HP 29 & 21

[zixingcheche]

(11-13-2022 04:32 AM)rprosperi Wrote:  It will work if the ACT is the only bad component and there is not other damage. The 29C also has RAM chips (21 has no separate RAM chips), which could also be bad, and it's possible other components on the board have been damaged.

Did an old battery leak acid residue into the 29C? Do you see any evidence of blue/green residue on the board or on any components? If you can see ANY residue then the entire board must be cleaned to remove, which can be difficult as the green gunk often seeps under chips may have done damage, even if the surface of the PCB and components look clean. Check carefully and remove any residue that you can see with Q-tips soaked in vinegar.

Just to be sure you know, NEVER plug HP's power adapter into any 29C, doing this is what kills the ACT and possibly other components. Either use Alkaline cells, or charge NiCD or NiMH cells in an external smart charger.

Thank you so much for your kindly comments & advices. I’ll try to clean the pcb first, and then try to exchange the ACT chip.
Thanks!