STA Compact Electrical Block Diagram of the CPU

Tutorial on the computer section of the STA compact.

Transcription of STA Compact Electrical Block Diagram of the CPU

Welcome back to Bio Med Buddy. Today we are going to talk about the computer section in the STA Compact. First let's go through the list of components. All of these components are located in the PC rack on the left-hand side of the instrument. (Slide Change :20) This is a reminder, to get to the PC rack, you pry off the four little buttons on each corner, unscrew the screw, and the side of the unit goes straight up and is removable. After that there are four screws that go into a steel plate. If you remove that steel plate which gives you access to the PC rack.

From there, remove four screws and you'll have access to all of the components inside the PC rack which consist of; (Slide Change :42) an 8 slot backplane board, a 486 PC board, a 4-port serial board, possibly a VGA board, a hard disk drive, a cable going to the hard disk drive, one input/output control board, and a cable going to the floppy disk drive.

The main function of this unit, it simply handles all of the STA Compact software, communicates with the user through the use of the keyboard and the monitor. (Slide Change 1:10) Now let's go through each board individually. We're going to start out with the 8 slot backplane which uses the following power supplies along with the rest of the boards within the PC rack which are; the 5 volts, the plus 12 volts, and the negative 12 volts. On the 8 slot backplane board, you will see 3 dials that indicate all of these power supplies are OK. D1 is the 5 volts. D2 is the plus 12. D3 is the negative 12. I have never seen any issues with the 8 slot backplane board. It simply communicates between the 486 on the input-output control board, the 4-port serial board, and possibly the VGA board.

Now on to the 486 PC board. Again, it uses the same power supplies; plus 5 volts, plus 12 volts, and negative 12 volts. Most of them have a controller for your VGA monitor. It also has a controller for the hard disk drive, and the floppy disk drive, and it ensures a serial link for their host computer, your LIS system. For the most part, if the CPU 486 PC board fails, nothing in the instrument works. You will not get a boot up, probably no monitor, or no keyboard action. Sometimes the monitor section, the VGA controller, can fail on itself. Sometimes the controller to the hard disk can fail on its own.

Simple test for that is to see if the instrument boots up. If it boots up and you get a DOS prompt, you can pretty much assure that your 486 PC board is working OK, which leads you to the hard disk drive, pretty much an off the shelf hard drive and it controls STA software, and then the DOS 6.2 software. In general, by taking the cable and changing the connector on the cable, and going to the setup, the BIOS setup, you can change this unit so that it will boot up using the floppy disk drive. Put in the 6.2 software, run ScanDisk. If ScanDisk works fine, you can assume that your hard disk drive is OK. You can also put in a service disk and go directly to ScanDisk through the DOS prompts; which you get to by going to the service menu. We will discuss that at a later point.

Now, onto the 4-port serial board, (Slide Change 3:30) the 4-port serial board communicates through series connectors to the following boards; 4 axis board, measurement CPU board, positive identification board, and the DC motors control board. Port 1 is for the 4 axis board. Port 2 is the measurement
CPU. Port 3 is the positive identification, port 4, DC motors. You can see all of these ports through the picture on the right-hand side of this program. The 4-port serial board communicates to the 4 axis board using port 1, com 2, communicates to the measurement CPU board using port 2, com 3, and communicates to the positive identification board using port 3, com 4, communicates to the DC motors using port 4, com 5.

The 4-port serial board, in general, when it fails, your monitor will still work although it may be very slow because the CPU is trying to communicate with another section of the instrument such as the 4 axis
board, measurement CPU, the positive identification board, or the DC motors. So it generally works slower. If you can type on the keyboard and a general DOS prompt comes up, but you get a communication error, the 4- port serial board would be a suspect.

In general, as a clue, a lot of times when you check out the 4-port serial board using the service menu, you'll find that everything doesn't quite work like you expect. You see no proms being addressed in the identification boards. You see it will not map things of this nature. It's pretty much cut and dry, where the monitor works, the keyboard seems to work, but you get a timeout or a communication error of some sort, but it pretty much downs the instruments. Generally, it's not an intermittent issue, but I have seen it at times be somewhat intermittent, but for the most part repeatable. Point being, most of the time, it's an obvious failure of the 4-port serial board. (Slide Change 5:31)

Input/output control board, it uses the 5 volts power supply. It communicates between the 486 PC board and the input/output board. It also generates signals for the valve core pump along with several signals for different input/output board buffers. I/O card, when it fails, most of the time you'll get multi-failures. Sometimes it's hard to see because the monitor will only display the first error that comes up. The typical one I would see, would be something that would be abnormal, would be the front door being not in place and once if you cleared that, right after that, you would see the fluidic valves being missed, and if you resolve that in some manner, you'd see the next error. That's generally an indication of the I/O control board. In other words, multi input and output devices are failing. Again, that is somewhat hard to see because of just the nature of how the instrument runs. Thank you very much for attending this session of a biomed training program on the STA compact.