151-0367-00 and 151-0402-00 transistors
These are likely to be leaky from C to E as a diode while checking normal
as an NPN. An hfe meter will show way off hfe on the leaky ones. If they
have round leads (tarnished above the socket), they are all leaky. If the
flat face is black with square leads, they likely will be leaky. Check
EVERY one. Some will be leaky and some not even in the same piece. If the
flat face is blue with square leads, it will be fine. The blue flat ones
must be a manufacturing change or different supplier. The 151-0402-00 is in
the 7D15. It may be in other plug-ins. The same checking applies to the
0402. I found that KSP10BU will replace them. Mouser carries these
transistors. The pinout is BEC so be careful when inserting them. The flat
will be turned different than original ones. I had some plug-ins and scopes
that were not quite right in operation after restoring them. These
transistors were the problem. In the Q list of parts, they will have "SEL
FROM 3571TP" under "name and description".
I have an alternate part number for 151-0367-00. The TI part number is SKA6516. The Freescale number is SPS8811. I have a bunch of the Tek number 151-0367-00. They have all been pulled from one of the old production lines; formed and cut leads, some bent. They appear to have been through some hand selection process for matching. If someone needs a few to try, let me know and I'll send a few.
If you search through the Tektronix Common Design Parts catalog dated October 1982
you will find that these two parts have many part number gyrations. The -0367 is crossed over to a AST3571 which appears to be a custom 2N3571. Later in the catalog the part number SKA6516 appears. Also later on in the catalog you will see the
-0367 being selected and placed under a different Tek part numbers probably for use in other instruments.
The -0402 is used in the 7D15 and SG503 plus other units. The catalog crosses it over to a standard 2N3571 but later crosses it over to the AST3571 and then a SKA6814.
Confusing indeed. I’m assuming that the part number migration was probably due to ongoing revisions to the catalog.