Turbomolecular pump troubleshooting (EXT255H with EXDC80)

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Arun Luthra
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Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

I'm trying to get a turbomolecular pump to work. It's still in the return window if needed, but I would hate to waste time on that if it isn't necessary.

It's an EXT255H with EXDC80 drive module.

I'm using a 30V, 5A DC power supply connected to a DC booster to boost it to the required 80V. It's supposed to draw up to 1.1A and about 90 W, so I hope this power supply is enough (naively, it is, because it can supply 150W...). I set the power supply to 30V and the booster to output 80V, which checks out with the voltmeter.

The green status light turns on. The TMP normal status voltage is 6.5V when switched off. When the pump is switched off, it nevetheless pulls about 0.3 Amps and the drive module gets warm after a few minutes. When I close the switch to turn it on, nothing happens -- the green light stays on, the blades seem to do nothing, and the current stay stays exactly the same. I think there was 17 mV on the speed output (the analog speed indicator is 0 to 10V, indicating 0% to 100% speed).

Drive module:
https://www.idealvac.com/files/manuals/ ... s-Data.pdf
pump:
https://www.idealvac.com/files/manualsI ... Manual.pdf

Does the current draw and warmth set off any red flags? Or, is this normal? Any thoughts on why it isn't working?

I use a backing pump to bring it below the required starting pressure prior to switching it on.
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by John Futter »

Its easy for someone with your name all you have to do is#^$%^^
#$%&*$%&
$#^#$%^**%%^*%#$%#^@%
and there you are
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Richard Hull »

Needless to say, as John alluded to, real names only for real responses.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

Updated profile
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by John Futter »

Do the phase leds light??
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Rex Allers »

Please read the rules that you agreed to when registering.
They can be found here:
"Fusor.Net Policies and Procedures"
viewtopic.php?f=47&t=10508

New users often miss:
1) You must create your account using your real first AND last names as the LogIn/UserID.

2) New members are required to introduce themselves in the "Please Introduce Yourself" forum prior to posting elsewhere.

Arun,
Thanks for fixing rule #1, but I think you still owe us #2.
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

None of the red phase LEDs turn on.
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Jerry Biehler »

Sounds dead to me. But make sure your switch is connected to ground and not 24v. It pulls the start switch low to start.
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

Yep, the switch closes to ground / the negative pole return line. The negative and ground are very close in voltage. I've tried both. The instructions say to connect it to the negative sink of the 80 V power supply.

Given that the EXDC80 is heating up, is it likely to blame a short circuit inside the EXDC? I looked inside, but not obvious problems. That was a longshot to see a problem inside.
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Jerry Biehler »

How much is it heating up? Its going to heat up some what just dropping the 80v to the logic levels a lot of the circuitry runs at.

But generally speaking, something is wrong. I would put a scope across your power supply and see if you see a power sag when the turbo tries to start up. I have had an issue where I didn't have a beefy enough power supply to get the turbo to spin up to full speed.

There is also a possibility you have a variant of the power supply with different pinouts. I ran into that on one of my pfeiffers. Are you measuring 24v on the start pin?
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

I acquired a second EXDC80 and everything is much the same.

When off, the start pin 1 reads 6.5V relative to 0V on the supply. According to the manual, it should be 4 to 24 V d.c., so it is within range...

I have a DC power supply connected to a voltage booster. The DC supply is supplying 30V and reports 0.22 amps. The 80V output on the booster is pulling 1.0 Amp.

I close the start pin to the 0V on the power supply.

My 30V power supply has +, -, and ground. I connect this ground to the ground on the pump, and the ground pin on the EXDC80 (pin 3).

I don't have an oscilloscope, but the DC supply has no change at all when I switch from off (open) to on (closed).
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

If the DC power supply is at 30V and 0.22 amps, that is 6.6 Watts.

I don't understand why the 80V is at 1.0 amps. That is 80W, which is supposed to be the full current load when the pump is on. I measured this by putting the meter
leads on the + and - terminals of the 80V DC booster. This is incompatible with the 30V/0.22A displayed on the DC power supply.

Meanwhile, the 6.5V on the start pin times 1.0 amps is 6.5 Watts??
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Chris Giles »

Hi Arun

are all of those figures measurements or programming settings? With power supplies that allow you to set the current and voltage they can run in constant voltage or constant current mode and this may not be obvious. The settings work as limits, i.e.:
- if you set the current at a value lower than your load will consume at the voltage setting, then the PSU will reduce the voltage until the current does not exceed the setting - this is CC mode
- if the voltage is not limited by the above then it will be set to the voltage setting - this is CV mode.
Your PSU may display the limits rather than the actual values. If you are not sure, then experiment with a resistive load and measure the current and voltage independently with a DMM then try to alter the settings. Be careful not to exceed the current which your DMM can handle.

Example: with 100R, 1W resistor @ V = 10V:
- it will be in CV mode if I set @ > 0.1A
- it will be in CC mode if I set @ <= 0.1A, then you will see the actual voltage dropping below 10V

Specifically, given what you said above, is the 1.0A current on the 80V output a setting or measured using a DMM in series with the load (Turbo PSU) at the same time as measuring the voltage across the load (80V?) ?

regards
Chris.
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

I got ANOTHER pump and it is showing the SAME problem. Either my DC power supply is not working, or the DC booster, or (most likely) my wiring or configuration is wrong.

The DC power supply says CV mode, it displays 30V and 0.22A, with the switch off. I measure 0.35A across the + and - leads of the DC power supply.

The current limiter knob on the DC power supply is fully clockwise to allow maximum current.

I measure 80V and 0.98A across the + and - leads of the output of the DC booster. I measure 0.98A across the pump load with the switch off, and switch on.

There is 4.0V between the start pin 1 and the ground of the power supply. There is 6.67V between start pin 1 and the - on the booster.
tmp-1.jpg
tmp-2.jpg
tmp-3.jpg
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by John Futter »

arun
your power supply is one of those super cheap chinese switchers
we bought one at work thankfully it blew up but it did not like talking to another switch mode down stream (in this case your upconvertor)
use a linear bench supply --there is no substitute in a home lab --those switchers cause more problems than they fix
also put a capacitor on the output of your up convertor to stop it from going into current limit when you start the pump around 10,000uf would be good
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Richard Hull »

I was about to suggest a real "man's" power supply. Gotta' put a 160 watt load at 80 volts in the form of a 40 ohm 300 watt wire wound. Now that is a real supply if it still reads 80 volts across the 40 ohm resistor. Sure you don't need that, but that is the kind of supply and the kind of real test you need to perform. Then you have a man's supply.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Cristiano_Machado »

Hello,

I have one EXT255H, but my controller is EXDC160. I found an old post about the controller and it seems that the manual you are using is for the new model.

My model was an old one, and the post recommended the attached manual. It worked perfectly for my turbo and controller. I use just a 24V power source.
Attachments
EdwardsControllerB.pdf
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EdwardsControllerA.pdf
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

The manual I posted is for EXDC80, part number D396-40-000. This matches the part number and description of the physical unit, and it takes 80V. It has a 9 pin connector.

There are also 24V pumps, and 24V EXDC drive modules, called "EXDC80 24V" etc, which sounds like your system.
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Rex Allers »

Arun,

Maybe I'm not understanding what you describe, but what you said about measuring current makes no sense to me.

You said,
"I measure 0.35A across the + and - leads of the DC power supply."
and
"I measure 80V and 0.98A across the + and - leads of the output of the DC booster."

Are you saying you have an ammeter or a meter set to amps and you are putting the probes across the + and - terminals of your supply and also + and - of the booster output. If so, I don't know why that didn't blow a fuse in the meter or read a lot higher.

An ammeter needs to be in series between one side of the supply and its load. It measures the current flowing in the circuit by having that current pass through the meter on its way to the load. An ammeter has effectively (close to) 0 ohms between its terminals. If you connect it across the output terminals of the supply, you are measuring all the current the supply can give. With a decent supply that may be more than the meter can handle and usually there is a fuse in the meter that will blow.

You said the main supply can make 30V at 5A. If you have it set to 30 V and the current knob is all the way up, then you put an ammeter across the output terminals, the ammeter should read about 5A (unless that's too much for the meter and it blows the meter fuse). While making 5A, the voltage on the supply's meter should drop down near zero.

Does that make sense to you? Did I misunderstand what you did in measuring the current?

Something in your description and/or what you measured doesn't make sense at the level of ohm's and Kirchhoff's laws.
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

Good point. My meter has some kind of short circuit protection, so maybe that was triggered and the value it was reporting was junk.

I have a linear bench DC supply arriving tomorrow.

When I set the meter to max/min mode and measure the voltage on the 80V DC booster when I turn on the 30V switching supply, it reports "OL" meaning over range, however I need to redo this to make sure it is measuring an appropriate voltage range. It is set to autorange on voltage, but maybe autorange does not work in max/min mode. Hopefully it is truly doing a voltage spike on startup which is triggering the pump to go into fault mode, because otherwise I don't know what the problem is.
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Chris Giles »

Hi Arun,

I recommend that you get comfortable with how to measure voltage and current first and experiment with how the voltage and current limit settings work on your PSU(s). You can do this by using some resistors and experimenting with the PSU at low power, say < 10V and < 0.5A. This will be useful for you for other tasks as well.

As Rex points out, if you have put the meter *across* the PSU while measuring current, you have short circuited it! Whilst this will indeed test the current limit it is highly inadvisable especially with a cheap PSU and above a few volts. I don't think you will get any useful information using the DMM in min/max mode. To see the dynamic behaviour one would use a scope but that should not be necessary for this task.

If you tried the Turbo when the PSU was not shorted out, then I suspect that you have not satisfied whatever conditions are necessary to enable the motor drive. Your other measurements make it seem like it is in a standby state.

Regards
Chris
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

The linear DC supply arrived, but the problem remains. Everything is the same.

I will try the 10,000 uF, 100V-rated capacitor when it arrives in 48 hours.

In the meantime, I'll investigate potential issues like oil level.
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Cristiano_Machado »

Hi Arun,

Can you explain how you are wiring the driver? Are you sure you are using the right pins with the correct input?
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

Here is the pinout that I'm doing:
pins-labeled.jpg
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Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Post by Arun Luthra »

I'm pretty sure it's correct, but hopefully is something is wrong and it can be easily corrected.
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