANSISTOR PNP Q-001 MPS4355
TRANSISTOR PNP Q-002 MPS4355
TRANSISTOR PNP Q-003 MPS4355
TRANSISTOR PNP Q-004 MPS4355
TRANSISTOR PNP Q-005 MPS4355
TRANSISTOR PNP Q-006 MPS4355
TRANSISTOR FET Q-007 P-1086
RESISTOR FILM R-013 1.0 MEG ¼ WATT 1 %
RESISTOR FILM R-014 1.0 MEG ¼ WATT 1 %
RESISTOR FILM R-015 1.0 MEG ¼ WATT 1 %
RESISTOR FILM R-016 1.0 MEG ¼ WATT 1 %
RESISTOR FILM R-017 1.0 MEG ¼ WATT 1 %
RESISTOR FILM R-018 1.0 MEG ¼ WATT 1 %
RESISTOR FILM R-019 1.0 MEG ¼ WATT 1 %
RESISTOR FILM R-020 1.0 MEG ¼ WATT 1 %
RESISTOR FILM R-001 7.87 K ¼ WATT 1 %
RESISTOR FILM R-002 7.87 K ¼ WATT 1 %
RESISTOR FILM R-004 7.87 K ¼ WATT 1 %
RESISTOR FILM R-005 7.87 K ¼ WATT 1 %
RESISTOR FILM R-007 7.87 K ¼ WATT 1 %
RESISTOR FILM R-008 7.87 K ¼ WATT 1 %
RESISTOR FILM R-010 7.87 K ¼ WATT 1 %
RESISTOR FILM R-011 7.87 K ¼ WATT 1 %
RESISTOR FILM R-021 5.11 K ¼ WATT 1 %
RESISTOR FILM R-028 5.11 K ¼ WATT 1 %
RESISTOR FILM R-029 5.11 K ¼ WATT 1 %
RESISTOR FILM R-035 5.11 K ¼ WATT 1 %
RESISTOR FILM R-039 5.11 K ¼ WATT 1 %
RESISTOR FILM R-040 5.11 K ¼ WATT 1 %
RESISTOR FILM R-049 5.11 K ¼ WATT 1 %
RESISTOR FILM R-050 5.11 K ¼ WATT 1 %
RESISTOR FILM R-056 5.11 K ¼ WATT 1 %
RESISTOR FILM R-057 5.11 K ¼ WATT 1 %
RESISTOR FILM R-022 1580 OHMS ¼ WATT 1 %
RESISTOR FILM R-038 1580 OHMS ¼ WATT 1 %
RESISTOR FILM R-023 365 OHMS ¼ WATT 1 %
RESISTOR FILM R-036 365 OHMS ¼ WATT 1 %
RESISTOR FILM R-024 19.1 OHMS ¼ WATT 1 %
RESISTOR FILM R-037 19.1 OHMS ¼ WATT 1 %
RESISTOR FILM R-026 10.2 K ¼ WATT 1 %
RESISTOR FILM R-027 10.2 K ¼ WATT 1 %
RESISTOR FILM R-033 10.2 K ¼ WATT 1 %
RESISTOR FILM R-034 10.2 K ¼ WATT 1 %
RESISTOR FILM R-043 10.2 K ¼ WATT 1 %
RESISTOR FILM R-045 10.2 K ¼ WATT 1 %
RESISTOR FILM R-047 10.2 K ¼ WATT 1 %
RESISTOR FILM R-048 10.2 K ¼ WATT 1 %
RESISTOR FILM R-055 10.2 K ¼ WATT 1 %
RESISTOR FILM R-061 10.2 K ¼ WATT 1 %
RESISTOR FILM R-064 10.2 K ¼ WATT 1 %
RESISTOR FILM R-065 10.2 K ¼ WATT 1 %
RESISTOR FILM R-081 10.2 K ¼ WATT 1 %
RESISTOR FILM R-030 28.0 K ¼ WATT 1 %
RESISTOR FILM R-031 28.0 K ¼ WATT 1 %
RESISTOR FILM R-041 28.0 K ¼ WATT 1 %
RESISTOR FILM R-042 28.0 K ¼ WATT 1 %
RESISTOR FILM R-032 10 K ¼ WATT 1 %
RESISTOR FILM R-086 10 K ¼ WATT 1 %
RESISTOR FILM R-087 10 K ¼ WATT 1 %
RESISTOR FILM R-093 10 K ¼ WATT 1 %
RESISTOR FILM R-095 10 K ¼ WATT 1 %
RESISTOR FILM R-099 10 K ¼ WATT 1 %
RESISTOR FILM R-100 10 K ¼ WATT 1 %
RESISTOR FILM R-101 10 K ¼ WATT 1 %
RESISTOR FILM R-102 10 K ¼ WATT 1 %
RESISTOR FILM R-103 10 K ¼ WATT 1 %
RESISTOR FILM R-003 5.76 K ¼ WATT 1 %
RESISTOR FILM R-006 5.76 K ¼ WATT 1 %
RESISTOR FILM R-009 5.76 K ¼ WATT 1 %
RESISTOR FILM R-012 5.76 K ¼ WATT 1 %
RESISTOR FILM R-044 20 K ¼ WATT 1 %
RESISTOR FILM R-062 20 K ¼ WATT 1 %
RESISTOR FILM R-084 20 K ¼ WATT 1 %
RESISTOR FILM R-085 20 K ¼ WATT 1 %
RESISTOR FILM R-046 392 OHM ¼ WATT 1 %
RESISTOR FILM R-063 392 OHM ¼ WATT 1 %
RESISTOR FILM R-051 4.75 K ¼ WATT 1 %
RESISTOR FILM R-058 4.75 K ¼ WATT 1 %
RESISTOR FILM R-078 4.75 K ¼ WATT 1 %
RESISTOR FILM R-052 4.02 K ¼ WATT 1 %
RESISTOR FILM R-059 4.02 K ¼ WATT 1 %
RESISTOR FILM R-066 4.02 K ¼ WATT 1 %
RESISTOR FILM R-072 4.02 K ¼ WATT 1 %
RESISTOR FILM R-053 1.2 K ¼ WATT 1 %
RESISTOR FILM R-054 100 K ¼ WATT 1 %
RESISTOR FILM R-060 100 K ¼ WATT 1 %
RESISTOR FILM R-067 220 K ¼ WATT 1 %
RESISTOR FILM R-071 220 K ¼ WATT 1 %
RESISTOR FILM R-080 100 K ¼ WATT 1 %
RESISTOR FILM R-091 100 K ¼ WATT 1 %
RESISTOR FILM R-092 100 K ¼ WATT 1 %
RESISTOR FILM R-094 100 K ¼ WATT 1 %
RESISTOR FILM R-068 15 K ¼ WATT 1 %
RESISTOR FILM R-069 15 K ¼ WATT 1 %
RESISTOR FILM R-069 NOT USED
RESISTOR FILM R-073 NOT USED
RESISTOR FILM R-074 187 K ¼ WATT 1 %
RESISTOR FILM R-075 2.21 K ¼ WATT 1 %
RESISTOR FILM R-077 2.21 K ¼ WATT 1 %
RESISTOR FILM R-076 68.1 K ¼ WATT 1 %
RESISTOR FILM R-079 47.5 K ¼ WATT 1 %
RESISTOR FILM R-082 27.4 K ¼ WATT 1 %
RESISTOR FILM R-083 27.4 K ¼ WATT 1 %
RESISTOR FILM R-088 2.0 K ¼ WATT 1 %
RESISTOR FILM R-089 2.0 K ¼ WATT 1 %
RESISTOR FILM R-090 2.0 K ¼ WATT 1 %
RESISTOR FILM R-096 2.0 K ¼ WATT 1 %
RESISTOR FILM R-074 2.0 K ¼ WATT 1 %
RESISTOR FILM R-098 2.0 K ¼ WATT 1 %
RESISTOR FILM R-104 2.0 K ¼ WATT 1 %
RESISTOR FILM R-105 2.0 K ¼ WATT 1 %
RESISTOR FILM R-106 2.0 K ¼ WATT 1 %
RESISTOR FILM R-107 2.0 K ¼ WATT 1 %
RESISTOR FILM R-108 2.0 K ¼ WATT 1 %
RESISTOR FILM R-109 2.0 K ¼ WATT 1 %
I.C. SWITCH U-01 CD-4052
I.C. SWITCH U-02 CD-4052
SOCKET U-01 SOCKET
SOCKET U-02 SOCKET
SOCKET U-09 SOCKET
SOCKET U-10 SOCKET
I.C. OP AMP U-03 LF347
I.C. OP AMP U-04 LF347
I.C. VCA U-05 DBX 2180A
I.C. VCA U-06 DBX 2180A
SOCKET SIP U-05 SOCKET 8 PIN
SOCKET SIP U-06 SOCKET 8 PIN
I.C. OP AMP U-07 4558
SOCKET DIP U-07 SOCKET 8 PIN
SOCKET DIP U-08 SOCKET
I.C. OP AMP U-08 SOCKET NE5532
I.C. SWITCH U-09 4053
I.C. SWITCH U-10 4053
POTENTIOMETER TRIM VR1 50K
VR2 50K
God Speed, Mother Nature.
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