Post Reply 
HP-21 - Crazy numbers
05-02-2019, 05:04 PM
Post: #9
RE: HP-21 - Crazy numbers
Hello Alberto,

in my case I didn't have an oscilloscope to check the signals. I only could see that reading cards wasn't a problem (after restoring the gummy wheel, of course), but recording wasn't possible.

I cleaned the cards with isopropyl alcohol, I inserted the cards as smooth as possible, etc. with no result.

I read that the calc needs more power recording than reading and that a fully charged battery pack is desirable to do this. So, I fully charged the batteries in an external charger (I use 3 Ni-MH AA) and I got then about 4.3V.

After 2-3 unsuccessful attempts of recording, it started then doing it properly. I suppose that the caps were reformed after some use.

Were you able to check the caps of the reader/writer amplifier?

Regards.

Oscar
Find all posts by this user
Quote this message in a reply
Post Reply 


Messages In This Thread
HP-21 - Crazy numbers - BusyCalc - 04-25-2019, 07:20 AM
RE: HP-21 - Crazy numbers - BusyCalc - 04-29-2019, 06:16 AM
RE: HP-21 - Crazy numbers - albertofenini - 05-02-2019, 02:05 PM
RE: HP-21 - Crazy numbers - BusyCalc - 05-02-2019, 08:56 AM
RE: HP-21 - Crazy numbers - BusyCalc - 05-02-2019, 01:49 PM
RE: HP-21 - Crazy numbers - BusyCalc - 05-02-2019 05:04 PM
RE: HP-21 - Crazy numbers - albertofenini - 05-02-2019, 05:09 PM
RE: HP-21 - Crazy numbers - BusyCalc - 05-04-2019, 09:38 PM



User(s) browsing this thread: 1 Guest(s)