Amiga 4000 real time clock nightmare

[arttu80]

Hi!

Here I try again to ask for some help...Any ideas are welcome!

Here is this case; when I turn on computer, system does not see the clock (just checking by running SysInfo program). But when I run "SetClock Save" command, this apparently turns on RTC. Is it possibble to narrow down as to what may cause this?

Ofcourse battery has eaten some of motherboard traces, which I tried to repair. Using multimeter continuity check and resistance checks, following this fine guide ---
 http://amiga.serveftp.net/RTCrepair.html
Also used Amiga PCB Explorer --- http://www.amigapcb.org/

All measured within this guide spec.
Replaced RTC chip with new one (socketed this time), also installed new 74HCT174 (U177) chip.

Also running CR2032 battery with diode in place of R179 resistor. The voltage on pin 18 U178 about 3,0V when power is off. Still RTC isn't holding time when computer is turned off or reset is made.

Here is short video of my problem. Apologies for shakin camera and all.

https://www.youtube.com/watch?v=0XKsO42jcmk

[arttu80]

After a lot of frustrating evenings over this problem, after a lots of measurings and testings I finally found something interesting. I removed ide drive and booted machine from floppy. And guess what, RTC is working like new. It's holding time and all. But if I install hard drive (no matter is it real IDE or CF card with adapter) it become lost again on a bootup. Soo, is it possible that IDE circuit is messing somehow with RTC?

[F0LLETT]

Might sound stupid. Is there something in the startup sequence setting clock?
Try booting with no startup, then assign ENV RAM and loadwb, endcli. See if time is correct then.

After a lot of frustrating evenings over this problem, after a lots of measurings and testings I finally found something interesting. I removed ide drive and booted machine from floppy. And guess what, RTC is working like new. It's holding time and all. But if I install hard drive (no matter is it real IDE or CF card with adapter) it become lost again on a bootup. Soo, is it possible that IDE circuit is messing somehow with RTC?

[arttu80]

Thank you for suggestion,but no, that wouldn't help here.

I probed pins on U177 (74HCT174) chip with simple led test and I noticed that all Address line and Data line pins are switching rapidly but Q3 (pin 7) is stuck HI, but anyone here to tell is it supposed to or not? D3 (pin 6) is switching..