Extension board utracer6 issue

[Leonard Bocioc]

Hello members,

my name is Leonard, i just built the utracer6 with extension board.

The calibration of the main board was successful.

In the process of calibrationg the extension board, i am failing at step one getting this graph:

 

What am i missing?

Thanks for your input.

[Never Mind]

Leonard

A few suggestions to provide hints as to the possible trouble.

1) Is the PIC firmware the revision that supports the extension board?

2) Did you recheck that the jumpers 1,2,3 are all in the correct position?

3) Are you sure your connections and the correct resistor value are as in step 1.2

4) Did step 1.5, setting the voltage to zero at R8 work for you?

5) Your curve shows the uTracer6 is measuring maximum grid current (AD clipping) for all grid voltages.

So ...

A) The output of the positive grid circuit is shorted to the cathode in some way (seems unlikely but possible) and so supplying a lot of current.

B) IC2-A1, output is stuck at a high voltage level. Measure the voltage at IC A1/R3, you should get very close to zero volts when the utracer6 is at rest.

If not zero volts at IC2-A1output triple check the circuits for shorts and resistor value errors around IC2-A1. If there were and "probe slips" IC2 could have been damaged.

C) D5 the BAT74 was installed backwards or is shorted and pulling the output of IC2-A1 high to the 5V rail.

Good luck

Bob

[Never Mind]

Leonard

One more 

R6 the 4.7 ohm resistor is missing or a high value.

Bob

[Leonard Bocioc]

Well, big thanks to you for pointing me in the right direction.

All i can say is: 4.7K is not 4.7ohm.

Stupid me.

[Never Mind]

Leonard

Great to hear you found it and happy I was of some help.

Bob