The simasimac page at
http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html
has a nice chart of various flyback numbers and which have the bleeder. It appears that 157-0042 had the bleeder in all ABC versions. The numbers appear to be from Larry Pina Macintosh Repair and Upgrade Secrets 1990 page 95, with the addition of bleeder info from Appendix C/D and elsewhere. It looks like the B version was the recommended replacement in 1990. I know that the A version had a tendency to have herringbone pattern failures (Pina, Dead Mac Scrolls 1992 page 145) and he recommended the C version for replacements. Don't know what issues were addressed going from B to C. But I notice I have an A version on my spare reference analog board that was working just fine a few years ago, I would gladly use it as a donor to rescue one of my existing SE/30s if need arises. I'm sure C is better somehow, but a working A or B is a lot better than a paperweight. Elsewhere on the Internet I read today that the low cost of monitors has led to the collapse of the repair infrastructure and parts distributors for all but the most expensive monitors in the US. Cheaper to get a new one. This may explain the single digit prices for flybacks (presumably for smaller CRTs) from certain distributors while others hold out for $35 (presumably for giant CRTs).
http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html
has a nice chart of various flyback numbers and which have the bleeder. It appears that 157-0042 had the bleeder in all ABC versions. The numbers appear to be from Larry Pina Macintosh Repair and Upgrade Secrets 1990 page 95, with the addition of bleeder info from Appendix C/D and elsewhere. It looks like the B version was the recommended replacement in 1990. I know that the A version had a tendency to have herringbone pattern failures (Pina, Dead Mac Scrolls 1992 page 145) and he recommended the C version for replacements. Don't know what issues were addressed going from B to C. But I notice I have an A version on my spare reference analog board that was working just fine a few years ago, I would gladly use it as a donor to rescue one of my existing SE/30s if need arises. I'm sure C is better somehow, but a working A or B is a lot better than a paperweight. Elsewhere on the Internet I read today that the low cost of monitors has led to the collapse of the repair infrastructure and parts distributors for all but the most expensive monitors in the US. Cheaper to get a new one. This may explain the single digit prices for flybacks (presumably for smaller CRTs) from certain distributors while others hold out for $35 (presumably for giant CRTs).