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Thread: How Dumb Am I!? ^_^ Dead A4000D

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    Lazy Gamer Frederic_Freakazoid's Avatar
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    Default How Dumb Am I!? ^_^ Dead A4000D

    So.. years ago (Link) I had gotten some great feedback regarding the RTC/Battery area of my dead A4000D motherboard. The problem is, I don't think the one thing people (including the late great Glen) kept pointing out was ever addressed (even though I'd kind of said it was over a year later). Can someone tell me specifically the traces that obviously need repair?

    I think I psyched myself out, to think it wasn't the problem, by testing with a multimeter, per some guide, but not actually knowing what settings constitutes a correct signal. Plus I am now way more confident with soldering/desoldering than I was back then.

    Exhibit A - "before"


    Exhibit B - "after"
    Last edited by Frederic_Freakazoid; 12th February 2018 at 17:41.
    "Progress is being made if each mistake you make is a new one."

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    8 Bit Dreams DjCook's Avatar
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    need also remove chips and clean under them
    Retro computer hardware & repair in Germany

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    CrazyBob's Avatar
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    Yep, what DjCook is saying is correct... I had a similair repair:

    Click image for larger version. 

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    Measure all via's in that area, also the ones underneath the simm-sockets...
    Last edited by CrazyBob; 10th February 2018 at 21:39.
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    Hello,

    ...and be prepared to remove the simm sockets, because leakage from battery can affect this area under the sockets.

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    Lazy Gamer Frederic_Freakazoid's Avatar
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    *nods to all of the above* I just figured since people told me repeatedly (made embedded link obvious above), just from those pictures 4+ years ago, that I needed to repair traces, that something was glaringly obvious. Such as the bit of puffy gook to the left of the battery's spot in the "before" pic. *Somewhere* I had even read that a specific trace could cause boot issues (Edit: here it is), but for the life of me I can't find that article online again. I may first just tin those traces. I love all the resources available online (Edit: rereading them just makes me feel even more dumb for not trying any of this repair sooner).
    Last edited by Frederic_Freakazoid; 12th February 2018 at 18:59.
    "Progress is being made if each mistake you make is a new one."

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    CrazyBob's Avatar
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    I'm not sure what your approach is? Just tinning the 'obvious' traces is most probably not going to work.
    Total cleanup and measurement would be the best approach...removing chips (other components like SIMM socket and resistor array) and measuring all via's and traces in that affected area.

    One other thing, the acid from the battery and the capicators can get between the PCB layers, which is the white discoloration of the green PCB (4 layers for this board).
    Therefore it would be wise to measure the whole trace instead of short sections...

    Having said that, good luck with the repair and I really hope you can get it to work
    => Commodore A600HD/40 <=
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    Lazy Gamer Frederic_Freakazoid's Avatar
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    So far my approach is ask questions every 3-5 years online, get inspired, then ultimately do nothing.

    Thankfully I DO have some occasional free time now where I won't be interrupted by a (former) wife/gf and/or daughter.

    I DID see this Amiga get to the insert floppy screen once, then I bumped it, so I'm hoping a broken trace is the only issue.
    "Progress is being made if each mistake you make is a new one."

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    Hello,

    i do not know what you mean, but please, watch the picture:

    under U850 near BT176 there are three VIA that are the major cause of instability when an A4000D is affected by leakage of acid from BT176. Another issue can be the impossibility to use the full AGA chipset.


    Regards
    Stefano
    Attached Thumbnails Attached Thumbnails DCP_6620.jpg  

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