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Electronics => Repair => Topic started by: jonsikul on April 24, 2024, 07:04:41 pm

Title: HP 8566B CRT focus problem
Post by: jonsikul on April 24, 2024, 07:04:41 pm

As the title suggests, I am having a problem focusing the CRT on my HP 8566B. When adjusting the focus on the front panel it is like I just need a half a rotation more and then it would focus but the focus screw doesn't allow for that.
Is the CRT just weak?
I just got this machine from an auction without any description on how it works, so I am turning it on for the first time.

Title: Re: HP 8566B CRT focus problem
Post by: Greybeard on April 25, 2024, 07:15:19 am

Check all voltages at the CRT.
Check resistance of all resistors and potentiometer in the focus resistor chain and check solder joints.

May be this helps:
https://www.jvgavila.com/hp8566a.htm (https://www.jvgavila.com/hp8566a.htm)