A3000 RTC issues

brett71 · 01 February 2012, 17:51

Greetings,

Some time ago I picked up an A3000D from eBay and have done some upgrades/refurbs to it. One of the changes I had made was replacing the NiCad RTC battery with a more modern NiMH battery in the same form factor by a guy who used to be an authorized Commodore service tech back in the day, so I'm relatively confident the work was done right. However, both before and after the battery change, the clock behaved erratically.

The clock would of course keep perfect time while the machine was powered on. If I turned the machine off for an hour or two and powered it back up again, the clock would still have the correct time. However, if I left the machine off for a day or two, when I turned the machine back on, the clock would be several hours off. I attempted to find the amount of time that had to pass for the clock to start malfunctioning, but was never able to find that sweet spot.

I'm unsure where the fault is. Could the battery not be charging correctly? I've left the computer on for a week straight once to try to give the battery a nice charge-up, but then the clock would start misbehaving almost right away. Could there be a fault in the recharging circuit? Could the RTC chip be bad? Anyone have any other ideas? What else can I do to troubleshoot? I don't own a multimeter or even know how to use one to check to see if the battery is even getting any juice.

Thanks!

Jope · 01 February 2012, 19:18

There's not much we can say if you don't have a multimeter, but you sort of narrowed it down. Either the clock chip is shot or it isn't getting enough volts.

mfilos · 01 February 2012, 19:47

I had the same issues with an coin battery which was replaced on my A4000 mobo.
Turned out to be a discharged battery cause when I measured it, it was 2.4V while a new one was 3.2V.
Once I changed it I never experienced a time change again.

Imho, replace the battery with a new one and you'll be set.

mech · 01 February 2012, 19:57

Quote:

Originally Posted by mfilos

I had the same issues with an coin battery which was replaced on my A4000 mobo.
Turned out to be a discharged battery cause when I measured it, it was 2.4V while a new one was 3.2V.
Once I changed it I never experienced a time change again.

Imho, replace the battery with a new one and you'll be set.

There is a better solution in coin batteries than the CR2032 hack out there now. a 3.6V lithium coin cell called the LIR2032. Because of the higher voltage the amiga clock will be happier longer because the voltage will not drop too low as soon.Do not let the motherboard charge the LIR2032! you must still use a diode.
There are separate wall chargers to re-charge the LIR2032 it if it ever goes low.

Mech

mfilos · 01 February 2012, 20:07

Nice I didn't know that Mech mate.
Is it a compatible coin drop-off? Meaning is the size the same with the CR socket so it would be just a matter of replacing the CR one with the LIR one?

mech · 01 February 2012, 21:33

Quote:

Originally Posted by mfilos

Nice I didn't know that Mech mate.
Is it a compatible coin drop-off? Meaning is the size the same with the CR socket so it would be just a matter of replacing the CR one with the LIR one?

Yep,the size is the same, will fit your old coin holder if it used a cr2032. Drop in replacement.

Mech

SpeedGeek · 02 February 2012, 01:13

The battery voltage is certainly something you should try verify and you don't need an expensive DMM for that... the el-cheapos will work just fine for this task. The other possible besides the RTC (and I would try reseating before replacing the chip) is to look for possible corrosion on traces caused by the original battery. Your tech may have installed the replacement battery correctly but may not have bothered to clean the PCB before doing so.

brett71 · 02 February 2012, 23:53

The amazing thing about the 3000D I picked up was that the original NiCad battery was actually in fairly good physical shape (very little to no acid leakage) and I didn't see any corrosion on the topside of the mainboard.

Another 3000D I had prior to this one and I resold also showed the same symptoms, but that battery was in visibly worse shape and showed signs of corrosion on the board.

I'll try to pick up a multimeter from Radio Shack and see if I can pick up any voltage in the battery. Is there a way that I can also check to see if the clock chip is getting juice like it should?

Jope · 03 February 2012, 07:48

Yes, select 20VDC on the multimeter, the black probe goes on the minus terminal of the battery, and the red probe goes to pin 18 on the RTC chip U190.

How to count pins in chips:
http://en.wikipedia.org/wiki/Dual_in...lead_numbering

reinauer · 25 June 2021, 19:29

Quote:

Originally Posted by mech

There is a better solution in coin batteries than the CR2032 hack out there now. a 3.6V lithium coin cell called the LIR2032. Because of the higher voltage the amiga clock will be happier longer because the voltage will not drop too low as soon.Do not let the motherboard charge the LIR2032! you must still use a diode.
There are separate wall chargers to re-charge the LIR2032 it if it ever goes low.

Mech

What part of the battery specs and/or the Amiga charge circuit make the LiR2032 incompatible w.r.t in-system charging?

I have read in several places that this is the case, but nobody ever gave an explanation. Is this a matter of limiting the charge current?

gdonner · 25 June 2021, 21:34

A weird problem I've had with my A3000 RTC is that although the original Varta battery was removed (area cleaned) and replaced with a coin cell/diode (and the clock chip replaced too), when cold booted the date always reverts to February 28, 2018.

I've tried resetting the AMNESIA bit with SCSIPrefs and SetBatt, but to no avail. I can only assume it's a hardware issue that's cropped up since the repair a year or two ago. :-|

Warty · 26 June 2021, 05:48

err, doesn't that mean that it's not maintaining time at all when computer is off, but is instead reading from disk, the last known date of Feb 28, 2018? When I redid my A3000 battery, the 3.x install worked fine, and the 1.3 install would be stuck at a date a few days ago (I think when I first did it, but don't remember). It essentially wasn't reading the clock at all. (after I found the right piece of software for 1.3, it stopped being a problem).

pipper · 26 June 2021, 06:09

When the clock stores the last written time but does not advance it during machine power off, it is likely that the circuit providing the external 32khz is broken. Check very carefully around that. This happened to me and I found a broken trace around a via that previously had battery-green corrosion on it.

whaka · 27 June 2021, 17:45

Quote:

Originally Posted by reinauer

What part of the battery specs and/or the Amiga charge circuit make the LiR2032 incompatible w.r.t in-system charging?

I have read in several places that this is the case, but nobody ever gave an explanation. Is this a matter of limiting the charge current?

the way LiPo need to be charged is very different.
you need to control voltage and current in different state of the charge.
and this is done by a smart controller which sense what happen and physically stop charging when full, lithium don't like overcharging at all.

for charging NiCd/Mh you can do this with a very simple circuit, by only limiting the current very low, then this allow to let it in floating charging without any risks, and this is what amiga do.

01 February 2012, 17:51	#1
brett71 Registered User Join Date: May 2010 Location: Ames, IA, USA Posts: 521	A3000 RTC issues Greetings, Some time ago I picked up an A3000D from eBay and have done some upgrades/refurbs to it. One of the changes I had made was replacing the NiCad RTC battery with a more modern NiMH battery in the same form factor by a guy who used to be an authorized Commodore service tech back in the day, so I'm relatively confident the work was done right. However, both before and after the battery change, the clock behaved erratically. The clock would of course keep perfect time while the machine was powered on. If I turned the machine off for an hour or two and powered it back up again, the clock would still have the correct time. However, if I left the machine off for a day or two, when I turned the machine back on, the clock would be several hours off. I attempted to find the amount of time that had to pass for the clock to start malfunctioning, but was never able to find that sweet spot. I'm unsure where the fault is. Could the battery not be charging correctly? I've left the computer on for a week straight once to try to give the battery a nice charge-up, but then the clock would start misbehaving almost right away. Could there be a fault in the recharging circuit? Could the RTC chip be bad? Anyone have any other ideas? What else can I do to troubleshoot? I don't own a multimeter or even know how to use one to check to see if the battery is even getting any juice. Thanks!

02 February 2012, 01:13	#7
SpeedGeek Moderator Join Date: Dec 2010 Location: Wisconsin USA Age: 60 Posts: 846	The battery voltage is certainly something you should try verify and you don't need an expensive DMM for that... the el-cheapos will work just fine for this task. The other possible besides the RTC (and I would try reseating before replacing the chip) is to look for possible corrosion on traces caused by the original battery. Your tech may have installed the replacement battery correctly but may not have bothered to clean the PCB before doing so. Last edited by SpeedGeek; 03 February 2012 at 23:17.

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01 February 2012, 19:18	#2
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,912	There's not much we can say if you don't have a multimeter, but you sort of narrowed it down. Either the clock chip is shot or it isn't getting enough volts.

01 February 2012, 19:47	#3
mfilos Paranoid Amigoid Join Date: Mar 2008 Location: Athens/Greece Age: 45 Posts: 1,978	I had the same issues with an coin battery which was replaced on my A4000 mobo. Turned out to be a discharged battery cause when I measured it, it was 2.4V while a new one was 3.2V. Once I changed it I never experienced a time change again. Imho, replace the battery with a new one and you'll be set.

01 February 2012, 20:07	#5
mfilos Paranoid Amigoid Join Date: Mar 2008 Location: Athens/Greece Age: 45 Posts: 1,978	Nice I didn't know that Mech mate. Is it a compatible coin drop-off? Meaning is the size the same with the CR socket so it would be just a matter of replacing the CR one with the LIR one?

02 February 2012, 23:53	#8
brett71 Registered User Join Date: May 2010 Location: Ames, IA, USA Posts: 521	The amazing thing about the 3000D I picked up was that the original NiCad battery was actually in fairly good physical shape (very little to no acid leakage) and I didn't see any corrosion on the topside of the mainboard. Another 3000D I had prior to this one and I resold also showed the same symptoms, but that battery was in visibly worse shape and showed signs of corrosion on the board. I'll try to pick up a multimeter from Radio Shack and see if I can pick up any voltage in the battery. Is there a way that I can also check to see if the clock chip is getting juice like it should?

03 February 2012, 07:48	#9
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,912	Yes, select 20VDC on the multimeter, the black probe goes on the minus terminal of the battery, and the red probe goes to pin 18 on the RTC chip U190. How to count pins in chips: http://en.wikipedia.org/wiki/Dual_in...lead_numbering

25 June 2021, 21:34	#11
gdonner Ancient Amiga User Join Date: Mar 2018 Location: Elkhart, IN USA Posts: 208	A weird problem I've had with my A3000 RTC is that although the original Varta battery was removed (area cleaned) and replaced with a coin cell/diode (and the clock chip replaced too), when cold booted the date always reverts to February 28, 2018. I've tried resetting the AMNESIA bit with SCSIPrefs and SetBatt, but to no avail. I can only assume it's a hardware issue that's cropped up since the repair a year or two ago. :-\|

26 June 2021, 05:48	#12
Warty Registered User Join Date: Aug 2018 Location: Minneapolis, USA Posts: 301	err, doesn't that mean that it's not maintaining time at all when computer is off, but is instead reading from disk, the last known date of Feb 28, 2018? When I redid my A3000 battery, the 3.x install worked fine, and the 1.3 install would be stuck at a date a few days ago (I think when I first did it, but don't remember). It essentially wasn't reading the clock at all. (after I found the right piece of software for 1.3, it stopped being a problem).

26 June 2021, 06:09	#13
pipper Registered User Join Date: Jul 2017 Location: San Jose Posts: 676	When the clock stores the last written time but does not advance it during machine power off, it is likely that the circuit providing the external 32khz is broken. Check very carefully around that. This happened to me and I found a broken trace around a via that previously had battery-green corrosion on it.

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