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Author Topic: A few questions on the A1000  (Read 3003 times)

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Offline save2600

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Re: A few questions on the A1000
« on: March 29, 2009, 09:46:04 PM »
The trace wires you are observing... are they just toward the rear of the daughterboard? If so, there are 4 PAL chips that many people have wired between each other. The grounds that is. FWIW, I have owned about a dozen A1000's since 1986 with various internal and external expansion devices and not once have I ever needed to perform this supposedly necessary grounding mod. Same with the expansion bus power supply ground mod. BUT... maybe users of the sidecar or some other peripherals "needed" the extra help at some time.

RE: those 252180 & 252179 chips, your computer wouldn't boot at all or show the Kickstart icon upon startup if they were bad. I'd leave 'em alone or maybe re-seat them is all (same with all socketed chips, especially the CPU. Re: the faux Kickstart chips under the disk drive, I've got both CBM and what looks to burned, as you've got sitting there. Same revisions and part numbers.

The ceramic/gold/mil spec chips were in the original A1000's. Look for the revision number at the end of the chip numbers. You'll see R4, R8, etc. Later revision will be the plastic ones as you've noticed. You might even have the Denise that allows for EHB modes if it's late enough :-)   Originals did not do Extra Half-Brite.

Oh - and are your drive ribbon cables okay? If those go bad, were crimped because of peripherals, female connectors no longer tight, etc., they can cause a drive to act flakey. This just happened to me involving an A2000 drive I thought was bad. Turned out the fault was with the cable!
 

Offline save2600

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Re: A few questions on the A1000
« Reply #1 on: March 30, 2009, 12:35:46 AM »
Boy is that an ugly daughterboard! lol   Since you don't have all the stuff the previous owner had hooked to it, I guess I'd be taking a look at the component side of the daughterboard to see if there are any bad traces. Otherwise, not sure why there are soooo many jumpers running across like that. If it were my system, I'd start by removing ALL of those jumpers if not just to return the system to cosmetic 'normal'. Who knows, maybe some of them are causing you booting and/or other grief.

FWIW, I've got the mil-spec/gold, whatever you want to call them 8520 CIA's in one of my machines and the 2 chips below them look exactly the same as one of mine as well. Square sticker w/ part numbers covering the eprom window.

What's that red wire to the left going to? Looks like it leads to the power supply. That's definitely out of place, as are the white and yellow wires seemingly coming off the daughterboard. The blue wires, I can barely see, but I can tell you they are not part of the usual grounding mod done to these. Nor is what's going on in the middle of 'J', and 1/2 of the other wires.   :-o
 
 

Offline save2600

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Re: A few questions on the A1000
« Reply #2 on: March 30, 2009, 04:19:04 PM »
Wow - that daughterboard of yours is fubar'd alright. The wires added to the component side are fine(typical ground mods). And probably necessary now that the ground pin of PAL 'J' has been compromised on the solder side of the board. Maybe that chip was replaced at one time and they were not very discreet with their soldering techniques. The jumpers on top may be necessary IF they screwed up the traces under those PAL's, but I doubt it. If those PAL's were replace at one point, they surely didn't socket 'em(bad, bad move).

Either way, since that board does not allow your computer to boot as-is, why don't you remove ALL of the extraneous wires up top(solder side)? I wouldn't be surprised if it would work then. OR... get yourself one of DJBase's Kickstart adapter and ditch the daughtercard altogether(I'm not positive some leads of his adapter board do not solder to the daughterboard however). Or are two leads soldered from Kickstart adapters necessary ONLY if you leave the daughtercard in? I've got one coming, along with a Kickstart 3.1 chip that I may not end up using thanks to Ratte's Twinkick  :-)  

I do have a DKB Kwikstart board with 1.2 ROMS that -needs- 2 wires soldered to a couple of PAL's that I am no longer using. I just thought of that. I should have tested the theory before putting the A1000 all back together  :-(  


 

Offline save2600

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Re: A few questions on the A1000
« Reply #3 on: March 30, 2009, 04:38:09 PM »
I'm going to have 2 Kickstart ROM adapters for the A1000 here soon. A Kwikstart w/ 1.2 ROMS (already have) and DJ's, which I'll either put a 1.3 or 3.1 ROM in.

I've got a conundrum of sorts going on here with the Kwikstart as it provides the only means of extending the pins of my DKB Insider! lol  The Insider will NOT fit in the A1000 without an extender as it sits too low and interferes with the internal floppy connector.  Might just as well sell both together then. NOT having anything external on an A1000 is nice, but the Insider is just 1mb. Paired with the Kwikstart though, that gives your machine 1.76mb ram, assuming you have a 1050... more than enough to play most of the classic games  :-)   LMK by PM if you'd be interested in the pair, else I may just end up selling them separately.