error message: "can't verify device number 1"

Thank you FVM for answering.

As I stated, I did replace the device on the PCB, and the new device programed a couple of times, then it did the same thing - "can't verify device number 1".

The number of times the new device was programed was 3 times, the third one did not work.

The power supply measures 3.44V (with a very good meter) and I also looked with a scope. The supply is clean.

The first device programed OK about 3 dozen times before the problem showed up. All that made me suspect a faulty printed board (broken trace, or what not).

I started building the second PCB, so far I have only the Altera soldered (including the 3.3V regulator, pins for the JTAG cable and various bypass caps). I just wanted to see if I can send the same *.pof file to another board. The result is positive, the new partialy built board is working.

So unless I can find the problem, I will have to finish a second prototype (200+ parts), and given a dealine (a show), I am less then thrilled.

I checked the JTAG connections many times (Ohm meter and scope) and they seem fine. I am starting to suspect some open power pin or ground pin somewhere. Some of those intermitent problems seem OK when you touch with a probe, then open up when you remove the probe.

The PCB is a multilayer board, and as a prototype, it gets flexed more then a final product. This is though to find, because some of the power and ground feedthrough are under the TQFP 144 pin Altera pakage.

I am speculating that the lack of varification, or any progarming related JTAG action requires only the 4 JTAG lines and power + ground to be connected, and all the other IO pins are "out of the way". Given that the IC has a lot of power and ground pins, I wonder if there is a specific pair (or pairs) of power and ground that are there for the JTAG, for a EPM1270T144.

Of course my thinking may be wrong. It may be that someting is "marginal", or intermitant. I have nothing to back it up. I have been around (63 years old), and it just "feels" like it.

Thanks again. I would appreciate your additional thoughts, and other Altera Gurus thoughts and sugestions regarding how to narrow it down.

Regards

Dan