Hi,
I am attempting a repair on a firewire device which uses chips TSB81BA3 and tsb82aa2. The device has two firewire 800 ports and one firewire 400 port, so all ports on the TSB81BA3 are broken out to connectors.
When I plug a firewire cable into the device, which is plugged into a firewire PCI interface on a computer, the computer never detects the presence of a firewire device. I don’t know enough about firewire to know if both the TSB81BA3 and tsb82aa2 must both be functioning correctly for the device to be detected by the computer or just the TSB81BA3 transceiver?
I have listed all of the state conditions below for the pins of the TSB81BA3. Linking a firewire port to a computer does not change the state of any of the pins below except the voltages at TPA/B (my biggest suspicion something is not working properly). The TPA+/- are pulled low to 0.07V and TPB+/- pins are presented with 3.3V from the computer which is pulled down to 0.14V when the cable is connected.
PLLVSS and DVDD-Core voltages are correct
XI=98.304MHz VOH and VOL within correct range
PD=0
BMODE=1
TPA+/- 1.71V
R0-R1 = 6.37K
DS0=1k to GND
DS1=220r to GND
TESTM=1k to Vdd
TESTW=1k to Vdd
SE=1k to GND
SM=1k to GND
PC0=GND
PC1=GND
PC2=GND
CTL0=0
CTL1=0
PCLK=0 (this should be active since 0.22uS and 2.4uS shorter than 26uS LPS_DISABLE time?)
LCLK=0
LKON/DS2=0
RSVD=98.304MHz 25mV pk-pk (should be 3.3V pk?)
CNA=1 (This should change when linked to a computer firewire PCI card?)
CPS=GND
PD=0
RESETZ=1
LREQ=0
PINT=0
D0-7=0
LPS=0.23uS on, 0.22uS off
=2.4uS on, 2.4uS off
(LPS input sometimes 1x and other times, 10x frequency)
I would appreciate any help. I think the parts in bold above show a faulty chip or something else? The chip is new so should be ok.
Kind Regards,