Hello everybody !
I am hobbyist trying to resurrect something which is out of my league. But I want to try .....
I got hold of 3 ATEN kvm switches. They are a switching device to switch between multiple computers with only single Keyboard/Mouse/Monitor. All of them have a problem. Their mouse ports dont work. The PC starts but at the BIOS it says "Mouse not found". Other ports do switch keyboard and VGA.
After rebooting many times thinking it might reset the switch I gave up. I tried different mouse models but to no avail. I then checked the voltages at the PS/2 mouse output port, pin number 5 (clock) and 1 (data) were oscillating with 5v max. Pin 4 also has 5v but it is steady. I cross checked from a fully functional PC, whose mouse PS/2 port (pins 5,1,4) voltages were a steady 5v.
I recapped the entire device thinking power quality might be a problem but the problem of oscillating voltages remained. I also check a nearby transistor with a component tester, but it was found to be normal. There is an IC nearby. It has been sanded down so I dont know its identity. But Mr Google search showed me what it might be.I think the chip is PIC16F72. I might have got it wrong but I dont know. It is same 28 pins and the dimensions are the exact same. I checked continuity with a DMM, IC Pin 2 and 3 have a direct line to the problematic PS/2 mouse port (pin 5 and pin 1). Voltage oscillation can be seen here too.
The functional keyboard port doesnt connect to this IC so it isnt affected.
What do you think ? Can the mouse ps/2 ports be made working again ?
Do you think the IC has gone bad ? If its a PIC16F72 and I get a new one, even then without the code its no use.
Can the problem be elsewhere making the chip behave bad ? I couldnt understand what to check next.
Thanks
Prashanth
I am hobbyist trying to resurrect something which is out of my league. But I want to try .....
I got hold of 3 ATEN kvm switches. They are a switching device to switch between multiple computers with only single Keyboard/Mouse/Monitor. All of them have a problem. Their mouse ports dont work. The PC starts but at the BIOS it says "Mouse not found". Other ports do switch keyboard and VGA.
After rebooting many times thinking it might reset the switch I gave up. I tried different mouse models but to no avail. I then checked the voltages at the PS/2 mouse output port, pin number 5 (clock) and 1 (data) were oscillating with 5v max. Pin 4 also has 5v but it is steady. I cross checked from a fully functional PC, whose mouse PS/2 port (pins 5,1,4) voltages were a steady 5v.
I recapped the entire device thinking power quality might be a problem but the problem of oscillating voltages remained. I also check a nearby transistor with a component tester, but it was found to be normal. There is an IC nearby. It has been sanded down so I dont know its identity. But Mr Google search showed me what it might be.I think the chip is PIC16F72. I might have got it wrong but I dont know. It is same 28 pins and the dimensions are the exact same. I checked continuity with a DMM, IC Pin 2 and 3 have a direct line to the problematic PS/2 mouse port (pin 5 and pin 1). Voltage oscillation can be seen here too.
The functional keyboard port doesnt connect to this IC so it isnt affected.
What do you think ? Can the mouse ps/2 ports be made working again ?
Do you think the IC has gone bad ? If its a PIC16F72 and I get a new one, even then without the code its no use.
Can the problem be elsewhere making the chip behave bad ? I couldnt understand what to check next.
Thanks
Prashanth
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