Interesting troubleshooting RE: Heidenhain TNC310

[gus]

Thought some would find it interesting my conclusions on my retrofitted TNC 310 that I have had a problem with.

Machine is a BTC that I kept much of the original power circuits but none of the control and do not use the toolchanger.

I had a control failure a few years ago most likely due to the 24v supply going south and frying the control[it operated on 24v]

A few months ago it started exhibiting similar symptoms to its previous failure, dying with a flashing error, buffer dump to screen only under spindle load, usually related to chatter at the tool, but now just as soon as the spindle had to take any load at all.
Called heidenhain to ask about the specific error message, they confirmed most likely noise in the 24v
Checked out both 24v supplies with a scope, but found nothing conclusive

It had taken a few months for me to get to it, as this is now a 3rd string machine, although it was my number one for several years. I ran it with no part, fine. Put a part in, boom , after 10 seconds of cutting it dies.

Now a freq drive failure will not cause a emo, or a random error, so the freq drive[hitachi] seems fine.

I scratch my head and play with a few things, re ground one of the power supplies, try running another part, but I don't feel like getting everything wet[scope is nearby] so I turn the coolant pump off and just drip some coolant on the part[hey, its gonna die in a second anyway]

Runs all the way through.

Twice

Turn on the pump, bang, kicks out was soon as it takes a chip.


pump off, runs a third time.

Now the pump is audibly noisy, 30 years old and slow to build pressure, but once it is running it has always been fine.

I buy a $100 pump from MSC, wire it up, machine runs all day long, not a peep.


here is the theory to explain my observations:

Pump is not only audibly noisy, but electrically noisy, it takes its 3 phase from maybe 12 wire inches away from the spindle power take off. It is throwing noise into the 3 phase which is what the freq drive uses for all its logic power and current. The freq drive can reject it when it is not under load,. but as soon as it starts to try and maintain under load it starts making high frequency noise back into the +- 10 volts into the control, or perhaps power spikes tall enough to get through the 24v supply filtering, bingo game over.

Now, I don't care enough to try and torture my control and find out what theory is true, but it works now, and that is what counts.


I thought it would be an interesting story to throw out so when some one here encourages a newbie to check everything, tell us everything, they will know why.

[RMARCH]

Thanks Gus !!! That is Very interesting.

[Dirky]

OH.....come on Gus......I coulda told you it was the noisy pump.....I new it all along........Tee hee hee ... ;-)