On Tue, 18 Dec 2018 09:16:36 -0800,
et...@whidbey.com wrote:
> I have a CNC machine with a FANUC control. The control uses what
>the web calls "hybrid ICs". It looks like these devices consist of
>some sort of IC and/or others ICs and pasive devices.
Yep. A local machine shop had a Mori Seiki 5 axis mill with a Fanuc
controller. Lousy photo at top of:
<
http://www.santacruzprecision.com/equipment.htm>
I was the unofficial repairman. The owner of the shop sold it about 3
years ago and retired. He's still around, but all the Fanuc paperwork
and spare boards went to the buyers.
I also used to design and make hybrid electronics in the late 1960's
for Alpha Electronics, a manufacturer of 2-way radio accessories. The
hybrids were used in CTCSS encoder/decoder boards and in early LED
digital watches. Under the hybrid is essentially a custom "circuit
board" build on an alumina ceramic substrate, with conductive traces
and resistors silk screened and baked onto the substrate. All of them
were custom made for some specific purpose, which makes them very
difficult to source should the supply dry up. For example, the
HP8640B RF signal generator has a hybrid RF power amp output stage
that tends to self destruct. HP no longer makes or sells them, so
creative repairs and replacements are epidemic.
<
https://www.ve7ca.net/TstH86.htm#HK14>
You're probably going to be faced with a similar problem. It might be
possible to replace a hybrid with a work alike device on a PCB, but
then you would need a schematic of the hybrid internals, which you
probably don't have and is probably difficult to find. Here's one
attempt to reverse engineer the HP8640B hybrid:
<
https://www.ve7ca.net/TST/H86/hybrid.png>
Not the lack of detail, such as xsistor part numbers.
> The control is old enough that getting new boards is kind of a crap
>shoot. And I have replaced bad boards with good used boards only to
>have them fail sometime later. I want to have a stock of known good
>boards.
> So I need to test the boards but I don't really have the expertise.
>I'll need to figure it out as I go. One thing that might help is to
>find out what is under the epoxy or whatever is covering the devices
>on the hybrid ICs.
I did some of that many years ago. Similar problem, but no hybrids or
exotic parts. I ended up building a test fixture with a spring pins
at all key test points. The fixture simulated the operation of the
machine, which was a controller for an old rotary blade lumber mill.
You could do the same with the Fanuc controller boards, except I seem
to recall that there were about 8 boards in the controller cage, which
would turn this into a major project. I only had to make one fixture.
> These are parts from the 1980s. Can the coating be removed without
>damaging whatever is underneath? Is it likely the devices on the
>hybrid board will be identifiable once exposed?
No and no. You could probably soften the coating, but if you try to
pull on it, it will tear apart the wire bonds even if the transistors
and IC's are coated with junction compound.
> I have looked for datasheets and pinouts on the hybrids but no luck
>yet. Maybe I need to look harder.
Have you considered removing all the Fanuc stuff and replacing it with
a more modern CNC controller and motor control? I did that a few
months ago on a Shizuoka vertical mill replace an aging Bandit
controller:
<
http://www.learnbydestroying.com/jeffl/pics/CNC-conversion/index.html>
Total cost of the 3 servos, 3 motor drivers, controller, and a mess of
incidentals was about $2,000. The choice was to try to keep the
Bandit alive a little longer, or to rip it out and start over.
Starting over turned out to be better, easier and cheaper.
However, if you want to continue to do battle with the Fanuc
controller, you might check on the Fanuc forum on CNCzone:
<
https://www.cnczone.com/forums/fanuc/>
Hint: If really you want help with something, it's usually helpful to
provide the model number of the machine and controller.
--
Jeff Liebermann
je...@cruzio.com
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS
831-336-2558