boss 5 finally powered up, some issues

[CincyTJ]

I finally got my power cart and RPC hooked to the series 1 boss 5 and there are some issues. x and y movement is great but it looks like the z-axis stepper is bad. when I try to jog or step it just vibrates back and forth. also the z limit switches are bypassed and one is cracked in half. and worst of all, when I started the spindle itmakes a nasty clatter. I can turn the spindle about 5 degrees back and forth like backlash. I can hear it hitting hard up inside the top at each side of the rotation. please tell me this is simply a sheared key a picture of the switch layout on thez axis would be good too

thanx

[machintek]

Hard hit is slop in drive plus worn out vari drive bushings. Prior owner did not keep up with the machine maintenance.
Z axis up top has 2 switches. A deceleration switch and a home/stop switch.
May also have blown Z axis final drive transistor(s).

George

[CincyTJ]

Originally Posted by machintek Hard hit is slop in drive plus worn out vari drive bushings. Prior owner did not keep up with the machine maintenance. Z axis up top has 2 switches. A deceleration switch and a home/stop switch. May also have blown Z axis final drive transistor(s). George

Are the worn out bushing part of a drive rebuild kit? I found a kit to rebuild the drive for around $250? Are the transistors marked for each drive? Would it be a good test to swap them from one of the other drives?

[machintek]

I have seen cheap rebuild kits. I have repaired countless heads in my career. I had to guarantee my work. Thus I had to buy factory varidiscs because they would run true and were balanced. I believe with a complex fixture you could glue in new bushings where everything will run true.
Also I believe the "clutches" are probably worn out. A dis-assembly will prove that out. They engage in high gear. They are part of the splined gear hub and spindle pulley hub.
The splined gear hub also supports the bull gear and bearings for the back gear.
Probably the transistors blew when the drives shut off while in a rapid up. This is common. Later on Bridgeport installed a SMS board to cushion the drives when shutting down while moving. The transistors are mounted on black pieces of aluminum on the right logic cabinet door. Yes that is a panel that opens with 1/4 turn fasteners. I believe they are labeled. If not refer to the wire numbers in the maintenance manual. Typically these short internally. Bridgeport specified a 2N6547 transistor.

George

[CincyTJ]

Originally Posted by machintek I have seen cheap rebuild kits. I have repaired countless heads in my career. I had to guarantee my work. Thus I had to buy factory varidiscs because they would run true and were balanced. I believe with a complex fixture you could glue in new bushings where everything will run true. Also I believe the "clutches" are probably worn out. A dis-assembly will prove that out. They engage in high gear. They are part of the splined gear hub and spindle pulley hub. The splined gear hub also supports the bull gear and bearings for the back gear. Probably the transistors blew when the drives shut off while in a rapid up. This is common. Later on Bridgeport installed a SMS board to cushion the drives when shutting down while moving. The transistors are mounted on black pieces of aluminum on the right logic cabinet door. Yes that is a panel that opens with 1/4 turn fasteners. I believe they are labeled. If not refer to the wire numbers in the maintenance manual. Typically these short internally. Bridgeport specified a 2N6547 transistor. George

thanx, digikey has those transistors for $5 each. Is it best to replace all 12? Do they age?

also, is there a good source for a rebuild manual? Is there someone that sells factory parts kits? Do you think I should buy a kit or just pull it apart and replace worn or broken parts?

[CincyTJ]

ok, I did a continuity check. It actually sems right looking at the attached picture the following terminals show connected.
1-6
2-8
3-5
4-7
none are shorted to the case.

I swapped the x and z control PCBS and x stillworks and z does not. There is a plug unplugged on one of the computer PCB's should this be connected?

the transistor cluster is all soldered together. I Ohmed the right side lead to attachment screw on all of them and it is 150-160 except for the second one down which gives 0.01 ohm. seems like thats it. I guess I will order some transistors and get to soldering.

[machintek]

Let me guess, the unplugged connector is on the ERS board. That gets unplugged for RS232 communications.
Yes that is the shorted transistor. You can replace only the one if the rest are 2N6547.
All 4 must be the same.
Get a maintenance manual from machinemanuals.net.
Search this forum for a lot of data on these machines.

George

[CincyTJ]

still looking at transistors. I found a couple substitutes with higher power ratings, anyone have experience with substitute transistors for the drives? I can get a better power profile from a BUX98A but it has 7V emmitter base voltage as apposed to 9V on the 2N6547, but it is 1000V and 30A peak. I can also get darlington transistors much cheaper with higher volt and amp ranges, anyone tried darlingtons?
thanx

[creep_pea]

This is a good post NC cams wrote about the different transistors that will help you:

You might want to look at bypassing the inductive load with an appropriate diode to kill off the inductive feedback. I suspect that this is what the SMS board is supposed to be doing. If you don't have such protection, you probably should figure out how to get it.

Keep in mind that diodes don't live forever - should they start to "zener" as they age in that they will NOT protect like they used to do when new. It might be time to replace any diodes in the protection network for the reason already cited.

1N4001's will NOT work although some folks use them for simple relay bypassing - you need some real fast Schottky's for inductive motor use, especially when you're doing ultrafast switching as during jog's (could this be why jog's cause more problems with blown transistors????)
I'd buy the fastest, highest current rated ones I could find and afford to protect the devices.

Transistors: After perusing several threads involving this subject, it seems that semiconductor development has transpired since the machines inception resulted in various parts being used in various machines. Also, newer, more robust devices are available for service

In order of introduction/evolution, the transistors were as follows:

2N6547 (400v, 15 amps. 20 amp peak)

then the

BUX48A (450V, 15 amps, 30 amp peak, 60 amp overload, 2nd generation of the transistor series)

then the

MJ16012 (450v, 15 amp, 20 amp peak, 3rd generation of the transistor series)

then the

MJH16012 (same rating as MJ16012 but more gain at same base current).

MJ16014 (450v, 20 amps, 30 amp peak, gen 3)

MJ16016 (same rating as MJ16014 but more gain at the same base current)

The "high gain" versions transistors should "turn on harder" than the "regular" models at the same drive. This should reduce heating effects caused by less internal resisitance while conducting.

At this point, the MJ16016 is probably the most robust part you could possibly use in the application.

It can not be emphasized enough that the use of 'brand name' part numbers as opposed to "aftermarket equivalent/consolidation" p/n's will offer the best possible chance of achieving the rated performance of the high performance transistors.

[CincyTJ]

unfortunately I dont have the schematics. one of the EE's at work also suggested diodes to protect from flyback. for now I am going to try just the transistors, when I switch to Mach3 with a BOB and gut the system I will see if my EE freind can look it over to see if added protection can be implemented. I dont want to get too fancy now since once this machine starts paying I will do a full blown conversion with geckos, for now Id like to limp along on the BP systems using the steppers and drivers already there