Moderator- if this is in the wrong forum please move. Not having much background in solid state servicing finds me in this situation: I'm restoring a 1965 Sony videocorder. In searching for replacement transistors I’m not familiar with the meaning of the digit after the dash in the part numbers. Is this last number significant from a rating standpoint or can it be ignored? These transistors are used in the servo control circuit. What follows are the Sony transistor part numbers in question.

2SC401-4
2SC401-6
2SC318-16
2SC299-4

An example is the 2SC401-6. Using 2SC401 without the 6 indicates 2N3710 as a sub using an online cross reference guide. Subs were found for the others by using the part numbers without the last digit(s).

A 2SC4016 transistor exists. Could this be the same as 2SC401-6 with the dash omitted as in an updated numbering system?

Thank you very much, Rick

The numbers after the dashes are probably just production codes of some sort. I really can only guess at what the numbers actually mean, but I'm at least pretty certain that they don't mean anything that matters much for purposes of finding a modern substitute. The 2SC4016 is a quite different transistor from the 2SC401, as is the 2SC4014.

I believe the 2N3710 is quite long obsolete, and there's nothing particularly special about it anyway, so I'd look for something else for the 2SC401. You'll probably want a second opinion before you buy anything, since I'm nowhere near an expert at this sort of thing, but I think a 2SC945 would work fine. Depending on how much power is actually going through the 2SC318, you may be able to use a 2SC945 for that one as well... the 2SC945 is rated at 50mw less, but it looks pretty good otherwise.