VP-20 improvement
From a very alert visitor of this site (Knutsel), I got this message, telling me that there is still room for improvement to the " build it yourself " version of the VP-20/DL-20 programmer as described on the previous page.
The guy that sells these kits (Willem) tells me that it's just a matter of not reading carefully enough. The schematics clearly show a 0K description, but apparently some people read that as 10K.
Anyhow, down here you will find an explanation of the adjustments and the reason why:
Do you often receive error messages when programming the Eeprom on your card?? For instance Loader doesn't work (ChipCat) or. ... failed at address 0000 (ICprog)?? Well, there might be a very simple cure: a wire-bridge.
On the VP-20/DL-20 print-circuit, usually a 10 K-Ohm resistor is used, whereas a solid wire would be much more effective. In the drawing down here you can see the resistor marked in red. So just bridge that resistor with a solid wire and your problems might be over completely.
In the download section you can download a larger drawing for a better view of all the details.
The download file is called Vp20verbeterd.zip and is 30 Kb in size.
But you can also download this zip file by clicking on the drawing above,
Mind you: I have never experienced any problems with my DL-20, so I assume that not all programmers would need (or even benefit) from such a modification. But if you are experiencing problems with your programmer, just have a go with this solution from Knutsel.
Thanks Knutsel and Willem.