»

[Bokasa]

I need help. Mouse at my A4000T stoped. I cant move pointer, but mouse buttons working OK. Mouse is OK (I tried at another Amiga) and I/O daughterboard is OK (I have spare one). So something died at MoBo, and I dont know what. Everything working good, including keyboard and I can move pointer with A button+cursors, but not with mouse. Is there any idea???
Thanks

[Tahoe]

Sounds like a CIA...

[Bokasa]

Originally Posted by Tahoe

Sounds like a CIA...

CIA or Paula?

[JimS]

Usually that means that there's no 5v on the mouse port. On the newer 2000's there's a fuse. I don't know about the 4000T. If you have a volt meter, you can check the joystick port for 5v. If I remember rightly, it's the middle two pins on the bottom row.

<------ 1000th post!

[Dr.Bongo]

http://www.rabayjr.com/Amiga/Flyer_F.../mousdead.html

[Castellen]

Originally Posted by Bokasa

CIA or Paula?

Unlikely to be a CIA fault as this only reads the left mouse button/fire input, nothing to do with movement input despite some common misunderstanding. You've already said the mouse buttons work OK.

Unlikely to be a fault of Paula as this device only reads in the four analogue paddle inputs (including right mouse button). Again, you've said the buttons work.

Checking that the +5V supply is active is a good suggestion. This is on pin 7 of both 9-way connectors. You can use a bare metal part of the chassis or pin 8 of the mouse/joystick connector as a ground/0V reference.

In the A4000T this 5V supply is via polyswitch fuse F160 on the main board. It's located on the edge of the board, between Paula and the keyboard connector. These devices are essentially PTC thermistors in that they're near short circuit under normal conditions. When fault current flows, they get hot and exhibit a high resistance, thus limiting current. They revert to a normal low resistance state when the fault current is cleared and the device cools, hence they're often called self-resetable fuses.

If your main board is an A4000D (in a tower case), the 5V supply for the mouse/joystick ports is via polyswitch fuse F175, which is the large yellow disc shaped device behind the serial/Centronics ports.

If it's an A4000D that has had major RTC battery corrosion damage, it's often shift register U975 at fault that causes no mouse movement.

I wrote this article on mouse port repair which may help further.

[Bokasa]

Originally Posted by Castellen

Unlikely to be a CIA fault as this only reads the left mouse button/fire input, nothing to do with movement input despite some common misunderstanding. You've already said the mouse buttons work OK.

Unlikely to be a fault of Paula as this device only reads in the four analogue paddle inputs (including right mouse button). Again, you've said the buttons work.

Checking that the +5V supply is active is a good suggestion. This is on pin 7 of both 9-way connectors. You can use a bare metal part of the chassis or pin 8 of the mouse/joystick connector as a ground/0V reference.

In the A4000T this 5V supply is via polyswitch fuse F160 on the main board. It's located on the edge of the board, between Paula and the keyboard connector. These devices are essentially PTC thermistors in that they're near short circuit under normal conditions. When fault current flows, they get hot and exhibit a high resistance, thus limiting current. They revert to a normal low resistance state when the fault current is cleared and the device cools, hence they're often called self-resetable fuses.

If your main board is an A4000D (in a tower case), the 5V supply for the mouse/joystick ports is via polyswitch fuse F175, which is the large yellow disc shaped device behind the serial/Centronics ports.

If it's an A4000D that has had major RTC battery corrosion damage, it's often shift register U975 at fault that causes no mouse movement.

I wrote this article on mouse port repair which may help further.

This is A4000T Escom board. I have 5V at pin 1,2,3,4,6 and I have 3.96V at pin 5 and 9, but I dont have 5V at pin 7. F160 seem to be OK, not hot and short circuit. I also have 5V at both side of F160.
Thank you for help.

[Calgor]

@ Bokasa

Interesting that only your mouse port does not get the user5V on pin 7. My A4000T board has the problem where if it is slightly bent one way near the keyboard connector/F160 the user5V goes either low or completely from both the mouse and the keyboard and the whole computer stops working (slight bend the opposite way makes it work), unplugging keyboard usually fixes it. So different problem to mine but similar in that you have a problem with the user5v part of the circuit somewhere.

If you do not have the keyboard plugged in, does the mouse work? Just something to try that mostly works for me when my problem occurs.

@ Castellen

Good tips.

[Gilthanaz]

Hi!

I had the exact same issue on my A1200 (Mouse buttons worked, but no analog paddle status at all) and took it completely apart without finding any issues, including measuring voltages and what-not.

What fixed it for me was to plug in a Joystick to the mouseport (with machine running), move it around wildly, unplug the Joystick and plug in the mouse again.

And it works again. Give it a shot, might just work as it did for me.

KR,
- G

[Castellen]

Originally Posted by Bokasa

This is A4000T Escom board. I have 5V at pin 1,2,3,4,6 and I have 3.96V at pin 5 and 9, but I dont have 5V at pin 7. F160 seem to be OK, not hot and short circuit. I also have 5V at both side of F160.

That certainly looks like the problem then, the mouse needs the 5V supply to operate. So just in case the wild joystick movement in the mouse port doesn't resolve it for you, the logical step is to trace the connections between pin 7 of the mouse/joystick port back to F160. i.e. with the computer powered off, use an ohmmeter to check continuity from pin 7 back to F160.

There probably isn't much in between aside from those 40-way ribbon cables (does the Escom board have these the same as the AT version?) and perhaps a ferrite bead. Don't rule out intermittent IDC connectors on the ribbon cables, though the 5V supply is fed in parallel from both cables so both would have to develop a problem for the 5V to dissappear, which would be uncommon.

The schematic of the ports board is here and the appropriate section of the main board is here. Sorry about the lack of quality in those scans, my original paper copies looked to have been photocopied and reduced several times over, so that's as good as you'll get.

[Gilthanaz]

Additional note:
When i measured the voltages back then they also did not be anything near the specifications i found, including one pin that was 'dead' even tho it should have had voltage on it. Unfortunately i did not keep the notes from the test, which i will definitly do the next time this happens. Basically from what i've learned that documentation is possibly outdated or not valid for all motherboard revisions. Then again i only had one A1200 to test with and i'am overall not much of a hardware chief

Just saying to possibly not trust those voltages that you are supposed to measure, they also were different for me. If i remember correctly, i wasted about an hour pondering the pin layout because that one pin would simply not give any voltage when the documentation said it should...

Oh, and btw, if you plug in the Joystick (tho iam pretty sure you know that) to the mouse port, and move it around, the cursor should go "wiggly" if there is any signal coming through...

KR,
- G

[mechy]

Originally Posted by Bokasa

I need help. Mouse at my A4000T stoped. I cant move pointer, but mouse buttons working OK. Mouse is OK (I tried at another Amiga) and I/O daughterboard is OK (I have spare one). So something died at MoBo, and I dont know what. Everything working good, including keyboard and I can move pointer with A button+cursors, but not with mouse. Is there any idea???
Thanks

i could be completely wrong here,but iirc one of the buttons on the 4000t escom models locks the mouse when on(or off?)? i hope i am remembering this right. Maybe its the keylock i am thinking of...

might be a good idea to check them and the connections

Mech

[Bokasa]

Originally Posted by Castellen

That certainly looks like the problem then, the mouse needs the 5V supply to operate. So just in case the wild joystick movement in the mouse port doesn't resolve it for you, the logical step is to trace the connections between pin 7 of the mouse/joystick port back to F160. i.e. with the computer powered off, use an ohmmeter to check continuity from pin 7 back to F160.

There probably isn't much in between aside from those 40-way ribbon cables (does the Escom board have these the same as the AT version?) and perhaps a ferrite bead. Don't rule out intermittent IDC connectors on the ribbon cables, though the 5V supply is fed in parallel from both cables so both would have to develop a problem for the 5V to dissappear, which would be uncommon.

The schematic of the ports board is here and the appropriate section of the main board is here. Sorry about the lack of quality in those scans, my original paper copies looked to have been photocopied and reduced several times over, so that's as good as you'll get.

When I check trace between pin7 and F160, it looks like short circuit. Also, when I check pin7 at the moment of power up I have about 1.6V, after that 1V, and after few seconds 0V.
Thank you for help.

[Castellen]

Originally Posted by Bokasa

When I check trace between pin7 and F160, it looks like short circuit. Also, when I check pin7 at the moment of power up I have about 1.6V, after that 1V, and after few seconds 0V.

You mentioned earlier that you had 5V at F160. So if you have 5V at F160 and there is nothing at pin 7, then there is obviously no connection between the two.

So you need to check again; is there 5V on both sides of F160 while there is not 5V at pin 7?

If the supply looks OK at F160, then follow the tracks through to the ports board. It probably goes through a ferrite bead or low value resistor on the way, so this would be the first area of suspicion.

[Bokasa]

Originally Posted by Castellen

You mentioned earlier that you had 5V at F160. So if you have 5V at F160 and there is nothing at pin 7, then there is obviously no connection between the two.

So you need to check again; is there 5V on both sides of F160 while there is not 5V at pin 7?

If the supply looks OK at F160, then follow the tracks through to the ports board. It probably goes through a ferrite bead or low value resistor on the way, so this would be the first area of suspicion.

Definitely I have 5V at F160 and ferrite FB556 at both sides, but there's no connection between pin 7 and fb556. Stripe cables and I/O port module are OK. I can't see resistors between FB556 and PIN 7 (pin4 at 40 pins motherboard connector). Any suggestion?
Thank you very much.