I got ripped off on a dead Amiga 4000

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that's how this seller is talking too.  like he doesn't know wtf.  also if you read the auction, and he DID have mouse and joystick ports replaced.  They're replacements and they look like they were properly soldered on and attached.  But damn I'm thinking if there's a jumper or a resistor that controls those, there's something messed up with it.  I have to find the info needed to replace mouse & joystick ports and look at it so I can diagnose.  I'm pretty sure that's what we're dealing with since yes, keyboard jumper just disconnected should do it.  Also again let me state I have a good, not tank, Amiga mouse along with the one that came with this 4000 so I know it's not the mouse.  I don't know what it needs.  There is a couple weird jumpers on the A4000.  This one I won't mention because I forgot and it's not the one but this one, CN404 is near the back and by the audio and video outputs and has no jumper on it.  But J975 is right by the mouse and joystick ports and has no connection to it and looking kind of like a place for some sort of power connection but I don't know.  Doesn' look like you're just supposed to stick jumpers there.  CN975 and CN976 are the mouse and joystick ports respectively.  And there isn't anything that looks like a resistor or and jumper spot near them really, besides the PAL/NTSC jumper.  My monitor is a Commodore 1960, so it can handle either just fine and I keep the jumper on NTSC.  I've tried seeing if that effects it anyway but it doesn't as you'd think.  It's just the only jumper close to the mouse so I tried it.  Nothing doing here though.  It's like either more likely mouse port is bad, even though it is this nice replaced one perhaps has come loose (CN975 and maybe CN976 too for joystick), or, this A4000/040 highflyer model happens to have the key hardwired to those in some way other amigas don't.  And you need to maybe solder a resistor in to hack around it or something.  That sounds too crazy to be true but it's anything worth thinking about right now.  It plays and loads games and apps so it's not like I can turn back now!

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*chip only with floppy and only highflyer card, then turn on + 2 mouse buttons held, then turned off and inserted the other daughterboard (zorro one) and boom insert disk screen finally appeared.  turned off,  then proceeded to put the ide HDD back on there and boom, workbench 3.0.  time to grab some 3.1 roms now and a bunch of other stuff for it

the real hardware issue was just that the cpu mainboard wasn't seated properly.  it came off during shipping and it's on weird plastic pegs that are meant to be easy for it to pull off i think because it gets unseated easily.  so to make it totally clear, the real thing that fixed this box was just making sure the cpu card was VERY perfectly seated.  it went out again and i went for the kind of hard to reach cpu card this time.  had to remove the HDD to get at it properly.  you can't seat it right just sticking your fingers in without removing the HDD which is directly behind it. there's not enough room.  still problems.  I really did find this aligator clip that's the right exact size and it turns and clicks perfect into lock and unlock.  and everyone is saying you can disconnect the key.  so it's got to be something wrong somewhere on the motherboard.  it says missing some stuff when workbench starts up but that's nothing to do with this because the mouse doesn't work in games either.

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seller says:

"I’m getting pretty sure there is the problem with the keylock control if the U975 functioning properly as the keylock controls the U205 74HC4066 keyboard control chip and the U131 logic chip and that U131 chip is sending a signal enable or disable to the pin 6 on U975 the that controls the mouse port, only I have to see the schematics and the chip layout to determined the correct action regarding the keylock configuration. As I remember in one position the key is grounding the pin 11 on U131 in other position it release the ground and then there is +5V flow. I’m pretty sure that the CN200 keylock connections middle pin is the ground and the two other ones are +5V so the pin 1 and 3 are the +5V it doesn’t matter if the cable is connected to the pin 1 and 2 or 2 and 3."

and

"If the buttons works on mice that’s means you have the +5V on port and the fuse is ok it is the FB975 (located just behind the port 2) it protects mouse ports the axis control is done by the shift register chip 74HCT166 U975. Try to press done this chip and as you holding at done try to move the mouse check is there any changes."

It sounds like he knows how to fix it but it's too bad if one of those chips is that corroded.  it can happen though.  i do not know anymore right now.  tried pushing down on that U975 chip while booting but that didn't do anything.  any suggestions on what cleaner to use that won't ruin circut boards?  i have this stuff from radio shack that's god awful.  everything you try to clean with it it just gunks up and they call it, electronic cleaner.  but i don't think it's actually safe on any electronics I know of.

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I have neither of those tools.  That would be cool if I did.  But all I do know, is contacts in that middle left region of this A4000 motherboard look a bit worn.  All I have is a Volt/Ohm meter that's kind of cheap and I think that's only really for testing power supplies.

Battery was replaced soon enough and right by battery is ok looking.

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I have neither of those tools.  That would be cool if I did.  But all I do know, is contacts in that middle left region of this A4000 motherboard look a bit worn.  All I have is a Volt/Ohm meter that's kind of cheap and I think that's only really for testing power supplies.

Battery was replaced soon enough and right by battery is ok looking.

The U177 chip, whatever that one does, has one of it's feet melted off.  It happens to be the chip right by the battery.  Maybe this guy didn't catch the battery replace in time.  Also the leads on the one I mentioned in the above post looks like crap.  New motherboard rev. B is what I need.  e-mail/pm if you got one.  I got buster chip part #390539-11, which is the later one I think.  So as long as you got the rev. B with the socket for the buster that's what I need.  And one that works of course.

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On Ebay, sombody is selling two Amiga 4000 motherboard.  One is $79 and the other is $59.

Barney

Disregard this:  the ebay auction says that the memory does not register.

totally man I saw those.  They are very shady.  Both of em he ripped the battery out.  I'm going to buy myself some Weller solder gear this afternoon at the computer store because I know if this thing is going to actually get fixed I'm going to have to do it myself the old fashioned way.  I see this guy has a wiring diagram in next post Haven't looked at it yet.  Looking forward to it though.  Too bad.  This guy took care of his motherboard.  But I may not have to worry because he may have another A4000 motherboard he's willing to send me.  I have a feeling he doesn't have a spare but he'll probably take it out of his 4000 and send it.  But I just don't want him to have to.  I mean I'll push him to send one if he has it but I'd be so satisfied if I resolder it myself.  If it's fried chip (this U175 or whatever), then that sucks because I'm pretty sure I'm not going to just find that chip somewhere.  It all adds up to needing a new motherboard unless there's really just a contact issue that needs a little metal to keep it going through.  You gotta be so careful.  This case is cool but what is REALLY cool is that Highflyer Expansion card has a Video Toaster slot in it, and the regular daughterboard, which sits above the Highflyer on this Miggy, only has the 4 Zorro III slots as normal A4000 has.  So whatever happens I have to keep this Highflyer Card and the case because otherwise, you can't fit both daughterboards in there.  We'll keep everyone posted.

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it's a 74HCT174, you should have no problem finding one. Digikey has one for a dollar.

Oh yeah!?  That's what I needed is someone to say what you just said.  I'm not a PCB expert I just can do this type of work when I have to.  So it's sort of a common chip I guess then.  I thought it was something like the Lisa or Super Buster where it's an Amiga exclusive.  This advice is VERY helpful for what I'm attempting this afternoon.  Thank you!

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FC74HCT166T is the identifier on the chip below that it says 323820D and KS59310PBY

I don't nee that other one I guess because that just controls the RTC.  I also need a new IDE connector to solder to the motherboard.  Looking for both these things at the site.  Cannot find the FC74HCT166T chip.

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Is it a DIP chip? See this:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-2099-5-ND

For the IDE connector, see this: (could somebody double check that to make sure it's the right one?)
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MHB40K-ND

yes those are the ones!  good job finding them.  it cross references with what's on the chip.  and that's the type of ide connector i'd solder in if I have to.  Because the floppy and IDE connectors are so close together though it might be a tight squeeze.  Still that's basically the part i was looking for.

Thanks

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Maybe someone has mention this before but..


Also check the CIA 8520 chips.  

The CIA A handles mouse and joystick ,keyboard signals.

http://www.natami.net/dev/Hardware_Manual_guide/node012E.html


They are the first I check if an Amiga goes crazy .

These chips has given me some strange errors over the years :madashell:

If they are socketed, try to switch them.


Happy hunting

Any idea how this chip you mention is notated on the motherboard (i.e. Uxxx)?

I bought a replacement for U175 which is a FC74HC166T, and it's exact part number is CD74HCT166E.  But it cross referenced with the exact # listed above there.  DigiKey.com is where I got it thanks to another poster a page or 2 back (the big schematic posts you'll see looking back).  These chips are cheap and if I get the right ones I can pay this shop to get them soldered in cheap probably.  I really suck at soldering and am only really able to solder wires or resistors into place.  Also I bought a better IDE interface because I'm sick of having to worry about it breaking every time I hook that part of it back up.  It's a grey one with the guides on the sides so you don't have to shine a flashlight and take 2 full minutes hooking it up.  Of course that would require desoldering the old one and getting it out first.

Which notation on the motherboard is this chip given that you are suggesting may be causing the trouble?

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The seller says that because I posted the Amiga I bought from him on this forum and his friend told him, he doesn't have to help me.  I got the computer on June 22nd and didn't post here until July 6th.  There aren't any working motherboards for the Amiga 4000 on Ebay right now and I just bought a new Amiga 4000 for $575.  Thanks to whoever told this guy I posted!

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As for this thread, it has chronicled ceaser's complete disassembly of the machine in what could be considered amateurish attempts at repair.  I wouldn't expect the seller to take responsibility for a machine that was pulled apart and poked at by someone who may or may not be qualified to do so, not that this seller had taken any responsibility in the first place.  No guarantee means no guarantee.

You're stuck up aren't you?  I didn't take anything apart until it was definite that it wasn't working.  This motherboard was crapped out when I got it.  That's just it.  I don't repair motherboards.  I don't desolder and replace chips on them.  I just did the basics.  Maybe you fix computers in an "amateurish" fashion.  WTF does that even mean?

I took $100 back from this loser of a seller because I wanted the case and the Highflyer expansion card and the Amtrade HD floppy drive.  He sold it as "working" and per Ebay rules, that means it was supposed to be "working" when I got it.  This chip didn't just suddenly stop working in the 2-3 days while it was in shipping.  He was stupid to sell it as "working."  You should always sell old hardware "as-is."  This guy wouldn't talk to me and I waited about 18 days before I posted about it on a forum.  I put the auction number because I don't have a good digital camera and there were good pictures on the auction.

I didn't get the option to get my money back and keep his computer.  That isn't how it works.  I only had the option to haggle for a long time or a short time for a partial refund.  And no broken computer is worth a lot of money.

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Hey I wasn't going to ever goto this post again because I thought I had fixed my problem.  I bought a motherboard and as soon as I get it all closed up and working again, it started a little tiny bit yesterday, but now there's this HUGE ear ringing audio interference.  I tried turning off electronics next to it and stuff yesterday and it stopped but just like anything broken it got worse.  Irony is that the guy who's motherboard I couldn't get the key lock problem fixed on (without me trying to solder in a chip that might not have even been the right chip) had actually had his audio connectors replaced.

So this is a different motherboard.  Battery has been removed by myself.  It was exploded when I got it.  And please don't tell me "oh the battery suddenly just releaked junk that wasn't there and it broke your sound."  Give me constructive advice on how to a) get those audio connectors off the other motherboard and solder them onto this one.  b) how to ground the audio connectors from this motherboard or SOMETHING so they stop getting interference from everything within 20 ft (maybe an unprofessional style fix that's worked for someone in the past without me having to completely resolder the new audio connectors on, but I know no matter what that's what I'll end up doing because it's looking like Amiga audio cards are hard to find.  At least I don't see one up at Fleabay, and I guess you already have to know specific models to buy from amibay, kind of.  I don't even know the brand of someone who makes one).

Man my luck really sucks.

http://amiga.serveftp.net/audio_repair.html

Is this what I actually have to do???

See it's both of them so it looks like that means some capacitor needs replacement maybe.  Maybe the audio jacks are just fine.

hey this says it happens regularly only on these boards and i got a A4000 rev. B not D or T
"A common fault exists with "classic" Amiga motherboards based on surface mount device (SMD) technology.
These are the A600, A1200, CD32, A4000D and A4000T."

that other motherboard was rev. C that i was working on before

from that link just above

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I am, but guess what.  I pulled out a speaker wire to do the old grounding trick, put a wire from a hardware screw on the case to a screw on a big power supply beneath the computer desk.  It buzzed still pretty bad.  So I loosed the screw on the opposite side to put another speaker wire to a different place to ground.  The loosening of those 2 case screws caused it to stop buzzing.  Not just a little.  I mean it's back to normal.  I assume this is going to need a full workup on all caps that deal with the sound if I want it back to original but instead I got what I wanted maybe... If it stays working.  I'm going to look for a really nice Amiga Zorro sound card and buy that and not use the regular Lisa chip audio again.

The battle with this odd machine is won again for now.