Amiga 500 non working keyboard with extra ram attached, Gary, 2 blinks caps lock.

[CoCan]

Hi guys,

I would appreciate some help.

Amiga 500 revision 5 with non working keyboard (works very occasionally), Amiga OK otherwise.

Caps lock led sometimes blinked twice, sometimes stayed on.

After cleaning keyboard, membrane, connectors etc, trying a different keyboard and reading some posts on here I traced the keyboard problem to the Ram Expansion.

Ram expansion is trapdoor type with the part that also attaches to Gary socket.

If i unplug ram expansion and put Gary back on mobo, keyboard is ok.

I’ve attached some pics.

The part of the ram board that attaches to gary is a bad design and doesn’t feel that it goes all the way in the socket due to Gary pressing against CIA chip (Attachment #1). However it’s worked OK like this for many years.

Ram board looks ok to my non-expert eyes, possibly 2 burnt out resistors near battery? (2 small ones to the immediate right of the horizontal chip, Attachment #2) battery looks fine. Only other problem I saw was some green oxidisation on some of the pins (Attachment #3, but continuity tested fine.

Extra ram from the ram expansion appears to be working and available to use.
354176 (bytes? 345.88k?) of free memory on WB 1.3 after boot with ram switch off. 1926976 (1881.81k? ) free memory on WB 1.3 with ram switch on. So is this ram expansion 1.5mb?

The keyboard worked fine with this ram expansion in the past, problem happened whilst in long term storage.

My questions are

1) What size ram expansion is this? Originally I thought it was 512k but looking like 1.5mb? I bought it new in early 90s but really can’t remember. I can’t do AVAIL command due to non working keyboard when it’s attached. I took close up pic of the chips (attachment #5)
2) Is there anything I can try to get the keyboard to work with extra Ram attached.
3) If I can't fix it, is it something someone with the knowledge possibly can? or at least use the chips etc off it? Or is it destined for the scrap heap.

Thanks for reading this (if you did)

[emufan]

those ram expansion with gary adapter, were those with 1.5/2mb. the 512k cards did not need that adapter.
i'm no hardware geek, so i cannot say much about the problem. maybe some weak solder joint. or one of the contacts needs more cleaning.
there was a keyboard tool on one of the workbench disk, which let you use the mouse to type text
into a shell/cli or text program, but i cannot find it on my wb 1.3 disk.
--> on Extras 1.3 disk -> Tools -> KeyToy, but the typing with mouse does not work. hmm
i was sure it does work somehow :/

btw. it was always a good advice to remove/desolder the battery, before it starts leaking.

[CoCan]

Hey ,thanks for the reply. I no longer have the 1.3 extras disk, I have the DMS though so will try to get that on a floppy using my 1200 and go from there.

Yes I will get onto the ram battery, I'm just grateful it hasn't leaked whilst in storage

long term storage kills AMIGA's...........

Use them,,,,,,,,,,,

[Allen1]

The "possibly 2 burnt out resistors" are diodes probably 1N4148 or something similar and with the black polarity band and their small size they just look that way


"Ram board looks ok to my non-expert eyes, possibly 2 burnt out resistors near battery? (2 small ones to the immediate right of the horizontal chip, Attachment #2) battery looks fine. Only other problem I saw was some green oxidisation on some of the pins (Attachment #3, but continuity tested fine."

[CoCan]

After much messing, managed to get Keytoy on a floppy, but it doesn't work as a virtual keyboard for me either.

Managed to find software called Jakeboard on aminet that has worked though and lets me type with the mouse. great stuff. Here's the AVAIL results:

> AVAIL
Type   Available In-Use  Maximum   Largest
chip   413840    109392  523232    397408
fast   1421008   144456  1565464   1415000
total  1834848   253848  2088696   1415000

So 1565464 / 1024 = 1528.8kb = 1.5mb yes?

@Allen1 Many thanks for that info! Thought they looked a little odd, haha.

[emufan]

Originally Posted by CoCan

After much messing, managed to get Keytoy on a floppy, but it doesn't work as a virtual keyboard for me either.

Managed to find software called Jakeboard on aminet that has worked though and lets me type with the mouse. great stuff. Here's the AVAIL results:

ok, cool - maybe i was using a different tool, but i was sure something like that i was using

> AVAIL
Type   Available In-Use  Maximum   Largest
chip   413840    109392  523232    397408
fast   1421008   144456  1565464   1415000
total  1834848   253848  2088696   1415000

So 1565464 / 1024 = 1528.8kb = 1.5mb yes?

yep, thats it.

@Allen1 : good eyes

maybe some component on the gary adapter burnt too. just take a look, next to the 2 chips,
there might be at least one other part (2 pins)..

[CoCan]

@emufan, thanks a lot for your help and confirmation of the ram amount.

Took a pic of the gary adapter which I've attached. Hopefully it's big enough (might have to zoom) but to my eyes it's looking like that ceramic cap is busted! Anyone agree?

Never changed a cap before but that one doesn't look too difficult, anyone know if i can buy them in less quantities than 100 pieces, and will any disc ceramic cap with 104 written on be ok, are they all the same?

Many thanks.

[Daedalus]

Yep, it's damaged alright, though without measuring it it's hard to tell if it's causing any issues. Check if there's any resistance across it - it should appear as open circuit when measured for resistance. If it has a low resistance, it's bad news. If it's open circuit, it could still be damaged but not very likely to cause problems.

It should be very easy to change however. 104 is the standard notation, it means 100nF (100,000pF - 10 with four 0s after it). Farnell have them with a minimum order quantity of just 10, though I think there's a delivery charge for such small orders (84p+VAT).

[CoCan]

@Daedalus, thank-you very much for the info.

Yep I might just take a gamble on replacing it and hope for the best, but will check it with mutl-meter later

Thanks again, you've been really helpful.

[CoCan]

3 months later update (other things got in the way).

Changed the disc capacitor on the ram gary adapter a few weeks ago but was scared to try it till now, haha.

Just booted her up with the ram attached and keyboard seems to be working! (other than 1 key) but thats a lot better than before. Also no blinking caps lock.

It might be because I've not plugged the 500 in for a few months, but so far, it's looking like changing that disc capacitor actually worked. I can hardly believe it.

I'm very grateful for the help emufan, allen1 and daedalus, I couldn't have done it with the advice and input. Thanks

p.s. If i remove the battery from the ram board before it starts to leak, it won't cause any other issues will it? is it just for the clock (which doesn't keep time anymore anway)

[idrougge]

Removing the battery is harmless.

[CoCan]

Thankyou idrougge

[CoCan]

Bloody hell. me again.

The problems have returned, but not happening as often. Baffled.

A500 was running flawlessly for 2 days since my last post.

Last night I removed the ram expansion to de-solder the ram battery, when I connect everything back up, the problems started again. (I have removed ram board and adapter several times to make sure everything seated properly).

Behaviour is slightly different this time, and doesn’t seem as bad, but as I say, baffled.

I’m an almost total hardware novice as you might have guessed. Have noticed before what looks like 2 burnt out resistors on the 500 mobo just above keyboard connector, but they seemed to be related to the Serial port (never used it) and as the problem went away when ram extension disconnected, I didn’t look into it further.

But I would appreciate if anyone can look at the pics, confirm to me if the resistors need replacing, if they are related to the keyboard or serial port and what to replace them with (I understand the coloured bands signify the value, but you can no longer tell). I had a look at a 500 mobo diagram in the past but it was way over my head.

1st attachment is a wider pic for context and to show the other similar resistor to the left, 2nd pic is zoomed in to the 2 resistors in question.

Another possibility is removing the ram battery caused the issues to return, but not likely? I had a look last night for replacement batteries (3.6v 60mah ni-cd) and they seem hard to find but were a couple of sellers on ebay. If I do replace the battery I will use wires and have the battery away from any components if poss to prevent issues down the road.

Of course it might not be related to any of this, just the act of moving things around due to the age of the hardware.

[CoCan]

I took out the CIA chips, cleaned and swapped them, seems to be behaving itself for now.

[idrougge]

If that's the case, whatever burned those resistors must have damaged the CIA as well.

[CoCan]

Well, it's still misbehaving some of the time, but it is a lot better. Capslock light flashed or stayed on a couple of times, and keyboard just stopped working quite a few times whilst working in shell. Seems to be when I've changed disks, or moved the keyboard slightly (not put everything back together yet).