Need Help!- Boss 5 Loses Program & Zero Point

[timprebleco]

Guys,
Boss 5 Series I machine.
I have a problem with the program stopping sometimes, the axis just quit moving, the spindle continues to run though. It reestablishes the zero point at where it quits moving. The control read out shows zreo on the lines of program and zero on all the table and quill locations. The machine will run again as soon as you reset the zero points and reload the program. Then it will run through a couple of times and do it again. On a long program, 200 + lines it may stop on every other run.

[machintek]

What I have noticed is that occasionally one of these machines will reboot itself thus deleting the program and part program zero and TLOs. By the process of elimination, most of the time the culprit has been the 5 VDC zener diode in the white logic power supply.

George

[timprebleco]

George,
I will look in my owners manual tomorrow and see if I can figure out what part you are referring to.

[timprebleco]

George,
I am lost.
Last weekend I purchased another boss 5 for parts. I have the regulated power supply out of that machine in front of me. I have the drawing System wiring diagram for the power supply in front of me as well. On the drawing D9 between TP 7 (+5R) & TP 8 (GND) is probably the part I need to change. I have to be looking right at it, But I do not know what it looks like. I do not see anything that looks like a diode to me.
I have attached two pictures of the back side of the power supply, maybe this will help.

[machintek]

I cannot see the diodes in question. They are stud mounted devices. Meaning they have a bolt and nut on one end and a solder terminal on the other. It may take a 1/2 inch wrench to hold the hex on the diode. I remember seeing a picture of a row of these in the parts/electrical section of a old BOSS 5 or 6 manual. When I get to the office, I will look for it.

George

[timprebleco]

George,
Are they attached to the transfomer bracket or in a line below the transformer. The Picture in the book is Figure 13-4? It looks like the transformer has to be removed to get to them? The picture shows the area right below the transformer. Looks like there are 5 of them and two of something else.

[machintek]

Yes, those are diodes. Follow the wire numbers on the schematics to find the zener.

George