Re: 475 Time Base Setting Problem


John
 

OK: I think I've found an explanation for the apparent shorting of all timing resistors during fast sweeps.

The relevant switches are S7 and S14, which as shown on my paper Schematic 8*, route the 50V direct to R1089. This renders S9 to S13 inclusive ineffective, which makes no sense.

I've now found an erratum at the back of the manual, showing S8 moved left, i.e inserted into the horizontal trace between S7 and S10. R1082 is always connected to S7.

This circuit drafting correction now makes sense: S9 to S13 switch the timing R's in turn, S15 opens to allow the timing R's to control the fast ramp. So, the presenting problem falls to the S9, R1083/R1084 chain.

John

* signed " mgf 972 " .

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