[Zig]

I am using a coupleof AMC be25A20 brushless servo amps.

They have a nice feature... apply the quadrature pulse trian and it will generate tacho signal internally to close the velocity loop.

MAJOR PROBLEM the tacho gain is set to 22KHz for 1 Volt output.

No way to change that on board. Worse still the goos people at AMC have scrubbed off IC labelsso hard to determine whihc chip(s) is used in the tacho circuit.

The machine generates a 7500KHz signal under conditions of normal operating speed.

Anybody out there with the knowledge of how to reduce the frequency for a decent signal output? Say 2 KHz/1volt!

[G59]

Can the velocity loop not be closed by supplying an analog 0-10v signal? Pump the the 7500khz into a DAC and feed the drive, voltage signal instead of pulses. I'm guessing this is for the spindle motor?

Worse still the goofs/ people at AMC have scrubbed off all IC labels so it's hard to determine which chip(s) are used in the tacho circuit.

I agree. But how else can they protect their intellectual property?

[Zig]

Two issues...

My apologies for the spelling mistake..it was not meant to read goos people..it was meant to say good people..which was then misinterpreted as goofs.. sincere apologies.

As for intellectual property.. i do not expect them to expose their art...just make it a bit more user friendly.. make it adjustable somehow.

Sadly the analogue input pin is setup for +/- 60V tacho input. Going from quadrature to proprietary analogue signal i would need to match it to the stated range. . Not so happy a solution.

[Zig]

Good news ...

I have implemented an external modification which has provided the requisite gain.

Machine operates quietly and precisely.

Following error is an order of magnitude lower.

All around a good result.

[iwaskevin]

zig how did You fix it ??

[Zig]

just as stated..external gain block in the feedback path...

Do you have a similar issue with Your equipment?