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Serial port voltage problems

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First post, by oldgames79

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Hi,

I have a voltage problems on my port COM1
My motherboard is a FIC 486 VIP PIO2 and my mouse doesn't work because I have +12v on all pin except on pin 4,5 and 7. There is no -12v. I have tested the PSU and there is -12v.

I have tested a serial port on an other motherboard where my mouse work and there are -12v on pin 2 and 3 and nothing else on the others pin.

Someone already had this problem.

There is a problems with the controller or the controller is defect?

PS: I have also tested the port COM2 and the problem is the same.

Reply 1 of 4, by SSTV2

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I had this exact problem with one of the 486 MBs. If you don't see -12V on the ISA slots, then you have the exact same problem as I did - corroded AT PSU header pins or corroded AT PSU connector pins.

Reply 2 of 4, by oldgames79

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It's a onboard controller not an isa card with the controller.

Reply 3 of 4, by higorfranco

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oldgames79 wrote on 2019-08-24, 08:20:

It's a onboard controller not an isa card with the controller.

Having the same here... any updates? I already tested with a PCI Controller and even the serial mouse doesn't work.

Reply 4 of 4, by oldgames79

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higorfranco wrote on 2023-02-24, 16:49:
oldgames79 wrote on 2019-08-24, 08:20:

It's a onboard controller not an isa card with the controller.

Having the same here... any updates? I already tested with a PCI Controller and even the serial mouse doesn't work.

Yes, I have change my serial connector. The pinout configuration was not the right one.

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