HP 1727A scope revisited; vertical amplifier problems.

[Alex_Baker]

Thanks, don't know how my search didn't find that.

[CaptDon]

Looking at the trace you have zero crossing distortion which indicates generally not enough bias on the deflection transistors so they only conduct in areas above the zero crossing area. I know you have done some troubleshooting. I would be looking at resistors that have gone up in value and often in the deflection circuits that resemble comp/sym you have to check everything 'out of circuit' and look for shifts like an 18K measuring 22K out of circuit. I have seen that and been fooled by 'in circuit' measurements where the values look spot on!!

[Alex_Baker]

Thanks for the info, however on a different HP/Agilent specific site we did some troubleshooting that showed that U2 is bad, resistance measurements between pins of an otherwise symmetrical IC are not symmetrical.

[guneszop]

I think the next thing to do is check the voltages on U1 as appearing on the schematic techzpod.com mobdro apk
 

[Alex_Baker]

I think the next thing to do is check the voltages on U1 as appearing on the schematic

Please review previous posts.