Repairs and Service
(Often designing backwards)
Many times we have been asked to repair equipment that was assumed to have failed. This has been over a wide range of technologies including digital, analog, numeric control, X-ray, score boards, motor drive systems etc. Unfortunately, in many cases the original design has been poor or not suitable for the work or the temperature to which it has been applied. In such cases we correct the design and if required, supply circuit diagrams.
We have also been asked to design and supply replacement circuit boards for obsolete equipment.
In one case the American 220v 3 phase power for an imported solar panel manufacturing machine was connected to the Australian 440vacin error. It was instant death. As the machine could not be replaced, we rebuilt all of the electronic components and power supplies for the insurance company. And yes, we did replace the control system with one using an embedded microprocessor!
Some Projects as Examples:
Totalizator Agency Board of Western Australia
We were asked by the TAB of WA if we could repair a circuit board shown to us. We said we could if weI had a circuit diagram, however none was available. We were then given the job to reverse engineer the IBM betting terminals. We prepared circuit diagrams for them and assisted the TAB of WA to set up their own service department. We subsequently repaired IBM circuit boards for the TAB, and designed and supplied lightning arrestors to reduce failures of the equipment in rural areas.
QV1 building management, Perth Western Australia
1) Due to Strand Electric going out of business, and being the suppliers of the architectural lighting system for the QV1 building, we were asked to finish commissioning the lighting system. Some of the PCB’s were damaged, and the lift regenerative breaking was making the lights flicker by losing mains sync. After adjustments to the PCB settings and repairs as required, the main light dimmers worked. However, the programming module for timing the lights to come on and off did not work properly. We designed a microprocessor control to replace this. Also, most of the lights being used were 110vac, but the mains was 240vac and the dimmers were only working at half power. Any malfunction fused the 110v lamps which necessitated the use of a ‘cherry picker’ to replace them. To prevent this happening we designed, built & installed ‘crow-bar’ PCB’s which, in the event of accidental over voltage, would blow the fuse in the dimmer module before the lamp failed,
Some of the light controls were of a different type, and could not be incorporated into the main timing programmer. We therefore designed and supplied a code converting PCB for D54 to AMX conversion using the 68HC705B16 processor.
2) We were asked to repair the circuit boards for the ‘touch’ operated toilet flushing system used in all the buildings toilets. They were having very high failure rates of both types of circuit boards used. On investigation we found the circuit design had fundamental errors. We then began modifying and repairing the hundreds of boards used, and also supplied replacement boards for those not able to be repaired. We are still repairing, modifying, and supplying boards to this day!
3) Modify microwave urinal flushing controllers for alternate flushing sequence.
4) Modify wind speed indicator to stop water flowing in ornamental fountain in high wind velocities. It had to be updated to digital technology from analog.
Basket Ball WA
We were asked to repair the newly installed score board at the Perry Lakes stadium. It soon became apparent that it had never worked properly from installation. The design had been rushed, and the suppliers had moved their operation offshore. Components had been wrongly specified, and under certain conditions of temperature, voltage, etc it would cease to operate. We replaced all relevant components with the correct type. This solved the sudden crash of the system, however, another problem still remained. When more than a certain number of digits were turned on, the display flickered madly. The problem was that the extra current through the zero volt rail upset the voltage thresholds for the logic IC’s. Rewiring the zero volt rail finally had it going properly.
We were later asked to design and supply a laptop PC to replace the original Z80 control box which was becoming too difficult to repair. All data entry was now via the laptop computer and much easier to use. We designed a serial interface module to run the score board display from the laptop.
Copyright Bernie Smith Electronics 2011. Site design and development by Sherwell Graphics