PMEL Forum

I HAVE BEEN WORKING ON A 1127-2 MAIN PCB  AND CANT FIGURE OUT WHY MY 100PSI RANGE CANT BE ALIGNED.  THE SIGNAL COMING FORM THE BAROCEL IS OKAY, BUT ONCE IT GET TO THE OUTPUT AMPLIFIER CIRCUIT MY OUT PUT VOLTAGE GOES SIX MILLI VOLTS HIGHER THEN IT SHOULD BE.  I TRIED REPLACING THE AMPLIFIER BUT STILL DOESN'T WORK. 

What are you measuring your output voltage with?

This is not my expertise, but I have seen failures like this caused by a false assumption of that 6mv....Is it really 6mv? If you have a calibrated HP 34401 meter on the lowest dc voltage range, or a 3458A would be even better, would these meters repeat the 6mv measurement?

What makes you certain about that voltage measurement?

Now lets talk about that 100PSI...what are you measuring this with?

FOR THE PRESSURE STANDARD I AM USING A KING NUTRONICS 3689A AND TO MEASURE MY VOLTAGE I AM USING AN HP3458A. 

Quote from: ADATECH on 12-21-2010 -- 17:09:47
I HAVE BEEN WORKING ON A 1127-2 MAIN PCB  AND CANT FIGURE OUT WHY MY 100PSI RANGE CANT BE ALIGNED.  THE SIGNAL COMING FORM THE BAROCEL IS OKAY, BUT ONCE IT GET TO THE OUTPUT AMPLIFIER CIRCUIT MY OUT PUT VOLTAGE GOES SIX MILLI VOLTS HIGHER THEN IT SHOULD BE.  I TRIED REPLACING THE AMPLIFIER BUT STILL DOESN'T WORK.

I know this is way late, but you have a bad range selector switch, or the 100psi variable doesn't have enough range.

I'm amazed those things are still in use!  :-o