Need Help!- Brpt series 2 Boss 6...Z won't move

[grigsby]

My 1982 series II Bridgeport with BOSS VII machine sounds like something is slipping in Z . All axis have 9 +-1.5 volts on the DC fuses. all have 56 volts ac. I have exchanged z power axes with x axis, same. Turning over acc card does not move problem. I have replaced all transistors that were shorted. I made new heat sinks (15 years ago) that power transitors are mounted where you can remove 2 bolts and change each power transistor when they are shorted. I do not have to pull sink from machine to change transistors. My z axis still sounds like slipping gear. No power transistors are shorted. I will look for dropped bolts or washers that could show shorted P transistor. By the way a few (15 or so) years ago I bought 24 Harris transistors for $4.75 each. Still have most of them. All reactors have to the best of my checking ability, the same voltage on each of them. I bought this machine in 1992 and was broken when I got it. Paid "Bridgeport repairman" to fix it. He did not. I called service center and they sent me a RCK I think board and fixed it the next morning. I have replaced sn188 and sn189 photo isolator chips a few times after lightning kept blowing them off the board. I put sockets under them. I still would appreciate some advice on what I have missed on this baby. Thanks KW

[grigsby]

Originally Posted by grigsby My 1982 series II Bridgeport with BOSS VII machine sounds like something is slipping in Z . All axis have 9 +-1.5 volts on the DC fuses. all have 56 volts ac. I have exchanged z power axes with x axis, same. Turning over acc card does not move problem. I have replaced all transistors that were shorted. I made new heat sinks (15 years ago) that power transitors are mounted where you can remove 2 bolts and change each power transistor when they are shorted. I do not have to pull sink from machine to change transistors. My z axis still sounds like slipping gear. No power transistors are shorted. I will look for dropped bolts or washers that could show shorted P transistor. By the way a few (15 or so) years ago I bought 24 Harris transistors for $4.75 each. Still have most of them. All reactors have to the best of my checking ability, the same voltage on each of them. I bought this machine in 1992 and was broken when I got it. Paid "Bridgeport repairman" to fix it. He did not. I called service center and they sent me a RCK I think board and fixed it the next morning. I have replaced sn188 and sn189 photo isolator chips a few times after lightning kept blowing them off the board. I put sockets under them. I still would appreciate some advice on what I have missed on this baby. Thanks KW

Well---
I got my boss6 running.
When I put back in drive transistor heat sink I crossed two wires. Number labels had fell off and I was not diligent enough. I analized what I had did since machine quit. I had changed drive transister heat sink. So I had knocked off wire labels in the process. GOOD advice is to make sure all wires are labled properly before removing wires. Cost me 6 weeks of agrivation with my other jobs. Now I have drive transistors where they can be changed without removing heat sink. I hate to solder on transistors. Bridgeport made a BIG mistake. Or was this their job security? If any wants some info on changing heat sinks, email me. Thanks for insite to analize my problem. KW