NOTES FOR THE FOLLOWING "MicroAudio BUS" PRODUCTS
The following models are "MicroAudio BUS" products:
1) Altec Lansing 8551A/B
2) Altec Lansing 8558A/B
3) Altec Lansing 8553B
4) MicroAudio EQ POD 1.1A/B
5) MicroAudio EQ POD 1.2B
6) MicroAudio EQ POD 2.1B
7) MicroAudio EQ POD 2.2B
8) MicroAudio EQ POD 3.1
9) MicroAudio EQ POD 3.2
In the 1980s MicroAudio sold a line of programmable equalizers and attenuators that were controlled via our "MicroAudio BUS".
At the time laptop computers were not readily available so we developed our own proprietary data interface. This serial data interface is NOT an RS232 connection, hence will not connect to the serial port on the back of your computer.
We developed a series of programmers that the contractor could take into the field. Programming Devices equipped with the MicroAudio BUS:
1) the RTA/Programmers, Altec Lansing 8051A and MicroAudio 2800 (same unit different name brand)
2) the handheld programmers, Altec Lansing 8055A/B and MicroAudio Model 28R (same unit different name brand)
3) full length ISA card, Altec Lansing 8061and MicroAudio PC280 (same unit different name brand)
4) 28 slider adjustable programmer, MicroAudio GPX280
There was one box that could accept RS232 signals from the serial port on a laptop and output the MicroAudio BUS. This was the Altec Lansing 8063 and MicroAudio SCOM1.0. If you do not have a programming box for the MicroAudio BUS equalizers, these are available for rent from MicroAudio.
Connection for the Programmer and the EQ POD:
On all models of programmers except the Model 28R/ 8063 always power up both the EQ and the programmer first before connecting the programming cable.
After both units are powered up, connect the programming cable, program the EQ, then disconnect the cable while both units are powered up.
On the Model 28R/ 8063 connect the cable when the EQ POD is turned off. The Model 28R/ 8063 derive their power from the EQ POD. With the power off, connect the programming cable, power up both the programmer and the EQ POD and program the EQ POD with your settings.
Power down both, then disconnect the cable.
All products using the MicroAudio BUS used the same cable. This cable has a band of black heat shrink tubing on one end.
The cable connection is as follows:
| PROGRAMMER | EQ POD |
| pin 1 Clock Low | pin 1 Data |
| pin 2 Strobe Low | pin 2 Clock Low |
| pin 3 Data | pin 3 Strobe Low |
| pin 4 Clock High | pin 4 Clock High |
| pin 5 Strobe High | pin 5 Strobe High |
| pin 6 Shield Ground | pin 6 Shield Ground |
| pin 7 +5V | pin 7 +5V |
| pin 8 Read/Write Line | pin 8 Read/Write Line |
| pin 9 Ground | pin 9 Ground |
The EQ POD was always a DB9 female and the programmer was always a DB9 male.
Note that pins 4 through 9 are straight through, but pins 1 to 3 are mixed.
For instance, pin 1 on the programmer goes to pin 2 on the EQ POD, etc.
If you are making up this cable be sure to place a band of black heat
shrink around the cable (or electrical tape).
This will indicate that it is an EQ POD programming cable.
NOTES FOR THE RS232 EQ POD PRODUCTS
If you have one of the following products please read this service note:
EQ POD 1.6CQ or 1.6VQ
EQ POD 2.6CQ or 2.6VQ
EQ POD 1.0CQ or 1.0VQ
EQ POD 2.0CQ or 2.0VQ
EQ POD 1.2CQ or 1.2VQ
EQ POD 2.2CQ or 2.2VQ
Altec Lansing 8431 or 8432
IRP PCEQ 281 or 282
We have found that in noisy AC ground situations,
noise spikes can disrupt function of the microprocessor.
Symptoms of this condition are intermittent loss of audio as well as loss of the front panel LED(s) and
powering down then up the unit will restore the EQ to normal function.
If this symptom exists then
please check that there is a ground strap on the 7 pin audio connector between chassis and signal ground.
If this does not fix the problem then take the unit to a local dealer.
They will make sure that the following is done:
They will check that your unit does NOT have 2 AC filter capacitors on the power supply line of the power supply board.
They will find these capacitors located directly behind the 110/220VAC IEC power connector on the power supply board.
Please do not do this surgery yourself because line voltages exist and you can be shocked.
You should never remove the lid of the unit; this should be done by a qualified service technician.
If the technician finds there is 1 capacitor your unit is OK.
If there are 2 capacitors then your dealer will:
a) They will disconnect power from unit and remove lid.
b) They will check AGAIN that the power cord is disconnected from unit.
c) They will clip out the 2 yellow capacitors directly behind 110VAC IEC power connector and throw them away.
d) They will replace lid... Problem solved!