New member. Old Amiga 500 resurrection story

[Rissy]

More success today. Managed to dedicate my morning to the Ebay A501 Rev C board. Attached is a before and after comparison. I decided to clean up the baord before even testing it on my Amiga. I just wasn't happy with the condition of it as it was, and didn't want to risk damaging the computer as a result of being "slap-dash". So i spent around 4+ hrs working on it to clean it up. It does't look too bonny, but I've now tested in my Amiga and it's working. Woo-hoo! I'm back up to 1MB of RAM, even if it's not my original card. Very pleased. I'll still make an effort to repair my original.

So i have a question. I bought a replacement battery for my original Rev 5 A501 board, but because that's not working, I've got it sat to the side right now. Looking at the schematics for the Rev 6C board, it specifies 4.5V 100mah for the battery connected. My battery, and in fact the battery that goes on the Rev 5 board is a 3.6V 80mah. I can't seem to find a 4.5V 100mah battery with the three leg configuration anywhere. So will it be ok to use the 3.6V 80mah battery on the Rev 6C board considering it's a lower voltage and less mah?

This is a link to the exact battery I have bought: https://www.ebay.co.uk/itm/VARTA-MEM...H/260890458144

My other question is; should I be trying to tin the exposed copper on the board with my soldering iron after cleaning it up, or should i just give it a lick of some nail polish or something?

[amigakit.com]

You can get special PCB paint that will cover over exposed tracks. I can ask our in-house technician what brand he recommends.



If you find the refurbishment too time consuming we have brand new UK stock of A500 memory expansions at very low price here: http://amigakit.amiga.store/product_...7&currency=GBP

[solarmon]

Originally Posted by Rissy

If you put a search into eBay for “4164 41256”, there’s two hits that come up for the UK. I spoke to both chaps, each saying their little device would work on my chips, but the one with the tester containing two test slots was a bit more definite with his discussion with me, so his gave me more confidence. That’s the one I went for.

Ah, yes, those ones. They certainly look useful. Let us know how you get on with it.

[solarmon]

Originally Posted by Rissy

This is a link to the exact battery I have bought: https://www.ebay.co.uk/itm/VARTA-MEM...H/260890458144

Typically, a non-rechargeable coin cell battery is used as the replacement (with appropriate diode to stop the charge current), as getting a replacement Varta Ni-Mh battery is just asking for trouble again!

[Rissy]

Originally Posted by solarmon

Typically, a non-rechargeable coin cell battery is used as the replacement (with appropriate diode to stop the charge current), as getting a replacement Varta Ni-Mh battery is just asking for trouble again!

Yes, i'm aware of this, however, I've reasoned that the Amiga wont be shoved in a box and stored in the loft for 20+ yrs again, so i thought i'd get it back to being battery backed and recharging again. The battery should be good for at least 10yrs, maybe 15yrs.

Do you think it'll be ok? Power wise.

I made up a home made serial null modem cable today. This one including the shorting links my ebay one was missing. I'm getting the same behaviour with it as the other one.

I need to type: "newshell AUX:" to allow me to issue commands from the laptop keyboard. Typing "newshell SER:" doesn't allow typing. Is this perhaps down to my dongle?

Now that i have my Ebay 512k expansion card in play, interestingly enough, although the memory count at the top of the WB1.3 banner has increased, it still displays the warning during loading that there is no battery backed realtime clock detected. Why would this be? Fauty RTC chip, or do i need to get a battery on there (i don't see why if it's receiving power from the motherboard!?) before it'll detect it?
toADFish seemingly doesn't do a check for the RTC, as it doen't issue the same warning that my WB1.3 disc does. Is this true/normal?

[Rissy]

Originally Posted by solarmon

Ah, yes, those ones. They certainly look useful. Let us know how you get on with it.

I sure will. I'll post a video give it a demo even.

[512k]

@rissy

If you have an expansion with a rtc on it check this thread

https://eab.abime.net/showthread.php?t=19250

[Rissy]

Originally Posted by 512k

@rissy

If you have an expansion with a rtc on it check this thread

https://eab.abime.net/showthread.php?t=19250

Oh right, so if the Amiga thinks the time is still its default time, then irrespective of having a RTC, if it's not battery backed to be other than something default, then it's detected as being not present. Correct?

[Rissy]

Right, i've confirmed this. I put a copy of AmigaTestKitV1.16 ADF on to a floppy disc and booted from that. I not only managed to test my memory, i also got to test the RTC, and set it to today. Resetting the Amiga again with WB1.3 disc back in the drive allowed it to boot up and this time it told me the correct date/time details that i had set using AmigaTestKitV1.16 (because it hadn't been powered down, only reset). So i guess now as long as I apply a battery to the expansion card, all should be good and the Amiga stays in the 21st century (at least with that card in).

Interesting program AmigaTestKitV1.16. I even did a test on my keyboard keys. All seem to be working fine, except funnily enough, the left "Alt" key, which wouldn't light up green, and i couldn't use the command "CTRL-L.Alt" to take me back to the main menu either. So unless someone can tell me this is a bug with that piece of software, it turns out i'm missing my Left Alt key function! I would never have known otherwise!

[solarmon]

@Rissy,

Regarding the RTC:

* The RTC chip can fail - it is not uncommon to have to replace it.
* The RTC chip usually requires between 2V and 7V - anything outside of this it will not work - so check what voltage the RTC chip is getting.
* Removing the battery can mess with the voltage getting to the RTC chip - sometimes it does not pull it down enough to be within thre 2V-7V range (from the 12V supply) -so again, check the voltage getting to the RTC chip.

Regarding the key - if it is just one key not working, it is sometimes the plunger of the key. Swap it with another plunger and see if the problem follows or not. Obviously this requires taking the keyboard apart, which is not a quick thing. But it could easilu be the pad or trace going to the key.

[Jope]

If the rubber on the plunger is the problem, then they can often be rejuvenated by wiping the rubber on a piece of ordinary white paper.. 5-10 wipes, clean off any dust and very often the key starts typing again.

[Rissy]

Thanks chaps, as always.

I was thinking today. Someone once said i could drag Amiga Explorer on to the RAM DISK on the desktop of WB1.3 to run it, and take the necessity away from the disc drive. I've tried this now, and that indeed works. But it got me thinking. How much space does this RAM DISK have? I know it's volatile memory, so it resets back to I presume just Kick Start being on there, but how much can you actually put on there whilst the machine is powered?

[Rissy]

In other news. I've ordered myself a key puller from Ebay. I'll admit i'm quite nervous about trying to take the keyboard apart. It looks clean as a whistle, and every key works except the left Alt key. When on earth does anyone ever use the Left Alt key anyway!?

I've looked at the underside of my keyboard. Guess what. It's a Samsung. Eeek.

[robinsonb5]

Originally Posted by Rissy

But it got me thinking. How much space does this RAM DISK have? I know it's volatile memory, so it resets back to I presume just Kick Start being on there, but how much can you actually put on there whilst the machine is powered?

It just allocates enough system memory to hold whatever you put in there, so its capacity depends on how much memory you have installed in the machine. It'll hold a lot more now you have a trapdoor expansion working.


(If you fill it completely, you'll have no memory left to actually run anything though, so it's a bit of a balancing act!)

[Rissy]

Originally Posted by robinsonb5

It just allocates enough system memory to hold whatever you put in there, so its capacity depends on how much memory you have installed in the machine. It'll hold a lot more now you have a trapdoor expansion working.


(If you fill it completely, you'll have no memory left to actually run anything though, so it's a bit of a balancing act!)

Ah right! That makes sense. Thanks for explaining it to me!

[Jope]

Originally Posted by Rissy

In other news. I've ordered myself a key puller from Ebay. I'll admit i'm quite nervous about trying to take the keyboard apart. It looks clean as a whistle, and every key works except the left Alt key. When on earth does anyone ever use the Left Alt key anyway!?

I've looked at the underside of my keyboard. Guess what. It's a Samsung. Eeek.

Left alt has a line of its own, so there may be a break in one of the membranes.

Samsung is quite fiddly to take apart and put back together, as it has the return springs internally instead of under the keycaps. I wouldn't remove any keycaps unless you absolutely must, especially if the keyboard is very clean on top.

[Rissy]

Originally Posted by Jope

Left alt has a line of its own, so there may be a break in one of the membranes.

Samsung is quite fiddly to take apart and put back together, as it has the return springs internally instead of under the keycaps. I wouldn't remove any keycaps unless you absolutely must, especially if the keyboard is very clean on top.

From all the YouTube videos i've been watching lately regarding Amiga repairs, I became aware of the potential keyboard origins, although i'm not fully aware of the actual differences. Can you still use a key puller on the Samsung keys? (I bought one from ebay last night)
Typical i should end up with the most problematic version (by the sounds of it).

I believe they are the rarer of the two variants too? After reading your comment above, I had a look at ebay again, and someone is actually selling a complete A500 Samsung keyboard in good untested condition. So i bought it. If it fully works, great. If not, then at least i have spares for my original if I need them, and want to attempt to repair my L.Alt key.

[Jope]

Yes, you can use a key puller, it won't hurt anything, but won't really be useful in getting your faulty Alt key to work.

Any repairs will happen to the membranes inside the keyboard, things will stay together better when disassembling it if you do not pull any keycaps.

Yeah, it is probably the rarest style of Amiga keyboard. Also one of the worst typing feel. :-)

[Rissy]

Originally Posted by Jope

Yes, you can use a key puller, it won't hurt anything, but won't really be useful in getting your faulty Alt key to work.

Any repairs will happen to the membranes inside the keyboard, things will stay together better when disassembling it if you do not pull any keycaps.

Yeah, it is probably the rarest style of Amiga keyboard. Also one of the worst typing feel. :-)

So are you saying I should leave the keys on, but just unscrew the metal back plate, and pull that from the rest of the assembly? Will that work? I thought you had to pull the keys off to be able to remove the backplate....?

[Jope]

It will make things much more difficult if you remove the keys in a Samsung board. With a Mitsumi it doesn't make much difference, but if you are not cleaning between the switch tray and keycaps, why go through the trouble of pulling a single keycap. :-)

Anyway, leave the keycaps in place when looking at the membrane(s). If you want to do a deep clean later, then it's a good idea to have the keyboard backin plate properly together before you start pulling keycaps.