I have had it for a couple of years, and it's a long time I'd use it. When I recently bought it, I wrote a couple of 27c256 and worked perfectly. Now I wanted to write some 27c256 and I can't even read them. In the buffer section all is 00.
I have checked in the Test H/W section Vcc (4.65V) and Vpp (12.47V). Also tried to read some 27c512 and the same thing.
Couldn't find a similar problem in the forum and thats why I'm posting. Hope someone can help me.
I have the same problem with my 27C256B. I read it just fine, the software says the EPROM is okay and everything is good, yet I get all 00 in the buffer. Did you ever manage to resolve this?
Your programmer isn't suitable for programming any EPROMs. VCC needs to be 6.0-6.25V to program any EPROM larger than 32Kb. That programmer has several design flaws. You can read about them at http://www.willem.org/cgi-bin/yabb22/YaBB.pl?num=1145286403
Your programmer will draw about 300mA from the USB port and can damage your port. The programmer isn't USB compliant and should only draw 100mA max from the port. I thought it was the step-up regulator that was the problem, but PCB3 designs don't draw excessive current; so it's something specific to the enhanced universal design.
USB power shouldn't be used for programming EPROMs anyway...
Problems reading and writing with 27C256/27C512
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Posted - 05/21/2008 : 18:52:21
