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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: koaftder on January 20, 2006, 02:42:26 PM
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Ive managed to piece together an a3000 over the course of a year. Its got many problems though.
The video is corrupted. Lots of evenly spaced vertical lines, which flicker on and off in little sections. The cursor skips around when you move it. All this pretty much goes away if you torque the pcb on the left side. wb seems to run fine, it doesnt crash at all, and applications load properly. The keyboard does not work at all, and if i go into prefs and click in the kb test box, it constantly outputs the character '8' There is a switch on the underside of the kb, with 2 positions, "a" and "x" which i assume is for AT or XT modes. Strange, as the kb has the amiga logo in the upper left corner, but there are no "Amiga" keys. It's laid out like a standard oldschool PC keyboard. it's model# is sk-8831B-2e, serial m930319859.
I'm concerned that it's not the right kb for this machine. ( i've got a spare a1000 kb, do you think i could wire it up to the a3000? )
i noticed that a lot of chips have become unseated, i pulled them all and cleaned all the contacts on the chips and their sockets and reinserted them. The battery on this machine had leaked all over the place, i clipped it out and cleaned the residue off the pc as best i could with isopropyl alcohol and qtips. There is some corrosion on some parts, mostly some resistors, some capacitors, i was unable to clean under several 74 series logic chips in that area. The lacquor on the pc seems to have done a good job of preventing the traces from getting corroded. The traces look good.
Is there a service manual for these machines avaiable? I used to fix tv's, and the service manuals are full of useful information. I could spend the rest of my life poking and prodding this thing with the scope.
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Koaftder,
Yes, there is an A3000 service manual available. They show up from time to time on eBay (look for merchant Centsible Software) or you might contact Software Hut and ask to buy or get a copy of the manual. There is a copy of this manual on eBay (http://cgi.ebay.com/Hard-to-find-Amiga-A3000-Factory-Service-Manual_W0QQitemZ8753433017QQcategoryZ4598QQssPageNameZWDVWQQrdZ1QQcmdZViewItem) right now.
You comments about the various problems is not unexpected given the age of the parts you have. The single worst item was the battery. I'm glad you removed it. Be sure that all corrosion is gone from that area!
Something else that would be of great use to you would be a product called "Amiga Analyzer" which was a hardware / software test kit used to diagnose many problems on the A2000-A4000 series using WB2 or 3.1. If you can find one of these it will be most useful to you in repairing your old A3000.
Good luck,
Regards,
Ltstanfo
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Amiga analyzer? I think I have one of those around.
Never used it, so don't even know if it works :(
Could be persuaded to part with it.
As I recall, it had a disk with proggies on it. WIll look around tonight.
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Try finding a real Amiga keyboard (or PC keyboard w/ Lyra interface) and see it solves anything. It sounds like you have an AT PC keyboard that's been modified to work with Amigas, but the modifications, or the keyboard in general, have failed/decayed over time.
The BBoAH (http://www.amiga-hardware.com) has info on some of these modified PC keyboards that might be useful.
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ltstanfo wrote:
Koaftder,
Yes, there is an A3000 service manual available. They show up from time to time on eBay (look for merchant Centsible Software) or you might contact Software Hut and ask to buy or get a copy of the manual. There is a copy of this manual on eBay (http://cgi.ebay.com/Hard-to-find-Amiga-A3000-Factory-Service-Manual_W0QQitemZ8753433017QQcategoryZ4598QQssPageNameZWDVWQQrdZ1QQcmdZViewItem) right now.
You comments about the various problems is not unexpected given the age of the parts you have. The single worst item was the battery. I'm glad you removed it. Be sure that all corrosion is gone from that area!
Something else that would be of great use to you would be a product called "Amiga Analyzer" which was a hardware / software test kit used to diagnose many problems on the A2000-A4000 series using WB2 or 3.1. If you can find one of these it will be most useful to you in repairing your old A3000.
Good luck,
Regards,
Ltstanfo
Well, i got the jitter fixed and the display working nice as long as there was constant pressure on the denise chip. Lots of corrosion in that socket. Thats what was causing the video problems. I cleaned it several times with a sewing needle, scraping off the crust, wasnt doing the job. I started cleaning with a pick, and on one of the socket pins, it collapsed ): Wasnt really a pin anymore, jsut a stiff piece of corrosion. Oh well, wrapping wire to the rescue!
Thanks for pointing out the manual on ebay, i put my bid in, hope somebody doesnt snipe it on the last 30 seconds!
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Matt_H wrote:
Try finding a real Amiga keyboard (or PC keyboard w/ Lyra interface) and see it solves anything. It sounds like you have an AT PC keyboard that's been modified to work with Amigas, but the modifications, or the keyboard in general, have failed/decayed over time.
The BBoAH (http://www.amiga-hardware.com) has info on some of these modified PC keyboards that might be useful.
I finally got the kb to work. The soldering job that was done on it was hardcore sloppy. From looking at the joints, its obvious that the iron wasnt hot enough, and the person who did this didnt even make sure the wire was flush with the pins when they did it. Two of the wires that went from the microcontroller to the keyboard broke their joints when i examined the underside of the pcb. There was solder spill all over the kb's pcb. I coudnt have done a worse job on that if i had just drank a 6pack and was smoking while doing it.
I replaced all the wires and redid all the joints, works great now. Dang thing probably got messed up during shipping.
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i passed through these nightmares recently when i take a secondhand a3000. at boot time the screen opening in yellow and the hd was not starting to load the os, and when i was pressing here and there sometimes was booting normal for a while and so on. after a month of cleaning and change of some registers the amiga was stable for longer periods and then i observe that when i was pressing the mobo at left and back area near the vga output the image on the screen was leaving and coming and the colors was going mad. i remove all the ic's of chip memory, the first megabyte,8 ic's was secondhand with soldering on! i clean everything and seens then all the problems stoped and the amiga is more stable than i am :)
now i'm searching for a3000 stuff to upgrade her :)
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amije wrote:
i passed through these nightmares recently when i take a secondhand a3000. at boot time the screen opening in yellow and the hd was not starting to load the os, and when i was pressing here and there sometimes was booting normal for a while and so on. after a month of cleaning and change of some registers the amiga was stable for longer periods and then i observe that when i was pressing the mobo at left and back area near the vga output the image on the screen was leaving and coming and the colors was going mad. i remove all the ic's of chip memory, the first megabyte,8 ic's was secondhand with soldering on! i clean everything and seens then all the problems stoped and the amiga is more stable than i am :)
now i'm searching for a3000 stuff to upgrade her :)
With the zip ram, how did you install that? Ive got 8 chips too, but when i put them in, they dont register. All it sees is 2mb chip. Ive tried both orientations, no luck. They dont get warm either. Ive got them spaced like many of the pictures show on amiga-hardware.something. Ive looked all over on google, but havent found a doc explaning where to put them, how to orient them. Man, i hope i didnt fry this zip ram chips.
Work bench pops up, says it's got a meg or something free graphic memory, and 0 other memory. Sysinfo says ive got 2mb chip. I didnt want to ask on a.org how to install ram on jump, as i know it's been discussed probably a lot, and it annoying when people ask stuff without looking around first, but i', stuck on this one.
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well the ic's was already there, i was not the one that put them there as extra ram. a friend of mine who has also an a3000 (MrZammler) told me that probebly someone took the 1mb chips of a dead a3000 and put them on this amiga in the extra connectors. he also told me that in older a3000's the chip ram was solderd on the mobo, so for this reason there was the soldering on the pins! i'll try to take a foto of the area around the chip ram and i'll send it to you, if this can help you in someway.
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Looks like ive accomplished my goal of reviving the a3000. The denise socket was badly damaged from battery fluid, so i removed that scoket, and soldered the denise chip right to the board. I messed up a trace for the vertical mouse signal, but i worked around it.
So no more video corruption, or messed up random mouse events. I repaired the keyboard, so thats in good order as well now. Ive had the system up for about 24 hours now, and have used it for several hours, not a single guru.
Now that it's up and stable, i'll work on upgrading it. I plan on the following:
Better video board
3.1 roms
max out the memory
Ethernet board
Accelerator
HD Floppy
Build a nice wood case for the machine
Spinner rims, etc
I submitted some pix of the repair process, i'm guessing some people will cringe at the sight.
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Here is the page.
http://www.l8r.net/technical/t-3000ram.shtml
What is not said on the page:
Zip RAM has a notched off corner on the top edge. This notch faces LEFT, away from the mouse port area. You start in Bank 0, and the lower left position. Fill in all eight of the Bank 0 slots. You now have 4 megs installed.
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Amiga4k wrote:
Here is the page.
http://www.l8r.net/technical/t-3000ram.shtml
What is not said on the page:
Zip RAM has a notched off corner on the top edge. This notch faces LEFT, away from the mouse port area. You start in Bank 0, and the lower left position. Fill in all eight of the Bank 0 slots. You now have 4 megs installed.
Well, i followed the instructions, and *yay* i got an extra 4mb of ram like you said. I had the chips in the right slots apparantly ( i plugged them in as i saw on a few of the motherboard scans on that amiga hardware site ), but they were in backwards. I should consider my self lucky that they are not fried. I didnt have a notch on the side of my chips... It's got a slope on one side that runs the length of the chip. The lables of the chips in the correct position face towards the front of the machine, along with the slope.
So now i've got 2mb chip and 4mb fast, thanks for the help!
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ZIP chips seem to be quite scarce, does anyone know where I can buy some, or even what a decent price would be for them please?
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gizmomelb wrote:
ZIP chips seem to be quite scarce, does anyone know where I can buy some, or even what a decent price would be for them please?
Softhut seems to indicate that they have them in stock. http://www.softhut.com/cgi-bin/test/Web_store/web_store.cgi Though i cant confirm this... Ive emailed them twice and never got a response. Other people seem to have gotten chips from there. I suppose i could call them, though honestly i havnt put any effort into trying to get it.
*hint* Would be nice if amigakit carried the chips, id buy from there for sure, they seem up to date and have an excelent record as far as i can tell. Then again ive never heard anybody complain about softhut either, my emails probably got drowned out in the spam.
Catherder i beleive posted a thread calling for peoples zip chip model numbers. He said that the chips are avaiable from IC vendors as old stock. They have minimum orders, so you could buy a bulk lot of the chips for a probably 1k or so. If you did this, and started dumping them on ebay, who knows when markit saturation would be reached, probably before you sold them all, so you would sit on a pile of chips and end up having to dole them out slowly to make your money back.
Ive got 4mb of fast ram on my a3000, and ive never run out of memory with the apps i use, so topping off the ram isnt a big priority, but for reasonable price i'd do it, and probably get a new kick rom as well.