Mesa 7i95 ssr bug / damage?

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Bocho
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05 Jun 2021 17:33 - 05 Jun 2021 20:11 #211236 by Bocho

Mesa 7i95 ssr bug / damage? was created by Bocho

Hello,

Please can someone explain strange behavior of ssr outputs?
Asserting ssr active signal on any 1-3 channel simultaneously turns on channels 3 4 and 5
Hal scope shows correct values (only selected channel is on) however ssr LEDs on mesa board for channels 3 4 5 become active.

26  bit   IN          FALSE  hm2_7i95.0.ssr.00.out-00
26  bit   IN          FALSE  hm2_7i95.0.ssr.00.out-01 <== tool-open-out
26  bit   IN          FALSE  hm2_7i95.0.ssr.00.out-02
26  bit   IN          FALSE  hm2_7i95.0.ssr.00.out-03
26  bit   IN          FALSE  hm2_7i95.0.ssr.00.out-04
26  bit   IN          FALSE  hm2_7i95.0.ssr.00.out-05
26  u32   IN     0x000F4240  hm2_7i95.0.ssr.00.rate

Thanks

Last edit: 05 Jun 2021 20:11 by Bocho.

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PCW
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05 Jun 2021 18:14 - 05 Jun 2021 18:14 #211237 by PCW

Replied by PCW on topic Mesa 7i95 ssr bug / damage?

That indicates a damaged 74ACT04 chip on the 7I95, most likely from 5V overvoltage

Last edit: 05 Jun 2021 18:14 by PCW.

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Bocho
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05 Jun 2021 20:08 #211247 by Bocho

Replied by Bocho on topic Mesa 7i95 ssr bug / damage?

PCW wrote:
That indicates a damaged 74ACT04 chip on the 7I95, most likely from 5V overvoltage

Fears were confirmed by the oscilloscope - the IC is dead.
Outputs 3-5 work fine, enough for the current setup.
Ordered 74ACT04 for resoldering.
Thank you!

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