Chromatography Forum

I am told I need to disassemble the analyzer, and check the electrical continuity of the filaments in my 5970. I have no maintenance manual for this unit; any chance anyone can give me a synopsis of the procedure?

I am told I need to disassemble the analyzer, and check the electrical continuity of the filaments in my 5970. I have no maintenance manual for this unit; any chance anyone can give me a synopsis of the procedure?

Seek advice from James:

viewtopic.php?f=3&t=21108&start=7

You should not need to disassemble the analyzer, continuity can be checked while it is still under vacuum. If I remember correctly, you have to remove the cover on the end of the analyzer and you will see a circuit board there. You should find a test point or solder point labeled FIL1 or FIL2, actually should be two of each. You can put the multimeter probe on those matching points and if you get continuity the filament is good. Also do a check where you put one probe on the test point and one on the chassis somewhere, if you get continuity there then you have a short to ground.

Oh and turn off the switch for the electronics before removing the end cover. The 5970s should have a switch for electronics and one for vacuum, which I wish the newer models had also.

I couldn't find a pic of the circuit board but can point out the cover to remove from this one.

http://www.stolaf.edu/people/jackson/gc ... ogcms.html

Third photo down, on the far left you see the silver end of the analyzer, then tan vented cover on the end with the connector on top. Remove the top connector, then if you look between the end of the analyzer and the body of the MS you will see the screws that hold the cover on. You will need a 90 degree phillips head screwdriver to get to them with the analyzer still installed.

Found a photo of the analyzer from the inside.

http://www.kitmondo.com/hp-hp-5970-ms-2/ref157113

In the lower left of that photo, there is a circle of solder points, the filament test points should be there, look for that circle on the outside of the board if you test with the analyzer still in the instrument.

Found the test points- the case on the analyzer is different (six screws, three each in two rows, all on the outside so no funky driver required), but the guts are the same.

Filament 1 reads 0.000 ohms, but filament 2 reads 0.527 ohms- consistently. Tested each half a dozen times, just to make certain. Neither shorts to chassis.

Filament 1 is good, and #2 is... on its way out, or thoroughly shot?

...
Filament 1 reads 0.000 ohms, but filament 2 reads 0.527 ohms- consistently. Tested each half a dozen times, just to make certain. Neither shorts to chassis.
Filament 1 is good, and #2 is... on its way out, or thoroughly shot?

If your measurements are really so accurate then I bed filament 1 is shortcircuited or you measured a resistance of heating circuit (and even if the filament is burnt out you would get 0 ohms).

In fact you should measure the resistance of a filament isolated from it's circuit.

...
Filament 1 reads 0.000 ohms, but filament 2 reads 0.527 ohms- consistently. Tested each half a dozen times, just to make certain. Neither shorts to chassis.
Filament 1 is good, and #2 is... on its way out, or thoroughly shot?

If your measurements are really so accurate then I bed filament 1 is shortcircuited or you measured a resistance of heating circuit (and even if the filament is burnt out you would get 0 ohms).

In fact you should measure the resistance of a filament isolated from it's circuit.

There could be a little bit of dirt at the contact points of the #2 where the screws hold it on, but that resistance is still very low, showing that you have current flow through the circuit. If the filament is broken you would have a maxed out ohm reading just as you have when measuring to chassis ground. That circuit measures the current from that pin, through gold foil leads up to the filament, then through the filament and back. It should give very very little resistance so those readings should be ok.

osp001

The readings show that both filaments should be working. Can you tell us what the problem is that would require checking the continuity or are you just making sure it is assembled correctly before running it?

OK- quick re-do, this time metering for resistance instead of diode check. Dummy me.

With the switch set to "Filament 1," I get 0.5-0.6 ohms across the solder connections for filament 1, and 1001 ohms for filament 2.

Switched to "Filament 2," I get about 0.9 ohms for filament 1, and 1001 ohms for filament 2.

The difference in filament 1 is probably due to the inability to get an ideal contact on those old solder joints.

So- in this instance, would either filament be bad?

As for why I'm doing all this- I am getting some wonky readings, trying to get this old MS back in service.

When I autotune (long or short), I get "Cannot achieve constant peak widths" to "Fault Status 2" to "gain and offset = 0 and peaks are too narrow".

With manual tune, I get

With autotune, I get "Tune error- there is not enough signal to begin the tune".

I get the same with both front and back filaments.

There IS PFTBA in the vial.

I was advised to dip the coils, and got the following:

RFPA = 10, voltage 0.011 VDC
RFPA = 100, voltage 0.044 VDC
RFPA = 300, voltage 0.118 VDC
RFPA = 600, voltage 0.240 VDC

I did the above at my mentor's recommendation. My suspicion is that the electron multiplier is dead, but he didn't think this was necessarily the case. However, my mentor has since disappeared, and I've been trying to snoop out what's wrong ever since.

OK- quick re-do, this time metering for resistance instead of diode check. Dummy me.

With the switch set to "Filament 1," I get 0.5-0.6 ohms across the solder connections for filament 1, and 1001 ohms for filament 2.

Switched to "Filament 2," I get about 0.9 ohms for filament 1, and 1001 ohms for filament 2.

The difference in filament 1 is probably due to the inability to get an ideal contact on those old solder joints.

So- in this instance, would either filament be bad?

As for why I'm doing all this- I am getting some wonky readings, trying to get this old MS back in service.

When I autotune (long or short), I get "Cannot achieve constant peak widths" to "Fault Status 2" to "gain and offset = 0 and peaks are too narrow".

With manual tune, I get

With autotune, I get "Tune error- there is not enough signal to begin the tune".

I get the same with both front and back filaments.

There IS PFTBA in the vial.

I was advised to dip the coils, and got the following:

RFPA = 10, voltage 0.011 VDC
RFPA = 100, voltage 0.044 VDC
RFPA = 300, voltage 0.118 VDC
RFPA = 600, voltage 0.240 VDC

I did the above at my mentor's recommendation. My suspicion is that the electron multiplier is dead, but he didn't think this was necessarily the case. However, my mentor has since disappeared, and I've been trying to snoop out what's wrong ever since.

Is it still running the old Galileo multiplier horn or has it been upgraded to the newer K&M style(white and gold ceramic type)?

Was it sitting at atmospheric pressure for any length of time when not in use? If so that will pretty much kill a Galileo multiplier and isn't good for the other types either.

The abundance you are getting is more or less electronic noise, so it could be either bad filaments or bad multiplier. The RFPA voltages look good so I would think you are ok there.(if memory serves me, not so certain about that any more)

Phew. OK- after installing a new multiplier and pumping it down overnight with the electronics on, I occasionally get lucid moments like this:



But they are invariably followed by:



I take it I should just pump it down longer?

Also, the recommendation from the manufacturer is to start with low voltage on the multiplier, and work your way up, lest you cause damage. Is "autotune" sufficient, or should I be setting voltage parameters manually?

While the system is pumping down, should I be running carrier gas (hydrogen), or should I cut it, so long as the GC is off and cool?

Phew. OK- after installing a new multiplier and pumping it down overnight with the electronics on, I occasionally get lucid moments like this:



But they are invariably followed by:



I take it I should just pump it down longer?

Also, the recommendation from the manufacturer is to start with low voltage on the multiplier, and work your way up, lest you cause damage. Is "autotune" sufficient, or should I be setting voltage parameters manually?

While the system is pumping down, should I be running carrier gas (hydrogen), or should I cut it, so long as the GC is off and cool?

Carrier gas flow is ok while pumping down. Overnight should be sufficient to remove most of the air and water from the analyzer since the analyzer chamber is heated on a 5970.

What multiplier voltage is being used for those screen shots?

Also what type of multiplier did you put in it?

Carrier gas flow is ok while pumping down. Overnight should be sufficient to remove most of the air and water from the analyzer since the analyzer chamber is heated on a 5970.

What multiplier voltage is being used for those screen shots?

Also what type of multiplier did you put in it?

Voltage originally started at 1200 and ramped up, so (based on the multipler's manufacturer recommendations) I went to starting at 200, then 400, etc. and- after a few cycles with no success, allowed the MS to attempt to autotune at the voltage of its choice- mostly in the 1400-1600 volt range, but occasionally straying above 2,000 before giving the error message.

The multiplier is a DeTech 2300KM, as this is one of those oddball 5970s with a 5971 detector.

Carrier gas flow is ok while pumping down. Overnight should be sufficient to remove most of the air and water from the analyzer since the analyzer chamber is heated on a 5970.

What multiplier voltage is being used for those screen shots?

Also what type of multiplier did you put in it?

Voltage originally started at 1200 and ramped up, so (based on the multipler's manufacturer recommendations) I went to starting at 200, then 400, etc. and- after a few cycles with no success, allowed the MS to attempt to autotune at the voltage of its choice- mostly in the 1400-1600 volt range, but occasionally straying above 2,000 before giving the error message.

The multiplier is a DeTech 2300KM, as this is one of those oddball 5970s with a 5971 detector.

Sounds like it had been upgraded somewhere along the line to the newer style multiplier. Those are normally good multipliers and much more rugged than the original Galileo units.

Have you gone into manual tune and run a full scan to see if there are any ions showing up at all? If the mass axis is off by more than 5-10 units the autotune may not be able to find anything to use for alignment. Also if you have the opaque white vial for the tuning liquid(PFTBA) make sure there is still liquid in it, I have thought before something was wrong but it was just that the vial was empty and didn't know it because unlike the glass vial on the 5971 I could not see the level. If it is just that no PFTBA is getting into the analyzer you should still be able to see some air and water at mass 18, 28, 32 and 44.

With the reflection I can't really see the abundance of that one peak you are getting around m/z 65, is it only a few hundred counts or is it more?

Your filaments are fine. You should get a finite (non-zero) but low reading off of filaments.

This is not an EM issue. I'd guess that you're looking at an A14 (RFPA) problem, but you need to find out.

In diagnostics try to get the RFPA to scan to 800. I'm guessing that it won't, but try it. Start the quads at a mass of 10 and move up in units of 100.

If you can set the RFPA to pass 800 then your problem is probably on the A5 board.

I have a manual for the 5970 as well as multiple of each of the boards. Happy to help you try to troubleshoot this. The one thing we don't have are spare Schottky diodes; hopefully that is not the problem here.

If you'll send me your e-mail address I'll copy the manual and e-mail it to you.

BTW, the 5970 is easily as sensitive as the 5972 if you run it correctly.

Mark Krause

Well, I had a pro come out this past week and poke around; after a lot of hemming and hawing, he re-checked the filaments, and got 1001 ohms on both of them. I opened it up that night, and found both filaments were fried. So, new filaments are on order, along with a ball-end hex driver to get into that nasty space in the block to replace them.

I have been searching for a manual... forever. I have been told they were fairly ephemeral, given the changes along the lines, but a .pdf would be fantastic: osp001@hotmail.com, please and thank you.

Hopefully new filaments will get this 5970 back into service- fingers crossed and all.

All right- new filaments in (and for anyone reading this in the future, a ball-end hex screwdriver, a 0.05" / 1.3 mm, Wiha part number 264 or maybe 26413, is indispensible for this task), under vacuum with the roughing pump for 36 hours and then warmed up for 8 hours with the turbo pump on... and I finally got a tune. Bliss. I didn't mess with it too much, and then turned off the turbo pump and the electronics. I left the roughing pump on.

I came back to it after about a week- still under vacuum, let it warm up for several hours with the turbo pump on, and I couldn't get a tune. Repeated the procedure tonight, with the same results:

"There is no emission current."

"Tune error: MS status fault 8"

The Instrument Control page says "EM Volts 0" and I can't seem to change that. I have it set for about 1108 volts elsewhere (I can't seem to get it to take a different voltage), but can't get it to change on the Instrument Control screen.

I re-checked the continuity of both filaments: 0.6 ohms on each filament.

What am I doing wrong?