Status of 5x A4000.

[Turran]

Hi hi.

This is sort of an update to this thread: http://eab.abime.net/showpost.php?p=...postcount=3984

Here are the original pics from that thread.

http://www.grandis.nu/images/Pickups1_1.jpg
http://www.grandis.nu/images/Pickups1_2.jpg
http://www.grandis.nu/images/Pickups1_3.jpg
http://www.grandis.nu/images/Pickups1_4.jpg
http://www.grandis.nu/images/Pickups1_5.jpg

This thread is about the 5 working A4000. I can say that the 6th A4000 (without front) is all black. Apparently it was shorted in the RGB port some time ago and has been dead since. Only confirmed its demise and not tried to bring it back yet. The A2000 is also dead. Monitor is fine but gives me a headake (how could you sit for hours in front of those?). All keyboards but one working. The non working one was fixed a few days ago by replacing most of the keypads on the bottom of the keys, so those are all fine now.

So I have stripped them all down to parts. This was a very boring batch for me, because I love getting my hands on old dirty, messy computers and it brings me great joy to clean out every crevasse to make them look like new.
This batch was already so clean, I had not much to do. Not a spec of hair or bodily fluids anywhere. Not even inside the floppies

I started with putting 3.1 kickstarts in them all and started them up with OS3.9 to find any faults.

The only ones I could find was that 2 of them had bad audio ports. All the batteries were of course dead as well. In the RevB motherboards ( two of them ), one of the batteries had started to leak a little, but nothing on the motherboard. The other one was spotless clean, but no cream in the battery.
The RevC motherboards ( three of them ) all had Lithium batteries of course.

Another funny tidbit is that all the RevD motherboards looked like they had resoldered CPUs. In one, I found a white sticker marked with "Converted to 030" on it. You can not see it because of the flash, but its on the rightmost white sticker.

http://www.grandis.nu/images/A4000_converted_to_030.JPG

After a cleanup with IPA around the CPU, it looked a lot better.

A further inspection of the caps showed what was expected. They had started to leak. Especially around the RTC and Audio. I replaced all caps on all motherboards, removed the batteries and the bad audio ports.

This is the plunder!

http://www.grandis.nu/images/A4000_Plunder_of_caps.JPG

Then I ordered new batteries from Amigakit and waited for them.

For the audio part of the two that had glitchy ports, I ordered new ones from Farnell and put in. Should have gotten some yellow ones while I was at it. Remember that they come in pairs, so if you buy 5 or each like I did, you'll get 10 of each.

http://www.grandis.nu/images/AudioPlugs.JPG
http://www.grandis.nu/images/AudioInPlace.JPG

After I had soldered the first two and took those photos, I was reminded that the audio ports on the A4000 are reversed. The red is left and white is right. So I switched them around to match the correct markings on the chassi (R/L).

I then checked the PSU and original harddisks. These two made so much noise, it was hard to talk during dinner when one A4000 was started on the floor above us. WHOOOOOOO. Could not even hear the floppy clicking.

So all the fans were replaced at the same time as I checked the PSU voltages and caps. They all looked very good and clean though, so no replacing there was needed.
One had an ATX PSU built into the original PSU chassi, so that fan was mounted on the outside as it did not fit inside anymore. A common way of doing it.

I got 5 of my favorite 80mm fan, the BeQuiet Shadow Wings. Pushes enough air but is very quiet. Old ones in the back of the second picture. For being old and making so much noise, they were damn near spotless.

http://www.grandis.nu/images/A4000_Parts.JPG
http://www.grandis.nu/images/A4000_old_fans.JPG

Out with the original disks. Should be a 5th here but it had fled when I took the photo.
http://www.grandis.nu/images/A4000_old_hds.JPG
http://www.grandis.nu/images/A4000_old_hds2.JPG

Then I got 5 CF->IDE adapters on ebay and 5 converters for the power as the original floppy power cable does not reach that far back, plus I need it for the floppy =)

http://www.grandis.nu/images/A4000_CF_Power.JPG

Also found 5x 2GB CF cards for 2.5€ so I got those. Not the biggest but good enough for these.

Ok, Caps replaced on all motherboards. All PSUs checks out fine voltage/cap wise and have new fans.
On to solder the first battery from AmigaKit to the motherboard.

First thing I learn after soldering it on there is that the battery placement on the RevD motherboards are a different direction from the RevB motherboards, so the battery goes outside the motherboard and hits the chassi when putting the motherboard back. Not good.
Furtunatly, the legs of the new batteries are pretty long, so I could bend them a bit so that the Battery comes a few millimeters further in.

http://www.grandis.nu/images/A4000_new_battery.JPG

Second thing I learned was that someone had previously cut power from the battery to the RTC chip.
This is how it should look from what I gathered by measuring (on another of the RevD cards). The 3v from the battery should reach pin 18 on the RTC chip. In other words:
Power off: +3v between ground and pin 18 on RTC
Power on : +5v between group and pin 18 on RTC

http://www.grandis.nu/images/A4000revD_RTC.jpg

This is why it did not work on the first RevD card.

http://www.grandis.nu/images/A4000revD_RTC_aha.jpg

So, remove D181
http://www.grandis.nu/images/A4000revD_RTC_aha1.jpg

Scrape and tin a bit
http://www.grandis.nu/images/A4000revD_RTC_aha2.jpg

Make a bridge. This is a temporary one. I just used solder to bridge it later but no pics of that.
http://www.grandis.nu/images/A4000revD_RTC_aha3.jpg

Put D181 back on.
http://www.grandis.nu/images/A4000revD_RTC_aha4.jpg

Tadaa, cheapass multimeter. Not quite 3v but thats fine.
http://www.grandis.nu/images/A4000revD_RTC_aha5.jpg

With everything working on the first one, put it all together
http://www.grandis.nu/images/A4000_First_one_done.JPG

Put a sticker on there ("Caps/Battery/Audio Replaced 2013-12-01")
http://www.grandis.nu/images/A4000_First_one_done_2.JPG

Bit fuzzy, but what the heck.
http://www.grandis.nu/images/A4000_First_one_done_3.JPG

On with the front and chassis and we are done with the first one! Now it can go to a new home in a while when I decide to sell =)

http://www.grandis.nu/images/A4000_First_one_done_4.JPG

I'll probably post more pics of the others if I find anything interesting to show.

[Astrofra]

Wow.
Five A4000, working state, in a row?
Am I dreaming or is this a genuine C= treasure?

[mfilos]

What a lovely thread! Thanks for sharing Turran my friend. I really enjoy restoration threads and these A4000 had lotsa love Kudos mate

[altcomputing]

Why didn't you just put a battery holder (eg. from a dead PC mobo) in this rev. D motherboard together with a CR2032 battery? They need no diode to work with lithium batteries like rev. B motherboards, because they were factory fitted with lithium coin!

[Turran]

Pleasure! I really enjoy them as well. Fun to be able to post one for once =)

The other 4 are also done. In one of the RevB motherboards where the battery had started to leak a little, I could not get the clock saved. I found that the traces to two pads on U177 had been eaten up. When I tried to remove the chip and fix it up, the ground pin broke lose, so the acid from the battery had crawled up into it.

http://www.grandis.nu/images/A4000revB_RTC_Bleh1.JPG

I ordered some new ones on ebay and fixed the broken traces.

http://www.grandis.nu/images/A4000revB_RTC_Bleh2.JPG
http://www.grandis.nu/images/A4000revB_RTC_Bleh3.JPG

Note that this was to test continuity. I shorted the bit on the pad afterwards so that the legs of the U177 chip was flat on the pad, not on top of my wire fix.

Underside of motherboard where pin 18 should go. The green stuff in the hole is not acid. Its the green film that has melted from the acid, so I left it there.

http://www.grandis.nu/images/A4000revD_RTC_done3.JPG

The yellow is tape (forgot its name) that is heat resistant and does not melt. I thought it looked good and also keeps the wires in place. I was a bit worried that it might move and get +3v from the battery as its only a couple of millimeters between it and +3v.

In with the new chip and battery. Working like a charm.

http://www.grandis.nu/images/A4000revD_RTC_done1.JPG
http://www.grandis.nu/images/A4000revD_RTC_done2.JPG

Originally Posted by altcomputing

Why didn't you just put a battery holder (eg. from a dead PC mobo) in this rev. D motherboard together with a CR2032 battery? They need no diode to work with lithium batteries like rev. B motherboards, because they were factory fitted with lithium coin!

The last A4000 (number 6) is on its way to Finland to get locked at. It has no SYNC signals in the video port and none from Alice either. Also, Alice gets very hot, very fast. so I guess its shorted out and will need replacing. I am not 100% comfortable in soldering at that level to replace it though, so another person is checking out that one.


(We posted at the same time)

Another thing.. the RevD motherboards (Cost Reduced) already had lithium batteries which do not charge, so I should have removed the resistor on the battery from AmigaKit as it just lowers the voltage even more, hence why I only got +2.45v on the RTC chip in this picture:
http://www.grandis.nu/images/A4000revD_RTC_aha5.jpg

I thought about that after fixing those and went in to remove the resistor, but when reading up on the RTC chip, it only needs +2.2v to maintain the time, so I did not bother.

[FOL]

Originally Posted by Turran

Another thing.. the RevD motherboards (Cost Reduced) already had lithium batteries which do not charge, so I should have removed the resistor on the battery from AmigaKit as it just lowers the voltage even more, hence why I only got +2.45v on the RTC chip in this picture:
http://www.grandis.nu/images/A4000revD_RTC_aha5.jpg

I thought about that after fixing those and went in to remove the resistor, but when reading up on the RTC chip, it only needs +2.2v to maintain the time, so I did not bother.

Its a diode, should be 0.6v. Not sure why its so low for you.

[Loedown]

Originally Posted by Turran

The yellow is tape (forgot its name) that is heat resistant and does not melt. I thought it looked good and also keeps the wires in place. I was a bit worried that it might move and get +3v from the battery as its only a couple of millimeters between it and +3v.

Kapton tape.

The battery damage on A4000 can be spectacular, I had to repair one recently with about 15 mod wires.

Also have a look at the schematic of the A4000D and you'll see they don't need a diode *but* read the note beside the RTC circuit in the schematic.

[Loedown]

Originally Posted by FOL

Its a diode, should be 0.6v. Not sure why its so low for you.

If the CR2032 has been hanging around for a while it may have dropped its voltage, or if it were scavenged from a PC mainboard.