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Best way to test serial ports on an SE/30
Posted by: ironhalo on 2022-01-25 20:51:43
After several rounds of troubleshooting I have my external floppy and SCSI ports fully functional again. Now it’s time to focus on the serial ports.

What are the preferred ways of thoroughly testing these on an SE/30? Is it possible to cable them together and test them in a loopback configuration via some software utility? Or should I just dig out an old modem (and hope it still works) to send some AT commands to it via ZTerm? If the latter, would receiving AT replies from the modem prove the port is fully functional, or is more thorough testing of some kind required to come to that conclusion?

Thanks in advance!
Posted by: Nixontheknight on 2022-01-26 12:07:24
for the modem port, test it using a modem, and type some AT commands, if you get back nothing or garbage (and you're sure you're at the right baud rate), it's bad, but if you get OK, it's good. As for the printer port, test it using AppleTalk, which would probably be a moot point if you don't have another mac with a printer port.
Posted by: ironhalo on 2022-01-26 13:11:00
Yeah, don’t have another working Mac or printer here at the moment to test with, which is why I was hoping there might be a clever way to test one port with the other. Perhaps with a custom made serial cable and a diagnostic utility of some sort.
Posted by: sstaylor on 2022-01-26 13:28:39
The old Apple service test software used what they called a "serial loopback cable" which you would plug one end into each serial port, but I couldn't tell you how it was wired. Perhaps it was just a plain null-modem cable but i honestly don't know.
Posted by: ironhalo on 2022-01-26 14:21:00
The old Apple service test software used what they called a "serial loopback cable" which you would plug one end into each serial port, but I couldn't tell you how it was wired. Perhaps it was just a plain null-modem cable but i honestly don't know.
Yeah, that's exactly what I was imagining. Would have been silly for them not to have a procedure for that considering how easy it likely was to implement.

Is that Apple service test software for the SE/30 hardware something that is easy to find? I don't see anything like that on MacintoshRepository (searching "service" under the 68k category).

Is this it? https://www.macintoshrepository.org/104-apple-personal-diagnostics
Posted by: sstaylor on 2022-01-26 14:43:49
I've been scratching my head trying to remember what Apple called the official testing software for repair providers. ServiceSource? AppleTest? It's been too long and my brain is in a cloud at the moment. I'll keep thinking and if I remember I'll let you know.
Posted by: ironhalo on 2022-01-26 15:23:14
Cool, thank you. I'm intimately familiar with AST and ASD, as I managed an authorized Apple repair shop starting around 2005. However I'm completely in the dark on whatever software existed for service techs on the 68k platforms.
Posted by: craig1410 on 2022-02-01 14:18:28
You might be thinking about MacTest SE/30 although I've not managed to get it working since it requires a SCSI loopback device as well as a serial loopback cable. What I've been using is Snooper which can test individual ports (modem or printer) by looping pins 1 to 2 and 3 to 5 inside the port. I just did this with the legs of an axial resistor chopped off. Pins 1 and 2 are the ones at the bottom and pins 3, 4 and 5 are the next layer up. No need to bridge 6, 7 or 8.

HTH - links below.

MacTest SE/30 - Macintosh Garden

Hardware diagnostics provided to Apple dealers and other service providers (usually large companies, schools or universities) for the Macintosh SE/30 Download #1: contains DC 4.2 image of MacTest SE/30 Version F1-1.0. (French) If anyone has a physical SE/30 and can provide a screenshot, please...
macintoshgarden.org macintoshgarden.org

Snooper - Macintosh Garden

Snooper 2.0 detects hardware problems and sources of intermittent failures. It performs over 200 major component tests, prints the results, and logs errors. It also does benchmark testing and reports on system configurations to allow technicians to find and fix problems quickly.
macintoshgarden.org macintoshgarden.org
Posted by: ironhalo on 2022-02-02 11:49:13
Excellent info, thanks Craig. I will give Snooper a shot at testing the serial ports.
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