Amiga RAM Expansion A501 RTC Battery Replacement (Read desription first!)

[@sophiestabilitronics]

Congratulations, Sir! Very helpful here since it is hard to find supercapacitors here. CR2032 is more abundant. Very useful mod for everything! Subscribed to your channel! Greetings from Philippines!

[@jmicari]

In the schematic you drew up the diode was in between the 5v supply and the positive terminal of the battery. But in the video you placed the diode between the positive and negative terminal. Am I missing something?

[@Dukefazon]

You set the clock to 8:22, turned off and back on 10 minutes later so 8:23 ain't right. What happens if you have an expension card but no battery is on board?

[@robbiew73]

@Jan Beta - would this battery and diode hack work for replacing the battery on the A500Plus motherboard?

[@JanBeta]

Yes, the clock circuit is pretty much the same. There’s pre-made drop in PCBs for that purpose that fit both, too.

[@robbiew73]

Interesting.. that's good to know.. I just took out my battery yesterday to save the machine from certain death.. there was a small amount of corrosion - some blackened copper tracks, but nothing too extensive..

[@FernandoelChachi]

Many thanks, man. I'm just following your steps. Much appreciated ;)

[@sergiopellegrini1058]

silly question: why didn't you put a rechargeble cr2032?

[@joestradamus75]

do you actually need the battery in order for the RAM Expansion to work? Doesn't it work without it, aside from keeping the clock working?

[@JanBeta]

Yup, the battery is only needed for the clock part to work. The RAM works fine without it.

[@SpeccyMan]

How about replacing it with a LIR2032 3.6v rechargeable battery? Same form factor as a CR2032.

[@JanBeta]

Nick B Yes, that should work without any problems (and diodes).

[@boke75]

Anybody noticed that his new protection diode (1n4148) was installed improperly ? Instead of properly putting the diode in series with the "+" battery terminal, he placed the diode in parallel with the cr2032 battery terminal (and thus the cr2032 battery). Also, wouldn't this discharge the battery down from 3v to 0.7v through the "protection" diode ?

[@JanBeta]

The battery is actually soldered in the wrong way, not the diode (read the video description). The battery is only going to be drained by the forward voltage powering the clock ic if installed properly.

[@SparksNZeros]

was just re-watching this and thinking that if a vertical mount battery holder was fitted (like the one found in some models of dreamcast) would that be a better fit?

[@JanBeta]

Mh, might be worth a try. I think some of the flat types fit better than the one I used, too. I actually plan on making another (better) video about refurbishing the RAM expansions some time. Maybe even using rechargeable batteries.

[@Zsolt_Peter_Kodner]

Is this a Rev. 5 model?

[@wimwiddershins]

Great videos, Jan.

[@JanBeta]

Thank you! :)

[@TheHighlander71]

Loved it! Question though. Do you have to do any calculation to determine whether the diode is fit for the voltage or the current it's supposed to limit? I would imagine that a diode can get warm as well? Just curious...

[@JanBeta]

+The Highlander Thanks! I think the standard 1N4148 is rated for 75V or something like that, so I didn't do any extra calculations on that. I guess these will get really warm if you push them to their limit but this one is far from what it can take.

[@TheHighlander71]

Ah ok. 75V is way beyond what it needs to here. Check, thanks.

[@andreamanno4726]

Hi Jan, once again I have to ask you for help, I should mount a 3.6v lir 2032 rechargeable battery instead of the varta demon, I wanted to know just for confirmation since the battery is rechargeable, I just have to solder the battery holder without having to put put the resistor? thank you Ps: this could be useful to everyone www.amigapcb.org/

[@JanBeta]

I would not recommend using a 2032 rechargeable lithium cell. It will probably work but lithiums cells usually work quite differently than the original batteries. The circuitry does not have any charging control so the lithium cells will be overcharged in theory which will in the worst case make it burst in flames. You would have to add at least a charging control chip for lithium cells to be safe. :/

[@andreamanno4726]

@@JanBeta Does the problem of the 2032 lir also apply to the 3v refillable ml2032? or is the only rechargeable that can be mounted only the varta demon?

[@JanBeta]

The charging circuit is only safely useable with Varta style barrel batteries. Lithium cells always require charging control circuitry to prevent overcharging. The method with a non-rechargeable battery and the diode usually works for years without replacing though.

[@andreamanno4726]

​@@JanBeta so the only type of battery that I can put is the cr2032 with this device? amigakit.amiga.store/product_info.php?products_id=1093

[@SkuldChan42]

13th of October 1978 must be the Amiga DOS Epoch. Also I just got done with a similar clock battery mod for an Amiga 4000 I'm restoring.

[@JanBeta]

+SkuldChan42 I think the Amiga clock counts the days from January 1st, 1978. Don't know why that's the starting point, though. Hope your restoration is successful. A4000 is an amazing machine!

[@SkuldChan42]

It is - I fixed all the really bad broken parts of it today. I did film the highlights so hopefully there will be a video soonish :).

[@JanBeta]

+SkuldChan42 Nice! Looking forward to watching that.

[@PeteAU9]

Maybe the OS does that, but the clock chip stores day, month, year, hh, mm, ss etc in separate counters. P.S. Use a schotky diode instead, it will make the battery last longer. P.P.S I made a whole A501/CR2032 replacement board if anyone's interested.

[@JanBeta]

+PeteAU9 Ah, good to know about the counters. I heard about Schottky diodes being better suited for this job. Have yet to try one though. Thanks for sharing the info. Do you have the replacement boards for sale somewhere?

[@fum33z]

did you actually get the polarity right? :D

[@JanBeta]

+Andrei Esanu I was so tired that I could actually have gotten it wrong. Nothing exploded, so I guess it's about right?! ;)

[@JanBeta]

Sadly, you're right. I soldered in the battery holder the wrong way round. D'oh! Have it fixed now. Sorry, folks. :/

[@fum33z]

no worries man! keep up the great videos.

[@JanBeta]

Andrei Esanu Thanks. :)

[@MatthJenks]

So he installed the battery backwards and it still worked? I'm so confused. How could that possibly work?

[@hollgo626]

I got myself a chargeable CR 2032 för thus purpose....

[@peddersoldchap]

11:39 *eight hundred and eighty seven thousand The germanyness is too strong with this one! :)