Re: Difference between a 475 and a 475A


 

John Gord wrote:

My unresearched recollection is that the 475A was basically the same as the 475, but adjusted for higher bandwidth but
perhaps slightly inferior pulse response. The 475A lacked the 2mV/div vertical setting.
Cool. That's something that I can verify! The scope whose faceplate reads "475A" does indeed lack a 2mV range (and it has a 100V range, which the 475s lack). That means that I should be able to see a difference in the cams for the vertical range switches (same number of cam positions, but they should engage different sets of attenuator blocks, or the blocks should have different values).

If the 475A were working better I could also check the pulse response, as I acquired the tools to do that measurement while evaluating my father's scope a few months ago. I'll be checking the pulse response of the both of these scopes under any circumstance, once I've repaired whatever is wrong with the 475A, just so I know what parts are good candidates as spares.

I suppose that this would also mean that, if you had swapped the front panel and knobs from a 475 onto the innards of a 475A, the V/div would be wrong (everything would be off by one position). That should be easy to verify on the suspect 475 (except that the V/div knob skirt is basically illegible from whatever is spattered all over the poor scope).

Any advice on what kinds of solvents are reasonable to use on the front panel and knobs of a 475?

I've tried both of the suggested cleaning agents -- detergent with water and isopropyl alcohol -- to no effect on this scope. I'd like to clean up some of the surviving knobs and skirts, but don't want to use anything that will damage the plastic or paint.

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