[copper460]

Hi All,

I purchased a Takisawa TP-3 Lathe knowing that it had some issues. One alarm pops up on the X axis. The machine will home fine, but after moving the axis it will not go home again without an over travel alarm. But the limit switches are not even being touched. Until I turn off and on the machine I cannot reference return. Also have to do P + Cancel on startup. I decided to check the pulse coder on the x axis. The machine is coated in oil, so I thought something might be up. Long story short, it looked good. Someone had been in there before though.

Put everything together again and for the first time the machine ran a program with no errors. Not even an axis error on start up. Homing was no problem. Later on my bench I see a little piece of electronics. Exhibit A. NEC diode (I believe) Then checked the pulse coder PCB. Exhibit B. Position C1 At the top you can see something obviously broke off. My quandary is...the machine is now running...but its technically broke...do I fix it? I'm not sure of the function of that particular piece of the PCB. My only concern is that could it lead to a crash? My experience with alarms is, that the machine stops. It really seems that either the diode(?) was bad or broken somehow and shorting out. Why else would the alarms stop.

Any thoughts? Thank you for your help.

[Jim Dawson]

That is a capacitor. The clues are the ''20V'' (20 volt) on the case, the ''C1'' on the board, and the ''+'' next to the ''NEC'' 6.8 MicroFarad maybe?

Based on it's position on the board, best guess is that it is a filter capacitor for the 5V input.

[copper460]

Thank you Jim. I appreciate the feedback.

Nice to meet another Oregonian and have some overlapping interests. We're in the Timber industry.

[CitizenOfDreams]

Let me play Sherlock Holmes.

Here is what might have happened: the capacitor was partially broken off and it made intermittent contact as the axis was moving. That generated electrical noise on the +5V bus, messing up the encoder. Breaking the capacitor off fixed that problem.

Without the capacitor, the encoder might be more sensitive to noise and may give you occasional errors. Or it might work just fine as it is.

Installing a new capacitor is pretty easy if you are good with a soldering iron. If you are not, better ask someone who is.

[copper460]

Thank you CitizenOfDreams. I'm going to run it and see what happens. If it acts up, I'll definitely solder a new capacitor.

[Jim Dawson]

Thank you Jim. I appreciate the feedback.

Nice to meet another Oregonian and have some overlapping interests. We're in the Timber industry.

My pleasure.

I spent many years in and around the wood products industry. Mostly automating sawmills.

Where are you located?