2PAC Mafia
Member
Hi guys,
we are working on a marine ECU which uses MC68332 processor. The problem we are trying to repair is about CAN bus output missing. The processor communicates by 8 bits bus to this QE82527 CAN bus driver. When you switch on the power all is working fine, it boots correctly and shows alarm codes on small LCD display, but the problem is that it should show CAN bus communication and it is not showing any output from its driver.
The steps we did in all the troubleshooting were:
- Replace QE82527 (twice)
- Check TX-RX output impedance on QE82527
- Check data and address bus continuity and wave form from processor-memories and driver chip
- Check with logic analyzer the bus address and data at QE82527, comparing with a good unit we saw a difference at some data, beginning with the first address which was READ and following with some WRITE data.
- Check with different EEPROM firmware with same behavieur
- Reprogram offline EEPROM memories to check correct bus microprocessor to memories behavieur successfully accessing by RS232 port
- Replace RAM chips
- Check QE82527 port 2 and compare successfully with a good one correctly
- Check QE82527 oscillator circuit correctly
- Replace main microprocessor MC68332
- Resold and check for frozen soldering points at memories
Our main doubt is why with the logic analyzer we see a different behavieur in data bus comparing from bad unit to good unit when we want to check the registers configuration signals commanded by the processor to the QE82527, during that chip select access. We see how the processor is not really configuring the chip so we have not output communication data.
Any idea is welcome. We attach main datasheets. Thanks a lot.
we are working on a marine ECU which uses MC68332 processor. The problem we are trying to repair is about CAN bus output missing. The processor communicates by 8 bits bus to this QE82527 CAN bus driver. When you switch on the power all is working fine, it boots correctly and shows alarm codes on small LCD display, but the problem is that it should show CAN bus communication and it is not showing any output from its driver.
The steps we did in all the troubleshooting were:
- Replace QE82527 (twice)
- Check TX-RX output impedance on QE82527
- Check data and address bus continuity and wave form from processor-memories and driver chip
- Check with logic analyzer the bus address and data at QE82527, comparing with a good unit we saw a difference at some data, beginning with the first address which was READ and following with some WRITE data.
- Check with different EEPROM firmware with same behavieur
- Reprogram offline EEPROM memories to check correct bus microprocessor to memories behavieur successfully accessing by RS232 port
- Replace RAM chips
- Check QE82527 port 2 and compare successfully with a good one correctly
- Check QE82527 oscillator circuit correctly
- Replace main microprocessor MC68332
- Resold and check for frozen soldering points at memories
Our main doubt is why with the logic analyzer we see a different behavieur in data bus comparing from bad unit to good unit when we want to check the registers configuration signals commanded by the processor to the QE82527, during that chip select access. We see how the processor is not really configuring the chip so we have not output communication data.
Any idea is welcome. We attach main datasheets. Thanks a lot.
