Oh Boy - 475


We seem to be getting attenuator problems in these 4X5 series scopes. I have had my hell with them. So I fixed a 475 that had a bunch of problems, but was working fine and the guy, this guy is a a "metrologist" among other things. He will calibrate it himself and has standards which will be sent in soon to be recertified. We are not fucking around. So we am on the phone after I dropped it off and it was working fine and he was messing with it and heard a "crack" or whatever. Now if you read my group, this is my co-conspirator in test equipment and audio. (this business thing is actually starting to take off a bit)

So there is this noise and now the volts/div spins freely and makes no change, though it seems to work alright at the gain it is at, not sure but I think it is at 500mV/div right now, and it will not change.

Has anyone had these things apart for this and know anything ?

I am a realist and with the frequency at which we have gotten these attenuator problems I can only surmise that replacement assemblies are not going to be easy to get.

Now this is the guy who had open heart surgery, replaced valves n shit, and his house got robbed when he was in the hospital. They stole a bunch of tools and we were going to take it apart when I was there but he didn't have Allen wrenches ! What a trip eh ?

Anyway, what I am looking for here is of anyone has real experience on these attenuators. I have looked and found that for the 475, nothing else will fit. Actually the part form a 465B might fit a 475A, but not this. It is not an "A". For the normal 475 there are more tits on the cam that actuate the low v/div range. The 475A does not have that, the 465b assembly might work if he wants to give up that extreme sensitivity.

But has anyone worked on the mechanics of this ? I am just assuming at the moment that the parts broken are nylon, which is almost impossible to glue. My Mother is a bit of an expert on this and after what she told me I decided to do something else last time I needed to glue nylon. I can pin it, drill and insert a hot paper clip and all kinds of things, but I have never even had that part of these things apart before.

So I am looking for a little advice on how to approach this. Not only does the knob turn freely, and I am sure it is not loose Allen screws, but it seems to move back and forth easily, as if it is broke off any bearing type of things it may have had.

I'm all ears, and I got alot of time into that thing. It had like five problems when it showed up. I fixed them all but now this comes up and now what, a one channel scope ? And that is no good because he wants to give it to someone.

If I can't get a crack at this soon I might take apart the 465B I got, actually for fixing that one. It has to be similar. What's more, I did mess with the channel 1 attenuator but now there is no problem with that. It is channel 2.

Don't get the idea I am bitching or sh\whining about this, shit happens. More shit happens when the equipment is old enough to drink.

I might soon be sorry I sold my lathes and milling machine. Then I will bitch and whine...

Ideas ? Thanks.

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