[craig96us]

I am considering replacing the control with gecko's etc, but in the meantime, I really need to get my Y axis running again so I can make some parts!

The failure occurred during a 20 minute or so period of time when the machine was sitting idle.

Specifics:
I pulled the front belt cover off to expose the position indicator drive, and allow me to see any leadscrew motion... If I try to jog the Y axis, the leadscrew shows slight motion in one direction, then motion stops while I can hear the stepper motor whine increase in frequency... When single stepped, the axis moves a step in the same direction each time. Positive, or negative direction motion is the same. Two sequential steps feel pretty solid, the next two feel weaker when moving in the - direction. In the + direction, all of the steps feel a bit weak.

There are no blown fuses...

Is this a common failure, and if so, what components should I be looking at? I have a maintenance manual, so I should be able to locate parts/testpoints etc.

TIA for any tips anyone can provide!

[craig96us]

A little more info:
I flipped the ACC board with no change, and swapped SMD with Z axis SMD, and no change...

[harolda]

replace 4 transistors on the transistor pack on the back door

[puller482]

I had the same problem the transistors will fix the problem. I keep an extra block of transistors as a backup. They seem to use these from time to time.

[craig96us]

Thanks!

I will replace the transistors and let everyone know what happens!

Actually my troubleshooting so far has lead me in this direction, so this tactic is right on track with what I am finding on my own!

This forum is a great resource, and I am grateful for the advice. Bridgeport information, and repair advice is getting quite scarce these days!

/Craig.

[puller482]

Craig here is a link to some files if you scroll down thru them you will find some info on changing those transistors. Be sure to use the heat sink compound when installing the block back on the heat sink.

Good Luck
http://metalworking.com/DropBox/_2000_retired_files/

[machintek]

It is also possible that one of the 12 diodes on the board beneath the ACC card is bad. When on of these goes, it does what you have described. By putting a meter on the base of the transistor, I notice that they do not turn on and off crisply. Instaed they turn off half way then finally off fully. By the way, the ACC is symetrical and by turning it around, you switch the X and Z current circuit but not the Y. In twenty years of BPT service I have only found one blown SMD board.
I cut and pated another answer in part below. Just substitute Y for Z.
Put the machine in jog, setup, z axis and step. Press the minus button repeatedly. Each time you do watch the small shaft and dial benath the Z axis motor. Made sure that it does not step in the same direction for three steps and then reverse direction for one. This would indicate a shorted final drive transistor (2N6547). There are 3 groups of these on black aliminum heat sinks above the ACC board.
It is also possible that your voltage in is wrong, you have a bad bridge rectifier, your current is set wrong, you have a chip or washer between two diodes on the small board beneath the ACC card, a chip or washer in the motor terminal strip beneath the ACC card, or the wrong transistors, or a high resistance in the Z axis DC fuse (screw in type, tan in color), or your quill needs to be cleaned with kerosene and use Mobil Vactra number 2 for way oil. I also once had a bad opto coupler on the ZDI to the SMD. Drove me crazy.
That gives you a bit to check.

[craig96us]

I will check the diodes as you described. I am at work right now, so I can't fiddle with the machine until later this evening.
I found the post that you pasted in yesterday evening while I was searching for more information that might help me fix this thing! After single stepping the axis, and not seeing the backstep, I decided that I should post my problem and see if anyone could help.
Your description in that post, and obvious knowledge of the inner workings of the stepper drive circuits is what prompted me to post my problem here! Thank you very much for being willing to help and share!
Based on what I read here, I now know that I may have a diode problem, and replacing the transistors could be an exercise in futility. I will have to determine if the diodes, or the transistors are at fault before I start shotgunning parts...

I will post what I find!

Just for fun, I am attaching a photo that my wife took of me working on interfacing my laptop with the BOSS6 so I could transfer gcode programs etc...

[craig96us]

Craig here is a link to some files if you scroll down thru them you will find some info on changing those transistors. Be sure to use the heat sink compound when installing the block back on the heat sink.

Good Luck
http://metalworking.com/DropBox/_2000_retired_files/

I was able to locate files that appear to be related to diode replacement here, but I didn't see anything about the transistor replacement... Perhaps you can give me a filename? There are a LOT of files in that folder!
Thanks!
/Craig.

[craig96us]

The link that puller482 provided lead me right to the transistor plate! I found one of the power transistors to be shorted. I will be ordering + replacing. The transistor plate is a bit of a bugger to get to, easy to drop the screws etc.
Thanks a lot everyone! I will be making chips again soon!
/Craig.

[machintek]

How did the interface go? There are a LOT of posts about that in this forum also.
In another post I give a legthy description of how these drives work with voltage readings etc. If I find it I will post a link.

George W.

[craig96us]

How did the interface go? There are a LOT of posts about that in this forum also.
In another post I give a legthy description of how these drives work with voltage readings etc. If I find it I will post a link.

George W.

The interface took some time to figure out, but once I had the pinout information for the amphenol connector, I made up a serial cable with a DB9 on one end, and nothing on the other. I pushed the individual wires into the correct locations on the amphenol! My intention was to get it working first, and connect more permanently once it was working. The hardest part of the whole thing was figuring out how to transfer files, and break off the connection once the file had finished transferring... I ended up using hyperterminal at 2400 baud. At the BOSS6> prompt, Hit K <enter> to empty memory, and put the BOSS into "Input" mode. Next I would use the send text file function in hyperterminal to push the Gcode across. Once the transfer was complete, I had to hit CTRL+Z to get the BOSS out of terminal mode. It was frustrating to discover that there is no flow control on the BOSS RS232, so I ended up having to run the interface at 2400 baud. Any faster, and it would drop random characters. Usually the first character of the gcode block here and there. At 2400 it is almost rock solid. I added a delay of 15msec between lines, and presto! I am still pretty disappointed that the memory is so small. The BOSS6 will only hold about 600 some odd lines of Gcode. Once I have saved my pennies for a set of Gecko 201's or 210's, I plan to replace the BOSS. In the meantime I will have to live with it's limitations. I also have a 4 axis Shoptask that I built a few years ago. I can use it for the few jobs that require more than 600 lines of gcode if I have to. However I really don't have a lot of interest in running jobs on the Shoptask now that I have experienced the obvious advantages of the Bridgeport!

/Craig

[machintek]

Procomm works well also. I have the BPT Communications bulletins on PDF format if you need it. Remember to use 2 stop bits, no parity, X on Xoff enabled. The large rectangular connector on the ERS is pulled out and left to dangle for RS232. The AMP connector is a reverse sex 8 pin type and I used to purchase it from Newark electronics. On a 25 pin, the pc side would have 4 to5 jumpered, and 6 to 8 to 20 jumpered. There is a VERY powerful editor built into the BOSS control. In PROCOMM, I use the CHAT mode for editing the program in the machine. If there is a program in the machine and you press the edit button, it will come up with BOSS _ editor. You can still upload a piece of code by using the INSERT mode. Two carraige returns returns you to the edit mode. KI will clear the memory and return you to input mode. There is an entire page of editor commands.

George W.

[harolda]

bud you look like like my brother but he hates machines.
Do you have the programing book ? You know i had the same problems with the droped cariator also.I had one boss machine that had 20 ma loop that worked better . Since all the transistor pack blown out i used other drives thay work wonderful . With maxnc software. :cheers:

[machintek]

ALL BOSS 3,4,5, and 6 machines could communicate in 20ma current loop. But it was extremely common to blow the transistor in the loop on the ERS board. 20ma was used with the Type 33 teletype. The Type 43 could do both 20ma and RS232. The problem is that the serial port on a PC is Rs232. Pins 1,2,3,4 and 5 on the AMP connector were used for 20ma. Pins 5,6,7, and 8 were used for RS232. Only the local port on the machine is available.

George W.

[mc_n_g]

Here is a copy of a post I replied to on the BobCAD forum a while about. The terminal/editor I am referring to in the message is Tera Term. It is free and I use it to talk to my Bport BOSS-5. Use the following link to go to the Tera Term page.
http://hp.vector.co.jp/authors/VA002416/teraterm.html
I purchased the cable from Jim Blasko about 2 years ago and have never had any regret in the purchase. He is still selling the kits/cable. I am in no way related to him and I do not make any money on any sales.
It is a pain in the ass to break up your program in 13K chunks but it works.
Hope this helps someone.
mc_n_g

beginning of post
************************************************** *****
I have a Bport BOSS 5 Series I CNC machine I run with BobCAD generated Gcode.
I use a cable connection designed by JCM Blasko of Lake Oswego OR (near Portland). He has a RS232 kit for sale that bypasses the old connection and splices into the wires of the communications boards. You send your code to the machine via a Hyperterminal window (program). Basically you start an editor to 'talk' to the machine and download the code to it. Once the code is downloaded you turn the dial and hit Start button on panel.
I have reached a maximum file size of around 13,400 Kb file. Yes it is small but remember this is ascii text only so there can be several hundred lines of code. When my programs become too large I just break them up into smaller pieces and feed the program in chunks to the machine and run the whole program in several parts. For the most part this only comes into play when you are creating skins or very complex parts.
The cost is around $70 for the cable, directions, and terminal program.
It is well worth the investment rather playing with the old style serial port.
I noticed he is currently running an auciton on EBAY and selling some of the cable kits. The link is
http://cgi.ebay.com/ws/eBayISAPI.dl...&category=11805

If the link does not work look for Bridgeport RS232 as key words. You should find him with a few other listings.
He is a nice guy and can answer questions you may have about the set up of tha cable and the machine.

If you need more info contact me through the board.

mc_n_g
************************************************** *****
end on post

[mc_n_g]

Just as another note. I also have used the Metal Working Drop Box files for replacing the transistor/diode in the Bport. Make sure you use a heat sink when soldering in the new transistors. The cost of the transistors is around $10-$15 each.
Everything worked fine after replacing the 1 that blew.
One way to tell where your problem transistor is located is to swap the transistor boards. If your X-axis is not working right swap teh baord with one already working on the machine (say the Y-axis). If your problem transfers from the X-Axis to the Y-axis you know the transistor you need to replace is on your board and not on the large heat sink at the back of the machine. If your problem stays with the X-axis then you know to look at the transistors on the large heat sink at the back of the machine.
There are 4 transistors per board and 4 transistors mounted on the heat sink on the back of the machine for a total of 8 per axis. 24 total for the machine.

mc_n_g

[machintek]

A meter set to diode check (which measures voltage drop across a semi-conductor junction) is the quickest way to determine if a transistor is bad. First do the step test. If the mechanical counter goes forward, forward,forward, back, etc you have a blown (actually shorted) transistor and the voltage drop will be zero.
It is a lot quicker than swaping transistor blocks. Also the less you remove these, the fewer washers and screws you will drop onto the diode board or the motor terminal strip. Transistors are 2N6547 and any BPt tech carries a dozen, as well as a couple of bridge rectifiers. These final drive transistors are driven by the SMD boards. In twenty years of service, I have only replaced one of these.

George

[braidmeister]

Yep...I bought a bunch of these transistors in question. I have 9 of them brand new for sale if you want them. $35 shipped USPS Priority in the US. Contact me if interested. I no longer need them since I am converting to servos.

-Brady

[craig96us]

Well Guess what...

I replaced the shorted transistor for the Y axis, and another one that was reading different than the others, but wasn't shorted... I figured this other one was marginal. After putting the thing back together, I put power to it... Y axis works great! Cool I thought... Problem solved. WRONG... The X axis won't jog now... I popped the machine open and put my meter onthe transistors for the X axis... One shorted, and another marginal... Replaced the shorted one... I vacuumed the control cabinet to make sure that I hadn't inadvertantley shorted womething by brushing a chip inside or something... I was careful with my repairs and didn't drop any screws etc... Powered back up, and no X axis jog... Powered back down, metered the X axis transistors... The marginal one is now shorted. I replaced it. I figured I must have done something while I was in there, so I double checked every connection, and checked for shorts before putting power to it this time... Damn X still not able to jog... Three steps forward, one step back! Multimeter confirms that the transistor I just installed is now shorted.
I have bought all of the 2N6547's that I could find within driving distance (4)... I need more, but I am concerned that I must have done somethig while I was in there that is killing transistors on the X axis now...
Any ideas? This is pretty frustrating!!!!

TIA!

/Craig.