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jpod1977
9 Posts |
 Posted - 07/21/2005 : 06:50:46
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 Having a problem writing 27c512, 27c256,27256,27512,27c64 I am able to read these chips (i think, Dont now If it is correct or not)
not able to writ anything to them tried to chane just 1 byte gives me errors after it programs the chip (on verify)at the address i changed,
tried on three different computers no luck same thing or it writes garbage (It was writing 10hex at random address)
one chip i was able to write to all 00's would not let me write to it again when ever i trie to rewrite that chip the Vpp light comes on and then shut off right away (shorted!?)
any way tried on two xp machines one SP1 the other SP2
and one ME machine
port setting on all machines are epp+ecp tried epp and ecp alone also
on the xp machines i also installed the io drivers
voltage at pins
1 vpp on 12.84
2 - 15 4.39 v
17 - 21 4.39
22 3.78
23 4.39
24 12.84
25 4.39
26 2.95
27 - 29 4.39
30 4.98
31 0.00<---dont know why this is at 0
32 4.98
 is there any thing else to test??
what could i be doing wrong??
Thank you in advance
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Edited by - jpod1977 on 07/21/2005 07:23:35
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| Reply #1
jpod1977
9 Posts |
Posted - 07/21/2005 : 06:56:52
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dip sw 3,5,7,8,9,on rest off program is set to pcb3
and its a dual power willem
sorry that migght help
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| Reply #2
jpod1977
9 Posts |
Posted - 07/21/2005 : 07:18:31
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reset dip sw for hardware test and retested voltage on zif pins
1 12.84
2 - 15 4.39
17 - 21 4.39
22 3.78
23 4.38
24,25 4.39
26 2.95
27 - 31 4.39
32 4.99
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Edited by - jpod1977 on 07/21/2005 07:19:11 |
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| Reply #3
jpod1977
9 Posts |
Posted - 07/21/2005 : 09:02:01
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| ok i think i know what is wrong these chips (27cXXX and 27XXX) are EPROMS not EEPROMs. I think i need a UV Lamp to erase them frist. If so where can i get one (or will Blacklight tube work if so how long do they need to be under it) |
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| Reply #4
tulufan
28 Posts |
Posted - 07/21/2005 : 10:31:08
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Yah. The 27CXXX and 27XXX EPROM need the UV light to erase the content before write it.
There are lot of them listed in eBay(I think you do not want the expansive one from the distributor. such as www.digikey.com) |
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| Reply #5
jpod1977
9 Posts |
Posted - 07/21/2005 : 14:07:39
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well going to have to get on the blacklight did not work even sitting underit for 5 hours
thanks for the help
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| Reply #6
tulufan
28 Posts |
Posted - 07/21/2005 : 17:53:13
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You have to use the UV eraser.
You may need sit under the sun light for a month to erase the EPROM . The regular black light does not work either. |
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| Reply #7
firyembers
United Kingdom
4 Posts |
Posted - 10/19/2005 : 08:51:27
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This semms to be the place to get one,it's the cheapest i have seen so far.
http://anyway.no-ip.org:8080/
and they accept PayPal. |
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Topic |
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Problem writing 27c512
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