HP 25C troubleshooting

[rprosperi]

Though Steve's recommended solution is far better, and I also strongly recommend it (or even better, Panamatik's Woodstock Low-Power), for the record there is also an option of replacing the bad ACT chip with another from a working machine, which can be taken from any Woodstock including the HP-21 which is more available and typically cheaper to purchase. Though I generally avoid recommending destroying a working vintage machine, sacrificing a 21 to restore a 25 can be justified IMHO.

But I too say you should go with Panamatik's kit, it provides you with a much better machine, and no Woodstock would be harmed in the process.