Closed A3640 & A2000 Repair plus a few others

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KGC210

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I tried to perform the SpeedGeek State mod on the A3640
https://www.amibay.com/showthread.php?19993-A3640-50Mhz!&p=266058&viewfull=1#post266058
But I ran into a few problems, pulled a few solder pads. I have repaired them, but I also had a couple of cold joints on U203, U204, U205, U207, U208 etc.
Before I fixed all the cold joints U207 ran quite hot compared to the other chips. I checked the chip in my programmer and reprogrammed it and it showed as fine.
But the A4000 still wont boot with the A3640 in. Luckily I put the 030 card back in and the A4000 isn't toast.

I have done a continuity test on all pins for the above mentioned chips and all are fine now bar the _TBI Line on U205 (Pin25) as the schematics don't show where it goes to?

I have tried a different 040 in the board and still no boot so I am at a loss as what to check next as I don't have a scope or anything.

Re the A2000.
I bought it with no video display output.
When I got it there was a broken track on the video out connector, I repaired that and got the board working. There was heavy battery leakage. I cleaned it up with citric acid. The CPU and ROM socket quickly began to oxidized up again and was hit and miss working. I replaced both the CPU and ROM socket. But I caught a track under the CPU while removing the socket. I have repaired the track but the system still wont boot.
Sometimes I get no video signal at all on my monitor. Sometimes just black, odd occasion I may get White or a Pink / Aqua colour very rarely on boot.
Again I am not sure where to go next with it :(

I would also like to mod the A4000 to take 64MB of RAM on the motherboard as per https://www.amibay.com/showthread.php?57613-64mb-fastram-to-your-A4000-mobo&highlight=64mb+a4000
I have burnt the GAL, got 4 x16MB Simms, being double sided ones I also have 4 new upright simm sockets to replace the slanted ones. But due to my previous "repair" efforts mentioned above I would like someone to do the actual soldering for me please.

I built the 040 - 060 adapter but if someone does the above work I would prefer to send it along to make sure I have built it correctly as well before I plug it in. I have a rev 6 CPU for it.

I can supply pics of my cockups to give you a better idea and what's going on.

I would prefer UK / Europe work due to costs of shipping and possibly import costs etc.

Thanks Will
 

omegamsx

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Re the A2000.
I bought it with no video display output.
When I got it there was a broken track on the video out connector, I repaired that and got the board working. There was heavy battery leakage. I cleaned it up with citric acid. The CPU and ROM socket quickly began to oxidized up again and was hit and miss working. I replaced both the CPU and ROM socket. But I caught a track under the CPU while removing the socket. I have repaired the track but the system still wont boot.
Sometimes I get no video signal at all on my monitor. Sometimes just black, odd occasion I may get White or a Pink / Aqua colour very rarely on boot.

Your CPU is probably not starting. The random color on some cold boots is just the OCS chipset (denise) having random register values. These should be reset by kickstart in about one sec, but isnt when the CPU doesnt start. Check /RST and /HLT lines on the cpu. /RST should pulse high-low-high, while ctrl-a-a or power on. My guess is that /HLT stays low in your system. That is the chipset (agnus/gary) detecting something wrong with the busses. In about 90% of cases, it is one of the address or data lines going from CPU to the rest of the board. Do a continuity check on ALL address and ALL data bus lines from CPU pins (CPU inserted) to BOTH directions: the KS ROM and the Zorro bus (cpu slot is easy access point). If all check ok then check all other lines to/from CPU. A logic probe greatly helps in the bug hunting process :)

I can repair the board for you, I'm located in the Netherlands (y)
 

KGC210

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A3640 and 040-060 Adaptor with Rev6 CPU sent to bebek for repairs / checking.
Will PM tracking number.
 
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