exxos's Atari, Amiga & retro forum

stephen_usher wrote: 29 Jun 2021 10:38

rubber_jonnie wrote: 29 Jun 2021 09:25 This thread is shaping up to be as long as one of mine :)

:dizzy:

Hehe. Yeah, well, maybe the floppy cable connector and WD2797 daughter board will arrive together at this point, after the cable connector has finished its World tour, or they'll forever be bouncing between Europe and Chna until the end of time. :-)

As for the F1, the serial port was working again this morning for a while and then stopped.

It can only be the RS232 line driver chips, though I'm not sure which one as I got the interface to work again by freezing them both. I should have done one at a time.

Though the +12V rail is rather high at 13.5V!

P.S. It's the output driver chip '1A' I think. It's an MC1488.

stephen_usher wrote: 29 Jun 2021 11:45 I believe that it's merely controlling the voltages rather than using them as such. Given that it stops even if there's nothing connected to the serial port (and hence no current flow) it's probably not the voltage but rather the silicon aging and on the way out. The chip in question is in a part of the board which got a lot of weathering so there's a possibility of internal corrosion on the die.

Also, RS232 is supposed to support voltages up to 24V remember.

stephen_usher wrote: 29 Jun 2021 15:15 I just checked the +12V rail when the original floppy drive is connected and it goes down to 12.9V, which is still high but it just shows that the PSU +12V rail isn't exactly regulated very well.

On the system it's used only to provide power to the IR receiver sensors, the floppy drive and the output on the RS232, none of which are highly sensitive to the voltage, which is why they didn't bother with the proper regulation.

stephen_usher wrote: 29 Jun 2021 14:44 Humph! The PCBs are still stuck in China.
boing-boing.JPG

stephen_usher wrote: 01 Jul 2021 09:47 Well, the cable adapter boards are still touring Asia, having left Shenzhen about two days ago and have disappeared into the ether. DHL are no-longer quoting an ETA.

The second boards have just entered the DHhell system so who knows where they will visit.

I'm not sure I'll order from PCBWay for a little while. They're in the middle of a factory move and are just bringing the new plant on-line so their processing is likely to have some teething problems. At least their production time may get back down to 24 hours soon. I think they're been having to ship stuff between factories at the moment.