Re: 475 instead of 475A?

Ashton Brown <ashton@...>

Hello Steve,

Couple comments - BTW I have had a 475A SN B025698 for several years. Rock solid except.. for a need to retighten the BNC input mount nuts and look for bad connections at AC--GND--DC input switch. Doesn't get a lot of use, but so far turns on and just runs.

Since you mention audio - have you considered a clean 454A? larger screen than 453,4; 2mV/DIV - a usually conservative 150 MHz, as I've measured to near 200 on a couple. It has the fine trace-width which the 46x, 47x CRTs cannot equal and overall (and IMhO) built to better standards than that later series. In any of these cases - you're likely to need to pay attention to the filter caps, using an ESR meter - like the small IC-based box made by an Australian company (kit form even). I built it; it works -- and you can't really test w/out it, only guess or R&R blindly.

I admit a prejudice for the 454A especially - you really Can see the tiny wiggles on that ultra-sharp trace.. and they are not artifacts of the scope - particularly useful to filter-designers I am told - estimating the remaining octave-band noise for various designs with wonderful Russian names.


tss_steve_990 wrote:

Thank you all who helped with the serial number mystery.
Since I last posted I came to the realization that the 475 had 2mv/div sensitivity instead of the 5mv/div of the 475A. Since my primary work is with professional audio equipment where we are looking at low level signals (power supply noise, and subtle oscillations, for example) I've come to the conclusion that I should be looking for a used, late model, pristine condition 475 instead of the 475A. I have found our that on 475's that SN of B-250000 and upwards are 1977 vintage or newer according to the front page of a 1977 Revision 475 service manual CD being offered on ebay.

I've already searched for posts on 475 updates, so I know what to look for re: the rectier, power resistor and PSU capacitor. Are there any warnings that you guys can offer re: my direction to pursue a 475 instead of the 475A?

Thanks for your input!


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