Hello Gerry.
The MAX232 IC is infamous for this kind of problem. They were used in some
of the early Packet Radio TNC designs, and every one that was soldered in, I
pulled out and installed a socket to ease future replacement. The bottom
line is that typically with Tx & Rx data, along with any CTS/RTS
hand-shaking connected (with LONG wires to this chip), you have the perfect
setup for any kind of lightening EMP to come in and wreak havoc. Of course
these TNC's were installed at remote commercial tower sites, so in the end,
I purchased RS-232 surge protection devices and put one at both "ends" of
the RS-232 cable, because as another writer mentioned, it also typically
came in and took out the computers UART chip as well. Back then 16450 and
16550 devices.
Just as a note, any RS-232 kind of ham will tell you that having an RS-232
monitor is close to essential in troubleshooting. These things are
available all over the place for $10 or less. You want to look at the your
Transmit and Receive data lines and check their status, as well as any odd
hand-shaking indications that might be present.
But for what it is worth, I'd start with the MAX232 itself, and after
carefully unsoldering it, install a socket. :-)
Mark
Wa3jpy
-----Original Message-----
From: Gerry Hull <gerry@w1ve.com>
Sent: Monday, July 2, 2018 7:49 AM
To: amps@contesting.com
Subject: [Amps] Alpha 87a No RS-232
Hello All,
We have two Alpha 87as at K2LE. They have been rock solid amps for
decades.
However, we operate remotely, and rely upon RS-232 using the great DF3CB
software.
We have the same failure mode in both amps. The TX side of the serial
port has failed. We can command the amp on,
But that is it. We have verified multiple times and multiple ways that
the cable and ports are working perfectly (short TX/RX Pins on the amp-side
connector and ensure echo on a terminal program).
I see very little about this subject in the archives. Has anyone else
experienced this?
Does anybody know if the Max232 chip is soldered? This is what I suspect,
since the amplifier is fully functional otherwise.
Is there some master reset we can try with a combo of front panel buttons?
Your collective wisdom appreciated.
73, Gerry W1VE
For Andy, K2LE and the team
--
Gerry Hull, W1VE Hancock, NH USA
Member: ARRL, YCCC, YCCCN, CW Ops
gerry@w1ve.com ph: 1-617-CW-SPARK (find me)
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