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Sinumerik 3M saga, Time for TNC 320?

tomp

Cast Iron
Joined
Feb 27, 2003
Location
austin tx
Hi folks,

Have posted here in quite a while but this week 3M gremlins struck full force on the Deckel FP3NC
and Im looking for advice/ideas on how to proceed.

Here is the run down for the last 2 weeks.

1) position readout for all axis stopped working. Just zeros even when rotating an axis with wrench.
Tracked that down to failed 74sn244 driver chip. Fixed it. Yeah. (glad I kept a stash of ttl! )

2) Ran machine for one day and power supply quit. Debugged it. The thermal temp switch has high
18 ohm resistance. Should be near short. Replaced it. Works!

3) Ran for another day. Y-axis clamping errors started. Tracked it down to a bad 3325 board (I think)
thats outputting higher value than other axis. Cannot compensate with tach.

4) While debugging this the PLC stopped! Now it wont stay running for more than an hour or so!

All this in just two weeks!!! Not heat related. Its been 65 in the shop for a while now and inside cabinet fans working and surfaces barely warm.

To fix this the 3325 command board and the PLC unit is needed and its just a matter of time before the next failure I fear.

What are the refit options (unless a bargain on 3M spare parts turns up).

The Heidenhain TNC 320 looks interesting but no idea what they cost.

(BTW, replaced the Bosch amp last year with AMC units. Should have done that long ago. So quiet!)

-Tom
 
Hello,

could you elaborate on the AMC units you installed. I've not heard of this.

Just for you as an option for consideration, I have a complete 3M control for sale (the control box with all the cards residing in the control cabinet).

Martin
 
Hi Martin, might be interested in your 3m box and give this thing one more round. Shoot me a PM.

The AMC amps I used are BE25A20 that can do brushed or brushless duty. There are new AMC amps that are a lot more capable but these do the job and can be found on EB for low cost. Ill attach a couple of photos when I figure out how to upload them. If your interested Ill did up my wiring sketch. The FAULT indicator on AMC sets fault when the AMC is not enabled. Bosch only sets it when there is an actual fault. I used relay logic to handle that. Probably should have just used a ttl chip.

BTW, I have a bunch of Bosh servo boards for parts. mostly in various states of broken.

-TomPIMG2.jpgIMG1.jpg
 
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Update, replaced the PLC unit and swapped eprom modules. After PLC reset the green light and single led on 3840 card are on but I cannot get any display or buttons working.

Ive tried the cancel 2 ,3 and 4 followed by input 8 with a reset in between each. This has worked in the past but not this time. I suspect there may still be a hardware issue but not sure how to proceed.

Anyone with some debugging suggestions?

-Tom P.
 
UPDATE: Persistence paid off but it was a fight. Here is the list of problems
that had to be dealt with:

1) Obtain a new PLC and swapped in the ram modules. After the PLC reset
I have the one red led on 3840 and single green on plc but:

2) No display! Turns out the 3325 command board was doing something nasty to
the NC section which runs the display. I swapped the 3325 with another and
the display returned!

3) After control reload it will not power up servo amps. This turned out to be a
problem with the INPUT board bringing in the SERVO AMP ready signal. Why would
that fail now?

4) And don't forget the original position board failure.

The good news is these boards are common enough they usually turn up sooner or later. The bad news is
they are all pretty old now.

-Tom P.
 








 
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