Multiplex trouble shooting

I guess I need to post something on topic for the group. Last week I was working on a Mazak Multiplex that lost the ability to
index the turret. It is always fun doing a multishift repair since two of our shifts don't write a freeking thing down to give you an idea of what was tested and what was learned. It seems you work 4 hrs go get back to where things were when you left the previous day.
Anyway, the first night I worked on it, I noticed the turret clamp/unclamp switch wasn't going off when unclamped. Wasn't all that worried because we hadn't got that far.
The mill/turret motor just wanted to spin and give an error I forget now.
In the morning I passed down the info I had learned and we talked a bit the day tech mentioned that mazak said that shifter has to shift to turret side before unclamp. From that we figured that Mill/Turret motor orients and is under control to hold position, The shifter system moves from mill side from turret side and meshes gear, then the turret can unclamp since servo is going to hold it. Then motor spins turret to proper position, clamp, yada.
Well a day goes by since we don't have the motor and then the next day we have one. We evidently had a motor and didn't know it. Inventory is a serious issue where I work. It isn't walking off, we just can't track it.
The prior shift tells us the motor is in but the valve that shifts is bad. That made no sense since we checked that out earlier.
Oh well, pull up diagnosis screen look at bits, Shifter output doesn't match position prox inputs. Find out someone swaped sides on shifter valve.
Once again we try to index turret. No go. 239 and 330 condition 4. Chit. Looking at bits, I find that the pneumatic coupler that connects to live tools does not show retracted. Folowing wiring, we find that someone improvised a connector and it wasn't making contact. A little crimping fixed that.
Try again, get an alarm about turret clamping. Hey no chit, I was hoping to get there. That one was expected. Crawl in back, screw prox out a turn, guess it got more sensitive since the rod and disk are moving the proper amount.
Try again, index's fine.
Now if I can figure out the taper problem on the GI-20 grinder this machine feeds I will be very happy. One of those deals where the machine you fix isn't all that useful if the machine it feeds is down also.
Wes S
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Wes, Tell me something, does this multishift troubleshooting actually WORK? I think I'd go nuts if I was trying to troubleshoot something and every time I come back to the task someone else has made changes! The first rule of effective trouble shooting is try ONE thing at a time, and put it back the way it was if it didn't help. It sounds to me like you guys break all the rules and it actually takes much longer than if you just assigned the task to one guy and the machine stays down until he returns the next day.
I once sold 15 machines to a customer. He calls me a short time later and says 14 out of 15 are no longer working despite their maintenance peoples best efforts. I go out there with one set of known good replacement parts. After one day I have 14 out of fifteen running! I found a total of 4 different bad parts and two failures of the same part, otherwise I'd have gotten them all running. They essentially just swapped parts and slowly lost track of which parts were actually bad.
Gary H. Lucas
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I don't think multi shift troubleshooting works at all. Much like the strange concept that if you need the job done twice as fast put twice as many people on it.
I would love to come in and read a decent pass down on earlier efforts. The only good one I tend to find is mine from the previous night.

Don't get me going on board swappers. I worked the bugs out of few test cells and marked easily removed components with the cell number. Fast forward a month or so. Nothing is where it started at. All of the items have individual calibration requirements.
While board swapping may have to be resorted to in testing you mark the board to make sure you don't lose track and you return the board if it didn't fix problem to donor machine immediately and then make sure donor is still functioning.
Wes S
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snipped-for-privacy@lycos.com wrote:

The best way if you are working shifts is to arrange to talk to the guys on the previous shift rather than leaving criptic notes.
Get to bad boards or two separate problems going in a machine and you had better know your stuff.
I had that probem several weeks ago with an old GE 1050. Sent the boards out to CA to get em sorted out. Warren (UEI) sorted things out. Two bad boards and the tape reader was hit and miss. The spare board I had was also bad.
John

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