Is my RTC chip bust on my ACA 1230/56?

[vroom6sri]

Shamefully I hadn't used my Amiga for a long time and when I kissed it up I noticed the time and date were out. I just thought it was due to a flat battery so replaced it but that doesn't seem to have fixed it. Then I noticed that some of the connectors seem to have broken off the real time clock chip but I don't know how as the trapdoor was closed.

Should they be missing some of the connectors normally?

[-Acid-]

My A4000 was recapped and coin battery slot soldered onto the board (there was no damage to it whatsoever) and it loses time every single time it's turned off. It is really annoying and makes me wonder does any RTC actually keep the correct time in any Amiga model? I've never seen one yet that does.

[Daedalus]

All 3 of my A1200s with various different expansions all keep the time perfectly. They've had occasional failures (usually batteries, but my B1260 had a failed diode also), but once they're repaired they go back to working perfectly. Are you sure the coin battery is ok, and that a diode was fitted to prevent the charging current from reaching the cell? Without the diode, the cell will be destroyed by the charging current and will effectively be flat within days.

[Daedalus]

As for the original post, it looks like those pins were deliberately removed - if they'd broken I'd expect to see damage around the area, probably on the adjacent pins, and the pins would likely still be gripped in the socket. To be sure though, I'd contact Jens and see what he says. Also, most accelerators map the RTC chip to where it should be and so it works automatically, but maybe the ACA is different and needs a command in the startup-sequence to load the clock? I'm not familiar with them so I can't be sure...

[vroom6sri]

Thanks for the suggestions. I will check the replacement battery again first.

[demolition]

The RTC runs fine in all my Amigas as long as the battery level is good. It might be off a few seconds after some time, but perfectly acceptable. Whenever the battery starts to run low, I see that the clock starts going slow when the Amiga is switched off.

[RedskullDC]

Hi Vroom, et al.

Originally Posted by vroom6sri

...Then I noticed that some of the connectors seem to have broken off the real time clock chip but I don't know how as the trapdoor was closed.

Should they be missing some of the connectors normally?

Those 2 pins on the RTC chip (16 & 17) were likely snipped off when the board was being assembled.

The RTC62421 is basically the same as the earlier 6242 chip, except that it has an integrated crystal.

On the 6242, pins 16 and 17 are where the crystal is connected.
The 62421 must have these pins left unconnected, see the datasheet at:
http://www.promelec.ru/pdf/rtc62421.pdf

This board is designed for a 6242 chip, as it has a 32kHz oscillator in the lower right corner (part marked 32C16).
Snipping the 2 pins means that the chip can safely be used in a circuit designed for a 6242 without altering the PC board.


Double check your battery, otherwise try a replacement 62421 chip.
Only $4.50US on Ebay: http://www.ebay.com/itm/272103803679

Cheers,
Red

[-Acid-]

Originally Posted by Daedalus

All 3 of my A1200s with various different expansions all keep the time perfectly. They've had occasional failures (usually batteries, but my B1260 had a failed diode also), but once they're repaired they go back to working perfectly. Are you sure the coin battery is ok, and that a diode was fitted to prevent the charging current from reaching the cell? Without the diode, the cell will be destroyed by the charging current and will effectively be flat within days.

Hikey recapped the board for me last year and put the battery in so i'm unsure if it was a new one or not or if the diode you mention is installed there. I just turned my A4000 on and it thinks it's the 12th of Dec 2015 00:06 right now. I'm sure i've put it right in the last week so I don't know what's going on. I will set it again and then switch it off for a few hours and see what happens.

[amigasith]

@vroom6sri Although I don't have an ACA 1230, the CR1220 battery holder on my ACA 1231 is really picky when it comes to placing the battery in correctly.

What I had to do was to put the battery in and turn it around a couple of times to make good contact. I also bent up the two metal springs at the bottom of the battery holder to generate more pressure for better contact.

Look at the underside of your ACA and find out where the voltage pins of the battery holder are. Then measure the voltage to make sure that the battery really has contact.

@-Acid- Like demolition said, also all of my Amigas hold time perfectly as long as the batteries are good. Doesn't matter whether it's the barrel type batteries or coin cell batteries, doesn't matter whether it's the OKI or RICOH clock ICs.

[vroom6sri]

Wow! Thanks very much for all the detailed info.