you can use a usb to rs232 ?converter (install it¡¯s driver) and like terra term or to communicate with the Gemini and see if its working?? It usually loses one line the Rx or Tx
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Send basic commands ASCI, HEX or Echo commands...or even listen to port data in hex or serial
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But the IC is easily available but i do ask what is pin 8 looking "black"??? Is it a photo effect.? The PCB does appears to have some mottled or water moisture marks.? Definitely needs a good clean up....and clean corrosion from small traces, by scrubbing off PCB resist...coat with solder and coating with UV dry PCB resist.
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Do check the rest of the PCB
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There are many vertical 4P4C jacks but this one will do.? TE (previously AMP) mrn 5520257-2, flanged 4P4C plastic thru hole socket RJ22, .? Digikey
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You can see plenty that will fit. . Just unshielded, Rj22, 4P4C vertical with or without panel flanges.?? You can see the ones that fit, l.?
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Lastly RS232 also is CPU related and yes I have seen these go bad.?? They go from U6 pins 11/9? to pins 71/72 of CPU.?? Pin 9 (R1 out) to pin 71.? Pin 11 (T1 in) from pin 72 CPU.?? U6 pin 8 (R1in) comes from serial socket pin 3.?? U6 pin 13 (T1 out) goes to serial socket pin 4.
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Test the caps by using a multimeter across them.? then reversing the leads...you get a very short "tick sound"
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Use plenty of flux...I guess you are ok at SMD ICs R&R....as these IC pads lift easily.? U6 is an MB3221 or ICL3221 in SSOP16 package for this version, make sure its SSOP16 or SSOPW. ??? Send some other PCB pics and underneath...so i can check the PCB condition.? If you want
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cheers
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Get back on how you go
--
Brendan
