Plasma goes on for few seconds then switches off

Question

We have a 7800 ICPMS and was working fine until this morning I switched the plasma on and it went on then off in a couple of seconds. 
 
 The RefPower goes up from 0 to about 170 and the Forward power up to 1198 then it switched off. 
 
 I removed the shield plate: RefPower went up to 209, Forward power went up to 1198 again and switched off. 
 
 I put the shield plate back on: RefPower moved from 0,110,484,2268,167,0. Forward power moved 0,749,200,181,0 then it switched off.

Efstathios.Sianos · Answer

Hi Qiqa, if the error you are seeing is "Plasma did not come on" but you are indeed seeing the plasma on for 2-3 seconds then your fiber optic cable is either dirty, broken or pulled back. Check in the middle of your torch stand, you should see there the end of a black fiber optic cable. Pull it out from the back, cut 5mm, remove 1-2 mm the black insulation at the end of the fiber and re install it. In the middle of the torch stand you should see the "naked" 1-2mm of the fiber optic. Then please try again. As I said in the beginning, also important is the error you are getting.