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HP48GX : faulty Port 2 ? any way to repair it ?
Message #1 Posted by Antoine M. CouŽtte on 12 Jan 2012, 2:59 a.m.

Hello to all,

In the past few weeks, I have observed the following symptoms on an HP48GX which I have extensively used to develop my HP41 ASTRONAV Software through HrastProgrammer HP41X/Y/Z Emulator.

Whenever I plug into port 2 any type of Card (ROM Card or RAM MEMORY Cards), I get the following message "Warning INVALID CARD DATA".

In addition to this, whenever I plug into Port 2 a RAM Memory card 256K or bigger, all Ports from :2: to ... :33: show as being physically residing within the system, although for a 2MB Ramcard for example, no such Ports above :17: physically exist in the Calculator.

Trying to "PINIT", or even trying "Hard reset" through inserting a needle into the appropriate "foot hole" does not solve this situation at all.

Any clue here ? any (simple) way to fix it ?

Thanks for any information and/or help here.

Antoine

Antoine M. "Kermit" CouŽtte

      
Re: HP48GX : faulty Port 2 ? any way to repair it ?
Message #2 Posted by Raymond Del Tondo on 12 Jan 2012, 3:56 a.m.,
in response to message #1 by Antoine M. CouŽtte

Hello,

the papaer clip reset does not automatically reset all memory,
it's just a hardware reset for the CPU.

Given the symptoms of your calc, you should unplug all cards,
remove the card batteries, and initiate a cold start (ON+A+F) .
After that, and _before_ loading any 3rd party software,
you can insert a ROM card, and check if the symptom is still existent.

HTH

Ray

            
Re: HP48GX : faulty Port 2 ? any way to repair it ?
Message #3 Posted by Antoine M. CouŽtte on 12 Jan 2012, 9:11 a.m.,
in response to message #2 by Raymond Del Tondo

Thank you Raymond for your kind advice.

I followed it and proceeded as you indicated. I could not establish again a normal calculator behavior since it did not change anything from the previous state depicted here-above.

Is it a software or rather a hardware problem ?

Antoine

      
Re: HP48GX : faulty Port 2 ? any way to repair it ?
Message #4 Posted by Lyuka on 12 Jan 2012, 7:16 p.m.,
in response to message #1 by Antoine M. CouŽtte

Hi Antoine,

Quote:
In addition to this, whenever I plug into Port 2 a RAM Memory card 256K or bigger, all Ports from :2: to ... :33: show as being physically residing within the system, although for a 2MB Ramcard for example, no such Ports above :17: physically exist in the Calculator.

The symptoms you stated above implies bridged contacts at the card slot or the malfunctioning address decoder i.e. dead 74HC174 chip on the mother board which is used to make signals to select memory chip in the card.

Try cleaning the contacts of the card slot using compressed air to remove contamination which might exists.

Good luck.

Regards,
Lyuka

            
Re: HP48GX : faulty Port 2 ? any way to repair it ?
Message #5 Posted by Antoine M. CouŽtte on 13 Jan 2012, 10:56 p.m.,
in response to message #4 by Lyuka

Dear Lyuka,

Thank you for your information and advice.

I did blow compressed air on the card slots contacts to remove possible contamination. The symptoms remain unchanged, and I would conclude that there is something wrong with the address decoder, which is a gripe totally beyond my nonexistent repair capabilities.

In the (dubious ?) case when repairing might be an option, is it worth getting this HP48GX fixed ?

Thank you again, Lyuka San, and

Best Regards

Antoine

Antoine M. CouŽtte


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