need help please!

[2ezy]

have mori seike sl4 with 6t control, when powering up green led on power supply lights up, when power on button next to crt is pressed contactor pulls in and drops out red alm led under green led lights up, all fuses seem to be ok, any clues?

[tc429]

24 volt dc short 99% of the time. have also seen blocking diodes on the 6B-2 mother board relays short and cause it- a 10 cent diode a much easier fix than a thousand dollar board swap :P

a bad supply will do it too, but often theyll blow 200v fuses. a bad relay on the 'input unit' (where the red/green lights are) can cause t too, but usually those just quit lighting up at all, usually due to little transformer leads breaking off at the solder points...machines that vibrate a little much do that every once in a while...

suggest unplugging your I/O card plugs and seeing if she'll boot up- if so, just a simple(but hard to find) 24 volt short. turn the main off, plug your i/o plugs back in, and if youve got a Fluke or other DMM with the low ohms scale (0.01 ohm resolution), check from ground to all your 24 volt terminal strip points- things like decels are normally closed, so if one shorts, they all look shorted- but on low ohms, the lowest observed will lead you to the culprit quickly. 99% of the time it will be a overtravel/decel/turret switchbox or terminal block thats full of coolant or corroded.
IF you cant track it down, unplug all the brown connectors except the Master pcb, theres test pins on there for +24 and 0v, if its still shorted, check the diodes next to the reed relays on the master- if you find one shorted and dont have desoldering equipment, just snip the leads close to the diode, bend them up and tack another one on there...its not like youre gonna void the warranty on a 30 year old part
Tim

[2ezy]

Thanks very much for your prompt rely, this information is invaluble, I will start working my way through what you suggested and see how I go,thanks once again.
John

[underthetire]

I agree. Typical sl4 failure is the cable that runs over the top of the control cabinet, through the cable track, to the turret switches. You should be able to unplug the harness on the io board to test. Not to bad making and replacing the cable.

[2ezy]

Thanks for your help so far, I have found that disconnecting the small lead marked C3 from the terminal strip in the control box on the side leading back to the nc cabinet allowed me to boot it up, most functions worked in manual except the turret indexing, the turret lifted then stopped. I do not have schematics for this machine and was wondering if you have any ideas.
regards John

[2ezy]

Thanks for your rely, the problem seems to relate to a wire marked C3 leading back from the control cabinet to the nc cabinet, still trying to work out where that leads.
regards John

[tc429]

Originally Posted by 2ezy Thanks for your help so far, I have found that disconnecting the small lead marked C3 from the terminal strip in the control box on the side leading back to the nc cabinet allowed me to boot it up, most functions worked in manual except the turret indexing, the turret lifted then stopped. I do not have schematics for this machine and was wondering if you have any ideas. regards John

man, no schematics will make it fun...I would power it down and start gently tugging on wires to see where it goes- sometimes youll need to pull almost everything out of the panduit and cut wireties if they bundled them up- just be careful if trying to fish around and follow where it goes- a lot of time on old stuff its easy to pull a wire or ringterminal off and have no idea where it went...
we got a okuma in a couple weeks ago, had a 24v short, I tracked from the supply thru the cabinet- must have cut 100 wireties. friggin okuma packs like 5 extra feet of cable into each panduit, had a spaghetti bowl to clean up afterwards...was soooo paranoid about pulling a wire loose while fishing/following this one stupid wire that seemed to loop around everythig three times...anyway, in the end found a stupid door switch cable had been snipped off and was just laying on top of the machine under a bunch of other wires grounding it...several hours and the problem was right out in the open...I was so pissed at myself

theres a lot of mori seiki fans out there- hopefully someone will chime in...just to clarify- are you unhooking a single wire labeled 'c3', or is it a cable with a multi-pin plug labeled 'c3'? good luck