Fadal VMC4020 air regulator pulsing

[emexcee380]

Guys,

We have a mid-90's Fadal VMC4020 with CNC88HS control. Recently it began showing an alarm: "WAITING ON AIR VALVE" after powering on. This was accompanied by the main air regulator "pulsing". Usually after a few minutes the air regulator would stop pulsing and the alarm would clear.

I noticed that we could not shift from LOW to HIGH range via "S.1" or "S.2" commands per the manual.

It seems that perhaps the one or both of the solid-state relays that shifts a solenoid valve from one range to the other must be faulty. Our manual lists a relay "K10" for low range and a relay "K27" for high range. Our relay board has neither a K10 nor a K27 relay.

Can a knowledgeable Fadal guy chime in and confirm my diagnosis or suggest an alternate idea about this fault?

How do you check output signals on this control? It would be nice to confirm that the outputs are being sent.

What is the FIN signal for selecting either HIGH or LOW? Is it just the output pulse?

Our relay board is an "1100-2D" model that has both solid-state and ice-cube- type relays. Which relay is for HIGH and which is for LOW?

Any help will be appreciated.

emexcee380

[emexcee380]

Well, I found part of my problem anyway. The two solid-state relays that I was looking for are apparently on a relay board "1100-1" located in a side electrical cabinet, not on the "1100-2" relay board in the rear cabinet. (Hey, I'm a rookie with Fadal's !!!)

I've ordered new relays from Fadal CNC and should have them in a day or so.

Can any Fadal-guru either confirm my idea that one or both of these relays is faulty or is there a better idea of what's causing our regulator to "pulse".

Any help will be appreciated.

emexcee380

[denmar]

bLACK OR GREEN RELAYS DON'T FAIL;
IF YOUR MACHINES IS EQUIPPED WITH A BLUE MAC VALVE ASSAMBLY, NOTICE THAT THERE IS TWO SOLONOIDES SIDE BY SIDE AND TWO IN LINE; THE TWO SIDE BY SIDE ARE THE HI AN LOW VALVES; THE ACTUATOR(S) HAS A LITTLE BOTTOM IN CENTER, USE A POINT TO PUSH IT WHEN IS CLICKING, IT SHOULD SWITH RANGES. MUST LIKLY THAT IS THE PROBLEM, OR THE HI AND LOW IDLER ASSY. IS GETTING STOCK.

[emexcee380]

Denmar,

Thanks for your response.

Our machine has five (MAC) solenoid valves in a row on the bottom of the rear electrical cabinet. I haven't found a pneumatic schematic that identifies the function of each, but I assume one is most the HIGH range and another is the LOW range. I don't see any sort of pin to manually actuate the valve, but I'll look again today.

If one or both of the solenoid valves was not shifting I think (as you suggest...) the regulator would "pulse" as it open one circuit and close another.

Thanks again,

emexcee380

[DareBee]

Yep it is likely your valves and the problem is usually caused by the long term effects of moisture in the air.
For what it is worth, I would (and have) change out all the valves and the regulator.
You dont need to use Mac valves.

[denmar]

Ok, so then you have the five in line black mac valves mounted on a manifold?
Do this: find wich are the Hi & low valves, switch one with the draw bar valve and press
TOOL in/out at the keboard, if is bad,it would buss or leak.

[emexcee380]

Denmar,

Yes, there are five solenoid valves mounted front-to-back (i.e. parallel to the Y-axis....) in the rear electrical cabinet.

I guess I'll have to follow the wires from each to the relay board to determine the functions. I don't see a manual pin on the valves to press to shift the valve. Is there one that I'm missing?

I'm guessing the five valve functions are: drawbar unclamp, carousel in, carousel out, spindle airblow, High range, Low range.

I like your idea about swapping solenoids. If the solenoid is faulty, the problem should follow it.

Thanks,

emexcee380

[denmar]

You don't have to remove the valves, just the air hoses; valves are: spindle orient, draw bar (tool in/out), Hi & low range, spindle blower. The ones with the botton are the old style Mac valves assy.

[emexcee380]

Hey guys,

I couldn't get back to the Fadal with the pulsing regulator until yesterday.

Here's what I found:

The command " S.1 " should cause the HIGH RANGE cylinder and pulley wheel to retract and the LOW RANGE cylinder and pulley wheel to extend.

The command " S.2 " should cause the LOW RANGE cylinder and pulley wheel to retract and the HIGH RANGE cylinder and pulley wheel to extend.

There are two prox. switches mounted near the cylinders to detect that one or the other is retracted. There is no confirmation that either is extended.

After identifying which solenoid valve controlled the LOW RANGE and which controlled the HIGH RANGE, I was able to determine that it was the LOW RANGE solenoid that was actual pulsing and causing the regulator gage to pulse as well.

My original thought was that one of the solid-state relays that controls these functions was faulty. So with the LOW RANGE solenoid pulsing I checked the voltage (110VAC) out to each solenoid valve. There was 110VAC ON for both solenoid valves simultaneously. ( I said to myself, "Self, that can't be right.....")

So I removed and replaced the K10 (LOW RANGE output) and the K27 (HIGH RANGE output) solid-state relays. VOILA !! The pulsing stopped and the LOW to HIGH shifting worked correctly when "S.1" and "S.2" were commanded.

Be aware that the solid-state relays are not actually surface-mounted (soldered) to the relay board. There are female socket pins soldered to the board and the relay pins simply insert into these. You can remove the relays by wiggling them out.

I worked on this for about an hour before taking the board out and asking an assembly tech for help. She looked at the relay and just pulled on it and it popped out. "DOH !!!" (Homer Simpson moment...)
What should have been a 60 second relay removal turned into a 60 minute board removal and replacement procedure. (Again, "DOH !!!....)

I hope this message helps someone in the future with a similar problem.

emexcee380