Stuck channels on a 16550A

  • Thread starter Harout S. Hedeshian
  • Start date
H

Harout S. Hedeshian

Guest
I have a 16550A with several stuck channels. One of them is always
stuck hi and two other stuck low. I checks the cables on another card
and they work fine. When I boot the 16500B into diagnostic mode, the
card passes all self diagnostics and it shows that all channels are
changing, but when rebooted in to normal mode, the hi channel always
shows hi even if I short it to ground. This leads me to believe that
the problem is somewhere before the sampling ICs. How likely is it that
one of the 1DX5-001 has gone bad? Does the self-diag test these? Is
there any part you would suggest I troubleshoot first? Does anyone else
have a 16550A with stuck channels that they are willing to sell for
parts? Or any known good 1DX5-001 [P]LCC parts?

Thanks,

Harout S. Hedeshian
harout@hedeshian.net
 
Harout S. Hedeshian wrote:
I have a 16550A with several stuck channels. One of them is always
stuck hi and two other stuck low. I checks the cables on another card
and they work fine. When I boot the 16500B into diagnostic mode, the
card passes all self diagnostics and it shows that all channels are
changing, but when rebooted in to normal mode, the hi channel always
shows hi even if I short it to ground. This leads me to believe that
the problem is somewhere before the sampling ICs. How likely is it that
one of the 1DX5-001 has gone bad? Does the self-diag test these? Is
there any part you would suggest I troubleshoot first? Does anyone else
have a 16550A with stuck channels that they are willing to sell for
parts? Or any known good 1DX5-001 [P]LCC parts?

UPDATE: I jumped the bad channel (always showing hi) to the input
Click to expand...
channel on another pod that one showed hi as well. If I check the
voltage on a normal channel with my voltmeter, I get 0 volts. But the
stuck channel shows 1.4 volts all the time. Jumpering that channel to
ground accomplishes nothing. It is bit #3 on pod 1, does anyone know
which chip to check?
 
Harout S. Hedeshian wrote:
Harout S. Hedeshian wrote:
I have a 16550A with several stuck channels. One of them is always
stuck hi and two other stuck low. I checks the cables on another card
and they work fine. When I boot the 16500B into diagnostic mode, the
card passes all self diagnostics and it shows that all channels are
changing, but when rebooted in to normal mode, the hi channel always
shows hi even if I short it to ground. This leads me to believe that
the problem is somewhere before the sampling ICs. How likely is it that
one of the 1DX5-001 has gone bad? Does the self-diag test these? Is
there any part you would suggest I troubleshoot first? Does anyone else
have a 16550A with stuck channels that they are willing to sell for
parts? Or any known good 1DX5-001 [P]LCC parts?

UPDATE: I jumped the bad channel (always showing hi) to the input
channel on another pod that one showed hi as well. If I check the
voltage on a normal channel with my voltmeter, I get 0 volts. But the
stuck channel shows 1.4 volts all the time. Jumpering that channel to
ground accomplishes nothing. It is bit #3 on pod 1, does anyone know
which chip to check?
Click to expand...
UPDATE: I traced the bad channel back to the corresponding 1DX5-001
chip. I swapped those two with known working ones from another pod.
Sure enough the bad channel showed up on the pod I switched it to. I
moved the chips around such that pods 1-4 are working but 5 and 6
currently have bad channels. SO... Does anyone have a 16550A that has
at least two good pods that they are willing to pawn off? OR does
anyone have 4 DX5-001 chips?
 
Hello
what Types of Electronics do U have I do Need Laptop computer
or Ipod with Portable dvd Okay? so what do U have out of the
Three.....?
Regard.

Troy....
Harout S. Hedeshian wrote:
I have a 16550A with several stuck channels. One of them is always
stuck hi and two other stuck low. I checks the cables on another card
and they work fine. When I boot the 16500B into diagnostic mode, the
card passes all self diagnostics and it shows that all channels are
changing, but when rebooted in to normal mode, the hi channel always
shows hi even if I short it to ground. This leads me to believe that
the problem is somewhere before the sampling ICs. How likely is it that
one of the 1DX5-001 has gone bad? Does the self-diag test these? Is
there any part you would suggest I troubleshoot first? Does anyone else
have a 16550A with stuck channels that they are willing to sell for
parts? Or any known good 1DX5-001 [P]LCC parts?

Thanks,

Harout S. Hedeshian
harout@hedeshian.net
Click to expand...
 
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