Tektronix 475 repair question

[kanakun]

I have a Tektronkix 475 that i purchased but the only way i can get a trace to show up is the a inten setting I don't believe this is normal from what i have seen with other scopes. I don't know where to start with trying to repair this so I came here to ask for help.
tia, Nathan

[Wallace Gasiewicz]

Manual is here :   https://download.tek.com/manual/475Service.pdf
I have one, it was in its time a very good scope and cost as much as an automobile.

Look at the Table of Contents
Go to the Operating Instructions and then Obtaining Basic Displays

See if that is any help, let us know

[Uunoctium]

weird trigger settings i.e. wrong channel, slope? Could lead to an blanked or darkended trace

added:
in which position is your timebase knob? Coupled or delayed position? If i remember right, the 'A Int' works only on second.

[MathWizard]

If you know the safety basics, start checking the various rail and test point voltages. IDK about the high voltages on these tho, so be careful, I wouldn't probe much of anything in the HV section. IDK how long those circuits would take to be safe after being powered off either.

[kanakun]

I finally got A-Lock-Knobs working occasionally but any adjustment often just makes the trace disappear. also i noticed after running the scope for a few minutes it destabilizes and I'm no longer able to get it to stabilize on the 30ma calibrator pin with any of the horizontal display settings and it just jumps around weirdly.

If you know the safety basics, start checking the various rail and test point voltages. IDK about the high voltages on these tho, so be careful, I wouldn't probe much of anything in the HV section. IDK how long those circuits would take to be safe after being powered off either.

Thanks for this advise, I'll try doing it this weekend if I have the time to but I guess for the time being I guess I don't have a very functional oscilloscope

[George Edmonds]

Hi

Looks like you need to replace the power supply electrolytic capacitors, a standard problem with 475's

G Edmonds

[dietert1]

On german ebay there has been a clean and working 485 already for some weeks, looking for a good home. A 350 MHz scope at € 440.
I remember fixing one of those as a student. There was a thick printed manual and it was a minor fault. At the time i was impressed by those gold plated circuit boards and the integrated high bandwidth amplifiers with separate pins for external RF terminators and feedback networks.
Of course nowadays everybody prefers a DSO with color screen.

Regards, Dieter