Oscilloscope repair

[zachtheterrible]

I just ordered the caps today, so I'll let y'all know how everything goes. and I did figure out how to get the case off right after I made the first post :lol:

 

[Ol Tec]

Hung Chang Cathode Ray Oscilloscope

Hi everyone, first for me so Ill get right down to it.... Got a cro (Hung Chang 6502) lost the trace beam. Supply seems to deliver the right volts around the place, but without ye ol circuit too hard to trace fault with failing eye's. Anyone have a circuit by chance, the same fault diagnosis would even do for another brand, probably the same outcome anyways. Thought of the blanking and trigger networks, but just not enough info on the pcb overlay. There was a chap looking for the same fault with the same brand cro a few months ago, though I can't seem to trace his success in the other forums.... any ideas would be appreciated.....

 

[Leftyretro]

Hustler got it right. That is one jem of a scope and well worth the effort to repair, certainly because so much is working, high voltage, CRT tube, etc. I'm sure it's most likely a cap or a rectifier diode.

Here is a link to a few 475 manuals for free downloading. Not the A model but probably useful for basic power supply troubleshooting.

https://bama.edebris.com/manuals/tek/475/

 

[whiz115]

An ESR meter measures the impedance (NOT the resistance) of the capacitor at 100KHz.

@Nigel impedance is the resistance in AC.


@zachtheterrible good luck with your oscilloscope

 

[Hero999]

Impedance isn different to resistance, energy can't be dissipated in a purely capacitive or inductive load it can only be disipated in a resistive load.

 

[Leftyretro]

Reactance (L or C or both), impedance and resistance are the terms we should be defining and using.

Lefty

 

[atferrari]

Please delete this post.

 

[large_ghostman]

there is a HP yahoo group and they are great realy helpful and friendly! goto yahoo and search the groups they ask a simple question before you get accepted to stop spammers we are members and they have helped alot

 

[bountyhunter]

Impedance isn different to resistance, energy can't be dissipated in a purely capacitive or inductive load it can only be disipated in a resistive load.

Best way to get true ESR is to use a network analyzer that measures impedance as you sweep the frequency upwards.... at some point the impedance goes to the minimum and starts back upwards at the so-called "resonant frequency" where the inductive component and capacitive component are equal. The impedance at the resonant frequency is the ESR.

 

[ectt]

not sure work for oscilloscope or not,
any IC controlled the sweep (h-syn, v-syn in monitor part)