[sportybob]

Hi Brian, The U18 chip is just below the round 14 pin connector opposit the side with the R15 adjustment pot. The U17 is located about dead cent on the board.

For the spindle speeds to change, the analog voltage needs to change.
One of a couple things have to happen due to;
1. . the programed spindle speed changes and it varies the analog voltage.
2. the spindle over ride switch changes and it varies the analog voltage.
3. the alalog voltage remains constant but the spindle drive changes the the spindle speed.

check the spindle drive display, it should read a frequency ( Hz) when it is running, check the analog voltage at the drive.( base line tests with your tach)
when the spindle speed changes:
1. check the spindle speed displayed % on the front panel , does it change? say from 100% to 50%. If yes then,This could be a override switch problem.
2. recheck the frequency and the analog voltage. Did either change? which one or both? Keep the rear door open on the machine so you have access to the drive with out shutting it down. If the analog increases / decreases and the drive freq goes up / down then the drive is doing what it is told. if the voltage remains constand with programed speed and just the freq changes then it would indicate a problem with the drive. If the analog is changeing up and or down Then we are back to the analog voltage being generated by the K/B encoder card.

The R15 gain pot is 100K ohm you could check the resistance across the pot ( base line) and then recheck when the spindle speed changes, This is harder to do because you need to have access to the backside of the card. You could try tapping on the side of the pot with yor fingernail and see if that has an effect. If the pot is changing values, replace the pot, if not then we are back to U18 as the most likly source of the problem.

One easy "try and see" would be to reformat the SRAM and reload the parameters, Back up you programs if needed. This is easy and takes 2-3 mins. as long as you have a back up parameter disk.


As mentioned earlier, to use the "new" control/acro card the control would need to be modified to a "-B" This requires an internal wireing changes to the interface FPP connector and a new internal cable(s) as well as a new external 9512-x cable. PM me if this is the route you want to take.
PM me for my #
Sportybob

[Brian L]

1. The spindle speed on the display is always what is commanded, if I have called 1500 it reads 1500, whether the spindle is really running 750, 1500, or 3000.
2. Frequency and analog voltage jive exactly with whatever rpm the machine is running, regardless of what is/was commanded, if I'm running 1500 I have 3V, 3000 I have 6V, the VFD is behaving correctly.

I'm hoping this is a result of bad chips at U18 and/or U17 and I can replace chips rather than change out all sorts of stuff.