Chromatography Forum

Channel cards have to be handled with particular care when removed from the instrument; they are easily damaged by static electricity - at levels you would not notice traveling though your body.

The appropriate switch settings are known at LECO.

After 2 month back to work a week ago. Still stucked with flat profile and no peak for PFTBA. A close look at the channel board shows there are two dip switch and one jumper. I have posted a picture of them here. Could someone please confirm if they have the correct setting? I want to be sure they have the correct settings and not played with by previous people.



I also have following questions:

1- If you disconnect the golden connector of detector cable from the channel board and run optimization what type of profile do you expect? Flat line? If so what would be the number written on the vertical axis? Is it 1064900?

2- When I run optimisation to see PFTBA peak I see 1636800 number at the zero of my profile vertical axis with a flat line and no peak at all (attached photo). When do I suppose to see 1064900?

Finally I managed to repair our channel board. Also I have to replace MCP plates of detector since I noticed they are cracked due to sitting in air for a long time. After these I saw mass 69 peak of PFTBA start appearing at about -1850 detector voltage. Noise level was at 35000 and mass 69 peak at 37000 (only 2000 count above noise). I got below 100 signal/noise or lower depending on detector voltage. I tried to adjust channel board gain and offset through priority diagnose screen. At itr control menu I clicked on automatic adjust while I choosed both gain and offset. All I saw software went through decreasing offset from 400 downward and drawing profile after each decrease in offset. This happens when I choose both offset and gain. Surprisingly gain never changes and stays on 500 all the time even when I choose gain to adjust. I did manual change of offset and gain and clicked on start profile but no use. Now I don't see even that small peak of mass 69 when I do optimization. I lost mass 69 peak. All I see noise at about 35000 count at all masses. I don't know what happened. Did I screwed up my gain and offset adjustments?

I can do a fresh Chromatof software installation but I am not sure this will solve the problem. I need step by step instruction of how to do main gain and offset adjustment. I am using windows xp professional.

I am really stuck here and need help from anyone who can help.

With new detector plates, you should get a good signal at aobut -1400 V. At -1850 is an indication that you are working inthe right direction, but you do not want to have to run te instrument at that voltage.

Now that you have access to the advanced diagnostics, you have done everythign that I remember to do for adjusting gain and offset. I don't expect to see much change until the offset is adjusted. The noise level is still much too high. Some of the older manuals have instructions for turning potentiometers for adjusting gain and offset -- this is for an older model instrument. Theses potentiometers are not on the model that allows for adjustment throught the software.

With new detector plates, you should get a good signal at aobut -1400 V. At -1850 is an indication that you are working inthe right direction, but you do not want to have to run te instrument at that voltage.

Now that you have access to the advanced diagnostics, you have done everythign that I remember to do for adjusting gain and offset. I don't expect to see much change until the offset is adjusted. The noise level is still much too high. Some of the older manuals have instructions for turning potentiometers for adjusting gain and offset -- this is for an older model instrument. Theses potentiometers are not on the model that allows for adjustment throught the software.

My Chromatof is 2.0. Pegasus driver version 2.11. Manual says so too but potentiometers manual refers to are not there. I will need a copy of the new version of the manual or at least those pages which are different. Specially pages explaining how to adjust offset and gain. I sent you an email to send me those pages if you have it.

I found myself how to do the offset and gain adjustment with our Chromatof 2.11. I have another problem now. I have no fault at first when Chromatof starts on the diagnostic screen but when I click on "optimize now" I get fault check mark in front of "Z Deflection" (its value is about 3 volts - see attachment). I checked and realized Pulser Board is the problem. Its output signal seems not correct. I took out this board and fault is went away but now seem I have all the peaks (including unwanted peaks - see attachment) and no deflection. My question is what are all those extra peaks around mass 69 of PFTBA peak?

I am also looking for the PDF of the newer versions of the pegasus III manuals since LECO shipped the instrument with an older uncomatible and wrong manaul version.

Any idea?

Anyone by any chance has electronic schematic for the "low noise pulser board"?

I really need it.