When i start my pc then i get horizontal line regularly

I found an article with steps you can take to troubleshoot printer issues:
http://www.castleink.com/category/288/Fix-gaps-in-printout-horizontal-and-vertical-lines-Video.html

Still, have issues with your printer call me out at 1800-204-4427. I can solve you out via phone.

No PC model stated
no OS stated (opr. system) windows 10?
we can not help you, ever lacking key facts
why not go to your HP support page and load all software
Related to Laserjet 3050

here

https://support.hp.com/us-en/drivers/selfservice/hp-laserjet-3050-all-in-one-printer/1140783/model/1140778

Regularly spaced horizontal lines suggest that there is a defect on the drum in the printer. I would suggest changing the drum to see if that will fix the problem.

I am sorry but, usually, that is the start of the screen's LCD failing, it will most likely get worse over time... This is caused by the "Driver" transistors failing....

Incedible in one web page I found this solution and its work for me, the problem is the batery, just remove and no more frezee screnss and horizontal lines in color purple, Hope this helpt to you.

Horizontal may not be due to the CCD sensor. It can be due to the lens itself. I swap lens from a non-working camera to replace the one with horizontal lines. I found out that I was able to get the camera to work to take great pictures.

chk vertical amp /vertical drive i/p from oscillator/power to it/power to vertical amp/chk dry joints-hot area/look at vertcal amp capacitors-swelling etc

Most likely a bad Vertical IC or bad connections on the vertical IC. don't continue trying it on. If you have a bad connection it could do more damage. You also could damage the CRT ( picture tube ). If you remove the cover and look at the bottom side of the PC bord with a good magnifiing glass you may see what looks like rings around the leads comming from the Vertical IC. The Vertical IC is mounted on a heat sink usually towards the front of the set looking from back. If you do see the rings around the leads try reheating with a solder iron. If this dosen't fix you most likely need a new IC.

Max is 256M Memory. You're much better off getting a new system. A new motherboard, processor and ram isn't that much...

try to adjust the screen control in the flyback transformer. good luck