Vista VT300-34 No High pressure

Hello everyone. I am new to this site, as you all can see. I am a technician at a job shop here in Florida, and seem to have walked into a bit of a dilemma. I have a number of Milacron machines on the floor, and they all have problems to one degree or another. the current issue on 2 of my machines, that are identical in control and build, well, I have no high pressure at all. Mind you, the controls were both sent out to DC Repair, and have been validated for operation. both rexroth cmc-1 cards have been checked and verified. All jumpers have been checked and verified. At initialization of the machines, 0-10v has been checked, DC24v, has been checked and verified, have followed the Valve driver set-up to the letter. However, in order to really do anything with the setup, there must first be pressure in the system. My current idle pressure in both machines is 150-200psi. i have checked at the transducer on the injection manifold, and at MP1/MX6 test port, barrel has been warmed up to 350F, polypro purge material loaded in hopper, pump stroke set to 10.00 in the factory screen, and have run to p200 up and down to get pressure. At this point, I still have nothing when punching up the pressure demand by activating the injection. Basically, from start up, I have no High pressure in both machines. Prior to any repairs to electronics, BOTH machines were running WITHOUT hydraulic issues. Also checked main pump, oil levels, P-213 poppet, p-212 valve, P-232, and have even interchanged parts between both units. The only thing I can think of, at this point is a setpoint in the logic that was lost during repairs. But, I am simply stumped at this point and desperately need a lead in the right direction. Milacron has been pretty much useless to this point. Has anyone experienced these issues after a rack repair??????????

idle pressure seems really low, typically around 450 on a newer VST

i would check the pressures against the hydraulic print before you dive into the electrical rabbit hole. On a newer VST poking the Extruder load sense or load pump with a screwdriver it ramps the pump. if it doesn't, probably have a clogged orifice.

on the newer machines every time i change a board, it requires reloading the program, not sure about the older VT.

have already checked the hydraulic pickups in both of my machines. Mind you, BOTH of my machines have the identical issue of No High Pressure. Both were working, prior to other issues that forced me to pull the controls and send in for repair. DC Repair has been working closely with me, in troubleshooting and looking for anything electrical or mechanical that may be causing this issue, to no avail. I am hoping that someone out there has experienced this issue before and can relay what I am looking for, to correct this nightmare. I will however contact Milacron and obtain the software again to reload the PLC and see if it corrects the problem. Is there any specific software that I will need for my laptop, that will allow me to do the upload via the rs-232 port on the PLC?

i am not sure what mailacron will sell the software to load it into the PLC but they charge around 1k for the plc program/ screen software on the ~1995 vintage machines.

you will also need a old windows 95 computer to run MSDOS, the newer ones will not work.

maybe contact field service and ask about the runoff procedure. in it there are some ways to load the pump and do some different things that may be helpful.

what controller/workstation is on the machine camac ??? if the screen and plc works i highly doubt that is the problem, we only reload the program as the last resort. or if it lost memory due to a power outage or something

As of late, milacon has been useless in troubleshooting. As it looks, I have no pilot pressure to the PV-1 solenoid. However, the pumps are functional and pilot pump is working and pushing 400 psi, directly from the pump. I am thinking there is a shuttle valve hidden inside somewhere, but cannot seem to get a sequence of the valves firing in the logic. perhaps, after the repairs to my racks, something is firing in the incorrect sequence, and it is preventing me from getting my system pressure control running.

do you happen to have the hydraulic print or at least the numbers so i can check in our obsolete pile of prints for something close.

I have the print provided from milacron as a general print, but it is useless and does not have the physical hydraulic circuitry, aside from the general overview. The print that I have is 3991312105.

Did you ask service for a hydraulic diagram ? 3991312-105 should be a machine diagram

also who did you speak to at Milacron?

Attachment 505

image of a standard data tag. not sure if the older machines are the same or not.