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From: bp@www.zefox.net
Newsgroups: sci.electronics.repair
Subject: Re: Waking up a serial port
Date: Mon, 17 Mar 2025 15:34:59 -0000 (UTC)
Organization: A noiseless patient Spider
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References: <vr4der$3ugtc$1@dont-email.me> <sfbgtjhvrufa9nal1lpreqa63nhat3dsdk@4ax.com>
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HW <none@no.no> wrote:
> On Sat, 15 Mar 2025 17:30:03 -0000 (UTC), bp@www.zefox.net wrote:
> 
>>Are there any customary tricks to making a diagnostic serial port
>>active?
> 
> I am not aware of any standards.
> 
> Some devices will respond to a few CR-LF, as in pressing the enter key
> a few times, but those are probably mostly intended to be accessible
> by the user.
> 
> A device like this may very well have the serial port disabled in
> firmware.

I did briefly try to connect a usb-serial adapter, hoping to see at
least garbled boot messages during power up by varying baud settings.
Nothing at all appeared on the terminal screen. That's when I tried
the 'scope and found nothing. 

There are some board photos at
http://www.zefox.net/~bp/ampinvt/2nd_inverter/board_photos/
Please note it's http:..., not https. You'll have to pacify
your browser if it doesn't like unencrypted connections.

Thanks for replying,

bob prohaska