HP 45 input voltage requirements



#4

I have been asked to trouble shoot my friends HP 45, because I have a lot of calculators myself. I don't have much electronic expertise or tools.

The calculator worked for years, operated on the AC adaptor with no battery pack installed. It has quit working, and I thought I might figure out if it would work on batteries alone, by connecting some to approximate the original battery pack. If it worked, then I'd know the adaptor wasn't. The battery contacts don't seem to be marked with regard to polarity. The adaptor does have an input voltage switch and is rated at 0.8W (I think, it is not with me at this moment).

Any suggestions are appreciated.

TIA

Bill


#5

Hi Bill. The ac adapter for the classic series (35,45,65,67,etc) actually puts out two DC signals: a 5.4 v signal to power the machine, and a constant current signal (which will read about 16vdc with no load) to charge the battery pack. This of course means that the AC adaptor contains rectifier circuitry. I've heard that the smoothing capacitors in the rectifier can go out which results in excessive ripple voltage, which can cause erratic operation of the calculator.

The bottom battery contact is positive one. Note that you'll need to have the adaptor disconnected from the calc to power it from the battery contacts. Also be sure that those little spring loaded plates in the adapter recepticle are making contact with the two outside pins, shorting them together (this is how battery power is routed to the calculator when the adapter is not connected).

Hopefully it's just a bad adapter...
Best regards, Hal


#6

Hopefully this is just the information I need to find that the 45 itself is OK. Thank you very much.

Bill


Possibly Related Threads...
Thread Author Replies Views Last Post
  INPUT for HP Prime Eddie W. Shore 3 253 11-17-2013, 04:46 PM
Last Post: Michael de Estrada
  HP Prime Tutorial #4 is up (CASE/CHOOSE/INPUT) Eddie W. Shore 1 221 11-15-2013, 07:32 AM
Last Post: Davi Ribeiro de Oliveira
  HP Prime Programming Tutorial #3: WHILE, INPUT, KILL, REPEAT, GETKEY Eddie W. Shore 5 383 11-07-2013, 12:25 AM
Last Post: Han
  minor visual bug in INPUT Han 0 128 10-03-2013, 01:13 PM
Last Post: Han
  Input syntax on the Prime Gilles Carpentier 6 335 08-23-2013, 04:31 AM
Last Post: Gilles Carpentier
  Input CAS var on HP Prime Mic 2 181 08-22-2013, 02:29 PM
Last Post: Mic
  HP 85 Serial Interface; INPUT Example? inaki 1 199 06-12-2013, 11:09 PM
Last Post: Paul Berger (Canada)
  HP33E how to input numbers RalfGeiger 6 310 05-07-2013, 02:41 PM
Last Post: Ron Ross
  HP 35s - multiple program input values? Arno 3 269 04-29-2013, 11:27 AM
Last Post: Gerson W. Barbosa
  Repair HP 45 Nanoman 3 200 04-12-2013, 05:40 PM
Last Post: BobVA

Forum Jump: