New project: An ACT Apricot F1 "barn find"

[rubber_jonnie]

This thread is shaping up to be as long as one of mine

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.

Yeah, that voltage seems a bit on the high side for sure. I was about to say it's got a thermal problem, then you said it worked after freezing.

With regards to the MC1488, what is the 12v side rated for? That's what, about 12% higher? Sounds like a bit much, maybe it's that what's causing the thermals to go wonky?

[stephen_usher]

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.

[rubber_jonnie]

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.

Yes, probably the case they are just dying of old age then. Looking at the datasheet, 13.5v is well within what the chip will take, so probably ok there.

[stephen_usher]

Humph! The PCBs are still stuck in China.

boing-boing.JPG (173.62 KiB) Viewed 2426 times

[stephen_usher]

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.

[rubber_jonnie]

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.

Makes sense if it's a bit high then, if nothing is too voltage sensitive.

[rubber_jonnie]

Humph! The PCBs are still stuck in China.
boing-boing.JPG

Wow, that really is pinging around!

[stephen_usher]

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.

[rubber_jonnie]

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.

They are going to be seasoned international travellers by the time they arrive, very frustrating!

[stephen_usher]

The PCBs have reappeared in Germany, not on hold pending a technical issue. I'm guessing that this is a Brexit related problem.

I wonder if the other package will get similarly stuck.