Hej!
First: this forum is a great information resource, thanks for that!
Also, this is my first post here, so please have a bit of patience with me
I bought a Tektronix 465 for a very good price on the local craigslist equivalent, and I am absolutely in love with it. The tactile knobs, the whole buildquality... amazing. It even came with the tek scope mobile!
After a frantic unpacking of the giant package I plugged it in and pulled the power knob, and tada, we got two traces!
A huge sigh of relief was expressed, as the pictures on the offer were not really good and detailed.
But then a (hopefully) small problem became obvious: Without the 20mhz bandwidth limiter on, the roofs of the calibration square wave are really fat and fuzzy. This happens on both channels. I am attaching some pictures below. With the limiter pulled/activated the signal is very clean and I get a sharp trace.
I know that big bandwidth might bring some noise, but I don´t think that this amount of noise is normal.
(sorry for the picture quality, I only had my smartphone on hand)
I opened it up (after careful reading of the Users Manual) and measured the Voltage testpoints for +55, +15, +5, -8 and +110 V. All of these were right in spec, only 110v was on the upper scale of the limit.
While the scope was open, I also did a thorough visual inspection, and found some gunk around the bases of the big silver caps behind the trigger circuit board, but I am not sure if it is leakage (the board beneath looks fine) or if it´s just flux. Does anybody know?
I am pretty new to the oscilloscope game, and so I decided to ask my questions here:
Where would one start to check/test to maybe fix this issue? Is it an issue? What might cause the problem? Might a normal calibration fix it or is it more likely to be an ill-aged part (like the silver caps)? If the voltages are in spec, does a ripple measurement make sense? I do have access to a digital Oscilloscope, so that would be an option.
That are a lot questions, but maybe someone here had similar problems. I would really love to get the scope working completely.
Thanks in advance, and sorry for the long post
Cheers,
Timo
Oh and P.S.: is there a serial number anywhere inside the device? The one from the front panel is missing on my unit...