Running at low voltage

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Running at low voltage

Postby Charly » Aug Mon 13, 2007 2:58 am

Hi together,
I sent a text this weekend but something happend lo let it disappear.
So I ask again:
My Micro- KIM has a funny effect:
When my external power-supply is switched to 6V - voltage on board about 4.5V - everything works fine.
When I increase voltage to 7.5 V input - voltage on board 5.0 V - my KIM starts but hitting any key on the keypad or on computer in terminal mode it locks up. After pressing reset it starts again until I decrease the input voltage.
I changed CPU, RIOT and RAM - same effect! When using a CMOS 65c02 any keypress under full voltage leads to display "0000 00".
Any ideas? As you can imagine, I could live with this effect. But I'm a perfectionist....
Thanks in advantage
Charly
Sorry for my english - I left school many years ago...
Charly
 
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Postby vbriel » Aug Mon 13, 2007 6:22 am

I would think this is an EPROM issue. That is the one item you haven't replaced. Do you have access to an EPROM and a programmer? The source code bin file is on the Micro-KIM page for download.

Vince
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Eprom...

Postby Charly » Aug Mon 13, 2007 6:42 am

vbriel wrote:I would think this is an EPROM issue. That is the one item you haven't replaced. Do you have access to an EPROM and a programmer? The source code bin file is on the Micro-KIM page for download.

Vince


Thanks a lot, Vince. That is exactly what I thought. I had a similar effect with my old PET. OK I'll program another EPROM - no problem at all.
Charly
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Postby mike3 » Aug Mon 13, 2007 12:42 pm

are you using one of the wall wort switchable supplies? ...correct me if am wrong but dosn't the current decrease as the voltage increases on some of these
>>>>>>>>Mike
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Problem solved!

Postby Charly » Aug Tue 14, 2007 5:22 am

Hi together,
another good news: My Micro-Kim is running ok now. The EPROM had "weak cells". I programmed another and - BINGO! "Number five is living" (I got serial number 000005)
Thanks a lot for help.
Charly DL4DBY
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