A4000 re-repair

[anightin]

Dear All,

I hope you are well, I am new to this forum and it's my first post

I acquired an A4000 last year and the machine has been working well. However recently it has been losing it's time and date (U177?/U178?) and just this week it stopped registering fast RAM -- a quick hack with DiagROM revealed that the bottom 8 bytes is stuck at FF (U891?)

I knew the machine had previously been patched up -- apparently by someone in the Netherlands?

I am in the process of re-reparing the repair and have just started to take a look. First job was to take off some prime suspect components and give the board a bath in distilled vinegar and a rinse in IPA.

It's showing some patch wires touching the pads. What is the recommended best way of placing my replacement IC's?

Re-solder the patch wires to the pads, pop the IC on top and re-flow hoping the patch wire stays put?

Many thanks

[anightin]

Thanks for the comments 

I have replaced U891 and U177 with new parts (Mouser) and have added a new RTC IC (AmigaKit).

The machine powers up from cold, remembers the time and date, and detects FASTRAM, however when warm (5-10mins) it starts misreading the bottom byte as above  .

I am now down to having only 1 bit stuck in the lowest byte which I think is bit 5 of 8.

Investigation continues... I am hoping it is a bad joint/patch wire as the ICs are new...


 

[anightin]

Wow that was an epic battle