[zy0x]

Howdy all, Another issue with the 1996 sabre 1250 with the a2100.

The machine loads and all the diagnostics pass, the screen has no issues until you hit the green power button to turn the machine side power on, the screen begins loosing the display and flashing to a black screen. Visible horizontal interference "lines" slowly roll up the display, this only happens while the machine side power is on.
when you run a cycle the black screen gets even worse, to the point it is pretty much flashing black every second.
some days it is better then others, might only flash black 5 times on a good day.

The display is vga and comes directly from the WS board, the vga cable is in good shape.
the kti board also passes diagnostics and the touchscreen works (though It is had the fail light come on this board before)

It was originally a crt display and was changed out to a monitech lcd.

Any idea what could cause this?

[gwood]

The original VGA monitors got their AC-power 120VAC from the power supply 2nd plug. If it only happens when the drives are on it seems to be a power glitch or noise.
Is the incoming 3 phase power 220-240 line to line and balance within 2-3 volts? Are they the same once the drives are started?
The Kollmorgen drives were designed to be run on WYE power, Not Delta.
This is why a Delta to Wye transformer was supplied with a new machine.
A good Ground is critical as well.
Are all of the fans running? The A2100 power supply, Drives, Cabinet, the Resistor bank on top of the cabinet, Z-Motor cooling fan?

[zy0x]

Hey Gwood!
I got around to checking the line to line voltage, for the most part they are right at 230v (+/- 1v), one leg is a bit high at 239v, they dont change much when the drives are on/off.

I have the original transformers for the two a2100's i own, both the machines are running off delta as thats what the transformers are (no 4th wire/isolated neutral, just 3 hots and a ground)
both the cincinnati supplied transformers are running off the same Wye-Wye 112kva transformer, and the lathe does not have any issues.

all the fans are running with the exception of one in the Z axis bds4 drive,which has been non-functioning previous to the screen issue

[gwood]

You could plug an old vga monitor in and using an extension cord to power it. this would remove the display from the equation.

[zy0x]

I got around to checking grounds, all ground connections to the drives and computer, they seemed tight and measure good with basically no resistance.

I moved on to checking the power supply (PSR4/5-275-7500) for the drives, i believe the output dc voltage is supposed to be 310vdc
I noted it was a bit high when the machine is at idle (330vdc)
I checked AC input voltage and it was fluctuating from the lowest being 215v to the highest being 240v, but normally hovering at 230v across the 3 phases.

I started the spindle at 500rpm to see what dc voltage we would get to the drives.
I have no idea how, but dc voltage was all over the place, 1300vdc to 600vdc depending on the drive. The spindle drive's DC input bus was at 1300vdc...

I changed the rpm to 1000rpm, and the spindle drive voltage dropped to 500vdc while the PSR was running at 115vdc

I think this concludes the main PSR drive is bad, unless i do not understand how the drive works?
Somehow the machine has been running like that, no other issue then the screen.

[maver1ck]

Since you mentioned you weren't having any issues with the machine other than the display, with those readings I would start by getting a new meter. Voltages should be stable, and your DC BUS definitely shouldn't be going that high so I suspect your meter isn't giving you good readings.

Incoming AC voltage should be stable if you have proper wiring to the machine. If your AC voltage is dropping while running the machine, I would assume your supply is being choked off so you need to figure out where that is happening and correct it. Are you using the factory transformer with the machine? Are you running a phase converter (and is it capable of the load your machine puts on it)? Under normal circumstances I would not expect the AC supply voltage to drop by more than 5-10VAC no matter what load your machine is putting on it.

With the machine powered up and at idle, at a 230VAC input to the PSR I would expect DC Bus output to be in the mid 300s VDC. A nominal amount of fluctuation is "normal" when a load is put on it, (i.e. dropping to 300VDC when spindle is ramping up and axes moving to position at rapid or rising to 380VDC when spindle is stopping), but these increases/decreases should be controlled and return to nominal once the load is removed.


But back to your original issue of the screen flickering..... You previously mentioned the CRT monitor was replaced by an LCD so I don't know what display you actually have but the last time I saw what you described, it was internal to the LCD display. The manufacturer installed a thin metal reflector behind the display that was taped in place. As the tape aged, the reflector started falling down and was pulling on the wires to the inverter. I taped it back into place, reseated the inverter connector and issue never came back.

[zy0x]

Hey Maverick! Thanks for the reply.
The machine is running off a legitimate 400A 600v 3ph wye service, A 112kva transformer runs both the factory cincinnati transformers i own for the a2100's to get it to 230v, the Hawk lathe does not seem to have any issues with it.

The AC main's are stable, i only see those fluctuating a couple volts coming into the machine, but i measure a bit of fluctuation on the 3 leads going into the PSR.. i would have to test further with another meter to ensure, but i have not had issues with the current meter.
The screen only flickers when the bds4 drives are powered on (its a Monitech lcd display with vga running from the WS motherboard) the Monitech lcd has a sort of diagnostics light, it turns red every time the screen goes black (loosing video input)

whatever is causing the noise, is happening when the machine end is given power.

[zy0x]

I have purchased a new meter and Maverick was in fact correct, the old one was junk.

the Dc rail for the bds4 drives are stable at 330v running at any given rpm range
the input voltage to the machines is stable at 230v-240v depending on the legs measured, it always measures 60hz

In the machine, (checking various contractors and leads for the bds4 drives) Hz is stable at 60 until the machine is powered on and running, then it fluctuates +/- 10hz.... but i have no other meter to guarantee this
I powered the other a2100 machine up and it acts the same.

I will have to probe around more.

[zy0x]

Well, After some more work the problem was the lcd
no idea why it only malfunctions when the drives are on, but hey at least its an easy fix.