Sm125 only one white line.

[Jpnl]

Hi all,

I found a atari 1040st with included sm125 monitor. The st it self works fine on a TV but the monitor only shows one horizontal white line when the st is turned on. I found some had the problem with a sm124 monitor but did not found a post about a sm125 monitor.

As I never tried to repair a crt before I would really like some pointers in what to check and replace.

I did check the fuses as that would be a easy fix. They where still fine.

If you need more info please ask.
Thanks in advance for your help!

Jp

[mpattonm]

This should help your troubleshooting: http://www.atarimania.com/documents/Ata ... Manual.pdf

[tzok]

the monitor only shows one horizontal white line when the st is turned on.

So it means a problem with a vertical (the low frequency one) beam deflection circuit.

[trashwolf]

Also, to make sure the phosphor doesn't get burnt out, try to keep the brightness very low until it's fixed.

Some general ideas of what to investigate are here (not specific to this monitor): https://www.repairfaq.org/samnew/tvfaq/tvsinghli.htm