A2630 + Big ram + 50mhz FPU ok?

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Don't Panic. Please wash hands.

    fantastic! thanks so much. I really appreciate your help. Now to find out if it actually was worth it! If not I'll be happy with 25mhz fpu.. although a buddy of mine said that if the 50mhz doesn't work.. if I use the 50mhz 68882 with a 33mhz crystal it would act like a 33mhz so only a minor additional purchase to get it back within the specs of the documentation.

    Hey there, so I finally got my local repair guy to get those chips removed.. but now when it turns on the system will not power up at all.. no fan or anything. if i remove the card the system will boot fine.


    i have the 2mb jump (j301) and with or without jumper just nothing..


    The technician seemed to do a good job.. just wanted to see if maybe i left something else out in the process of getting this card to work properly..


    Feeling a bit defeated right now.. god i hope there is some step i just missed..


         

    So the 2630 is running fine without BigRam2630, but does not start with it connected?


    There is no difference that the BigRam2630 needs to make between a 2MB or 4MB-equipped card. So my first Q would be: Did you send both cards to your technician?

    Hi there, no i haven't installed the big ram, this was just to see if the card itself would work with the 2mb jumper (J301) active.


    I only have one A2630. I figured if it won't boot without the big ram it won't boot with it. Wanted to start at the most basic level

    Jumpering to 2 meg should do the trick. However, please carefully inspect the traces on the bottom side where your friend has done the soldering: It is very easy to damage a trace that's still needed for the remaining RAM.Not a big deal - as easy as it is to damage such a trace, it's also easy to repair it with a jumper wire.

    That's encouraging. here's what the back looks like. maybe you can see some points of interest? i really don't know how to follow the traces of such circuits as i usually can see the traces coming off a point for less compact designs.


        


    I'll take it back to him and see what he can do. I have to say it was obviously super disappointing to take this in and have this work done, pay the guy and come home to it not working. he's done right by me in the past though so I know if I can come back to him with some changes he'll do them free of charge and this was a tough job (as you know). He ordered a special tool to help extract them because of how close the pins were together.


    Thanks,
    Caleb

    One spot is obvious: The via of the first corner pin is ripped off:

    This may or may not be the cause, but it's a first hint.


    Traces on the 2630 are hard to follow, as they are on the inner layers (2630 is a 4-layer multilayer board). The good news is that schematics (and even PAL sources) of the 2630 are open, so given enough time, you can verify each and every connection. Also, with the card still running w/o memory enabled, there may be a chance to access memory and see if it's an address or a data line that's failing. Did you ever use a memory monitor like CMon or Megamon? If so, I could check the PAL equations to see if the memory is still visible to the CPU, even if jumpered to be non-autoconfig (anyone following along may help out - I'm very busy right now).

    Thank you so much Jens for your insight! I can ask around with some folks I know in the States who might be able to help out as well.


    There's no way I can fix this myself without likely doing more harm than good. I'm desperate to get this card working again! I'm not saying it has to be immediately, but eventually.


    I believe that trace was likely the cause of the first attempt he did to remove a chip without the special tool he got to remove the others.


    I will first take this back to him and see what he thinks. Having the schematics should be a good first step! He's a seasoned repair person though I do throw him lots of curve balls like this that fall outside his usual customers requests.

    A little more.. So the fact that the A2000 will not power on with it in is because this is a short? or because of a lack of voltage completing the circuit? I'm just trying to make sure I can wrap my head around how the A2000 is reacting to the damage.


    Are there any other jumpers I could / should try for further diagnosing? J303 looks like it would bypass all the memory? Would this effectively also bypass the big ram?


    I want to proceed cautiously. it's very scary to flip on my A2000 and have it not power up at all so I don't want to abuse it's safety mechanisms as I realize had something gone worse maybe this could have done damage to the entire system.

    "does not power on" is a new descriptoin - or I didn't read your original post sufficiently attentive :-) The A2000 PSU will not power up if there is a short. So if the power LED of the computer does not turn on at all, you're looking for a short, yes.

    If there is a short that the power supply detects (and won't start because of that), the jumpers won't help. If there is only a short in some address or RAM control line line, you may be lucky and the jumper helps. If the short is with one of the data lines, switching RAM off with the jumper won't help either, because data lines are not buffered between the CPU and the RAM chips (after all, that's the reason why you're physically removing half the chips).

    OK So this is what we observed. no silver bullet found to find the short. I'll reach out to folks i know in the states that could help but if you could check this out and share any insight you have about this specific card, it could go a long way to bringing this back to life..


    https://youtu.be/fQWwlyGb_CI


    I'm just so discouraged that what i thought would be a safe and easy operation could result in killing the board.. I thought through hole boards were fairly straight forward..

    I've sent this to someone I know has some experience with vintage hardware and amiga stuff. Jens can you verify though if that capacitor testing looks right? is that normal to touch both sides of all those caps. i don't have a second A2630 to test against.

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