Eico 460 Oscilloscope

[Findm-Keepm]

Originally Posted by darklife

Thanks for the replies so far. I will look around my junk boxes and see if I can find an old transformer that will work as a "bucking transformer". I just don't feel comfortable with how warm the power transformer runs but I don't know maybe it was made to handle that much heat. It gets almost too hot to touch after an hour of operation while inside the cabinet.

Another problem I notice is that on a few of the sweep selector ranges the waveform gets more narrow toward the left of the CRT, and wider toward the right. Just enough to be noticeable to the eye. I wonder if the sweep oscillator needs a tuneup or maybe has an old capacitor that is acting funny?
It only seems to happen on the 1-10k range.

I don't really have any other projects going for me right now so I plan on tinkering around with this until it works really good. Do a few modifications to make it run better and recap it so it runs as new. Besides this is teaching me a lot about the internals of how an oscilloscope operates so it's an educational project for me.

Any further ideas or suggestions are appreciated.

There are thousands of these out there working on the higher line voltage with no problems. Definitely do the recap - the B+ filter caps, even with the slightest leakage could cause the tranny to get hot. Even a few milliamps of leakage at 375 Volts could equal several watts. I fired off my 460 this afternoon - it hasn't run in about a year and a half, and it woke up fine. The tranny was barely warm after 20 minutes. I put her back together a hour or so later, and the tranny was just warm, not hot. I'd replace the 20/20/20 @450 with some 22uF@450 caps and see if that cools it down some.


Cheers,