ACT available

[Dreato]

I'm new to this forum. I found it a few weeks ago, and have since ordered several items from Bernhard at Panamatik. This post is for any new users, like me, to describe what I've learned. However, this is probably old news for forum veterans. Some of this summary is based on my personal experience, and some from reading this entire forum (that took 2 hours!).

1) If you're ordering from Bernhard at Panamatik, you'll send PayPal to him at Panamatik@vodafone.de. That's fone, not phone. F not PH. My Yankee mistake.

2) desoldering / removing chips - Paint a little flux on the old solder points. Use a spring loaded desoldering iron, and hold the tip flush against the board. Practice on some old boards you have lying around.

3) Low profile IC sockets are a necessity. ULTRA low profile! They're available on eBay. I bought 28 pin sockets, and cut them into 11 pin strips.

4) The HP27 calculator uses NMOS technology. There is no -12V power supplied from the power supply circuit. All the circuit diagrams you'll find are for the 21/22/25/29 series. This produces +6V, +4V and -12V.

5) Tanatalum capacitors, used in many HP calculators CAN go bad. I've found bad ones in the power supplies mentioned above, and also in HP 67 and 97. Persistent card reader errors (after mechanical rebuilding) in the 67 and 97 were solved with new tantalum caps.

5) Because of the differences in the HP27 power supply, Bernhard's ACT chip from the others in the 20 series will not work. You need to order the correct one from him, or modify the 25 ACT based on information in this thread.

7) Members of this forum, and throughout the site, are friendly and helpful. I've not seen snarky or rude comments about any questions or comments.

A new question: I ordered an HC67E ACT chip for my HP67 calculator. I'm interested especially in the Hex conversion and the stopwatch. I'm going to try this chip in my HP97. I would assume that different key codes will be necessary to access the extended functions. Does anyone know what these keycodes might be, or if they even exist?

Thanks and Best Regards,

Dave