Defective Cartridge heater - Varian 1200 Single-Quadrupol

[oth]

Hello,
the cartridge heaters for the ion source don't last very long and a new board is too expensive for us to replace every couple months.
Does anyone know the specifications for such small cartridge heaters ( there are four small cartridge heaters and one thermistor on the ceramic pcb inside the ion source as can be seen in the photo below)

The device is: Varian 1200 Single-Quadrupol Mass Spectrometry
The part number of such ceramic heater pcb is : ASSY 9300006300



We are thinking about just replacing the defective cartridge heaters myself instead of buying a complete new pcb every time.
The pcb itself is Ok - only the small heaters go defective after some time.

This is a picture of one of the four heater cartridges. As you can see one lead is broken or melted off.



thank you for any help

[Burfict]

Do you see any part numbers or ratings. Varian and others typically go with Watlows. I can possibly get you quote for replacement heater rods. I also have a Varian 1200L triple quad, are these found on the triple quads? If so I can take it off, just give me a price you're willing to pay.

[Jaben]

OTH,

Did you ever find these cartridge heaters? I checked with Bruker and Agilent and neither one of them even carry the Ion Source PCB anymore. I found these cartridge heaters online, and they seem to be the correct diameter and length:
http://www.oemheaters.com/p-5082-18-x-1 ... eater.aspx

Thanks for any help you can offer me.

[Jaben]

Me again. We kept getting cartridge heaters and soldering them onto the pcb, but they would only last like 1 month before they burnt out again. We ended up having to buy a whole new PCB assembly. If anyone needs the whole pcb assembly, you can get them from Belilove Company-Engineers in California. There is a guy there who designed the original PCB for the varian 1200. http://www.belilove.com/

[revengecry]

Normally this item lasts very long. Probably the problem is the board which supply power to this board. Did you checked the voltages?

[Jaben]

Sorry I haven't responded in a long time. We got a new PCB assembly and it worked for awhile, but then the source temperature started fluctuating rapidly, so I thought it may be the thermistor on the board. I sent it back to belilove and they checked it and said that it was fine. I am venting the MS now and will check the voltages going to the PCB. I tried to look in the manual and online but am not sure what the voltages should be. I will try to update today, after I check them. Thanks for the suggestion.

[Peter Apps]

I suspect that you have poor thermal contact between the cartridges and the block - this is why the cartridges overheat. Without re-machinging the block, or finding cartridges that are a tighter fit to the holes this is very difficult to fix. As a workaround, when you start up the MS, increase the setting for the source temperature in 10 C increments. Say the source starts at 40 C when the MS is shut down, increase to 50 C. wait for it to reach 50 C, increase to 60 C, wait for it to reach 60, etc etc. This is slow and tedious, but probably saves time and money compared to replacing cartridges as frequently as you have had to.

Peter

[Jaben]

Thanks Peter! Last night and today I have been working on it. I used the software to check the voltages to the PCB and everything passed, so that is one thing that can be ruled out I guess. However, during this diagnostic test, the filament test failed due to "excessive leakage". From the report this basically looks like the amps going through the filament are much higher than what they should be. I tried using a different filament with the same results. I am a little rusty on my physics, so I am not sure what this means, but could the filament then be receiving current from a route that it is not supposed to be receiving from?

I will try your method of heating up the ion source slowly. Today, the source heated up with minimal temp fluctuation (1-3 degrees C) until about 180 C. After this it still heated but fluctuated by about 5-10 C until it reached 220 C. At 220 C it stabilized for a few minutes and then began decreasing to around 190 C. After this it started its routine of fluctuating from 180-260 C and back to 180 C within a second or two. I don't think the temperature is actually changing this fast of course, but the instrument believes that it is. The source temperature we have used in the past has been 250 C, however, maybe we can get away with a lower source temperature as long as it is stable? Also, do you think the filament issue has any connection to the temperature fluctuations? It seems like something is going on with the thermistor for the temperature reading to appear to fluctuate that fast, but belilove tested it they said it was fine.

[Peter Apps]

For the filament current to be too high it must be getting too much voltage, or be touching something that is bleeding current to earth or another circuit (if a filament sags it can touch its support along its length and reduce resistance). Sudden temperature fluctuations and cooked artridges could also be due to fluctuating voltages - so maybe you have a defective power supply. If you do I am surprised that anything works at all, but perhaps the heaters and filament share a voltage tap that nothing else uses.

Peter

[Jaben]

Thank you so much for your help Peter! I will try to check the power supply today. Will give an update either today or Monday.

[Jaben]

Does anyone have a diagram of the varian 1200L power supply? I see that other people have had similar problems with the power supply: viewtopic.php?f=3&t=22066&p=106480&hilit=ruben#p106480 I am just not really sure how to remove it from the instrument without creating new problems. Haha.