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Function generator problem

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large_ghostman

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Hi, I have a function generator, a basic one that is kind of my work horse, its always the the one I use with new experiments first, mainly because its the cheapest and oldest I have, so I dont have to panic about blowing up dads £1,500 HP one :D.
its been really good but lately I have noticed a problem. Mainly on sign wave it has gone from a really nice smooth waveform, to a stepped one, its still sign shaped but i can see ladder steps in it, they are getting more pronounced and clearer to see.
Am I right in thinking its probably a smoothing cap? I cant get a pic of it for a day or so. I would like to get it back in fighting order tho, as dad sweats every time I reach for the HP:rolleyes::rolleyes:
 
What are you using to look at the waveform?
A digital scope?
Depending on the settings, a digital scope can display a stepped waveform. My HP digital scope often does this.
Have a look with an analogue scope if you have one available.

JimB
 
If its not the scope then I would say a cap is drying out.
How old is it?
 
No idea of age but its getting on :D, I used a digital scope, but I use this FG alot and the steps are far worse than they were. Normally I can zoom right in on the wave and barely see steps.
I have a feeling its a cap, tomorrow I get the screwdriver out :D
 
The value of the smoothing capacitor (or the cutoff frequency of the lowpass filter) must change as the frequency is changed so that high output frequencies are not attenuated..
Maybe the circuit that changes the value of the capacitor or filter is "stuck".
 
That is what we call mums price! The real price was alot higher, so no you cant use it!
"Mums price" Gotta love it.

Be honest, everyone, don't we all make use of this particular accounting procedure...:woot:.

LG, just curious: how does your FG produce its output sig (analog vs. digital)?l
 
he is at school, I think the FG he is on about is his old phillips one, looking at the scope i would say it has a dac in it, i know before the sign wave was very smooth, but now you can clearly see the DAC steps on the trace. This FG is the one that gets all the abuse lol,
I dont like him playing with the HP EGS. Although i will probably sell it.
my worst fear is that when i die the wife will sell my things for what i told her they were worth!
 
The symptoms do give the impression of a cap giving up the ghost :rolleyes:...
 
To me lg getting on a bit would mean it has glass things inside that glow red.

Did you get the octipus to work?, might be handy finding a dead cap with it.
 
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