Chromatography Forum

Hi. I have contacted the service provider on this issue. However, I have not received a reply as yet and was wondering whether any of you know what has happened here.

The ECD base signal was way high and the maintenance manual suggested cleaning the collecting electrode.

I followed the instructions which indicated to signal, excitation and heater signals. After disconnecting the heater signals the temp went to 625 or somewhere about that and the instrument indicated that the temp was way above the working limit and shut down.

So I reconnected everything only to find the temperatures from the oven, inlets etc are not regulating they are at -273.

In general it is VERY good practise to switch everything off before you start disconnecting anything.

Disconnecting the temperature sensor (which is probably a resistance thermometer) made the instrument think that the sensor had broken, and it shut itself down to avoid overheating the detector. Since many instruments have all their heater controls on one board this has also possibly upset the controllers for the other heated zones. Try switching off at the mains and switching on again, and shut down the software and re-start. There may also be a specific re-set, or error clear button that you need to press.

Peter

-273 is absolute zero and is usually the sensor reading you get when there is no resistance (IE, open circuit or board not controlling temperature/sensor, or etc..)

It sounds like you either have hooked something back up incorrectly, or something may have damaged the temperature control.

What kind of GC is this?

When you cleaned the ECD you didn't actually take the anode out or touch it or anything did you? Bending the anode would be very bad.

Thanks Peter. What you say makes much sense. I did shut down and reboot. Unfortunately nothing has changed.

It is a Thermo GC Ultra. I do not think that I did anything to the anode. The directions only went as far as the collecting electrode.

With I Termo does not work, but common approaches are the same.
What ails ? Please describe how events unfolded.

What caused the need for cleaning the collector?
Display indicate Injector temperature and the Heater temperature 625 (or -273) adjusted to parse the detector or the after parse detector?
The device was turned off when cleaning the collector?
Ultra has an keyboard? Take a guide? and try step buy step , read manual (operator instruction) book, set the temperature of the injector and the heater. How device reactions? What displayed on the display (error codes)?
Preliminary diagnosis of Peter Alps high probability.

PS Not be ruled out bad option parsing enabled device.
"KZ-HZ"? [ abbreviation "Short-circuit-(untranslatable expletive) knows"?]

@aldehyde: On the contrary, -273°C means a short circuit.

As some heated zones show this behavior, I'd say that either the temperature controller is fried or you made quite a mistake reconnecting the ECD (like giving a floating mass to the temp. controller).

At first I'd try a complete reset of the unit.

If this fails, power off the unit and disconnect the ECD. Then power it up again and check if the temperature readings for the other zones are correct. If this is not the case, you did damage a part of the electronics.

From my experience the Thermo GCs (being in essence little improved Carlo Erba/Fisons instruments) are at best second-class instruments with horrible, very sensitive and easy-to-break electronics.

Thanks for your advice HbJ. Since you have experience in these equipment and I do not. I am asking exactly how you advice I should reset the unit.

My personal experience with Thermo/Fisons GCs ends with the 8000 lineup which was more than enough to cure me from them totally. But I heard on conferences how much some fellow colleagues suffer from the GC Ultra.

A reset would be made by switching the unit off, waiting for 30 seconds and powering it on again.

The questions are: What zones show -273°C and what are the readings if you power off the instrument, disconnect the ECD and power on the instrument again?

I did that reset and nothing happened. Unfortunately I also did the disconnect from the ECD and nothing changed.

Yes I have heard about others having problems with Thermo instruments.

The oven and injectors are showing -273. The ECD is reading 40. I have no control of the temperature though.

So all zones are at -273 now?

Basically yes, except as I said the ECD temp (or base temp). The instrument is off right now.

I have contacted the service providers and they indicated that the problem is most likely the motherboard. They have no physically checked the unit. Additionally, they are saying that the only option is to replace the motherboard before any other troubleshooting can be done.

I am just wondering if there are any other options out there. E.g. could they check the board and replace components, instead of replacing the entire board and then check to see any other problems?

As some of your suggested the problem should be the power supply and not the motherboard. The local thermo representatives are now agreeing that it may be the power supply. However, they are willing to check the unit to isolate the problem.

Will keep the board posted.

The service technician is here. He saw a blown fuse on the power supply. (position F1). He changed fuse but nothing has changed.
He says that the power supply board looks ok.

Any ideas?