Quoted from JethroP:
I am looking to replace Q2 in a Gottlieb System 1 power supply. The parts list calls out MJE340K. I am trying to find out what the K suffix means. I have found lots of info on transistor coding, but nothing regarding the suffixes. I have access to an MJE340G but not sure if that is an acceptable replacement. I have also read the TIP85 is an acceptable substitute. But my question is....what does the suffix designate?
Regarding the above answers about the suffix, I agree ... but on the other hand, on an original power supply for Gottlieb SYSTEM-1:
Q2 is not a MJE340 but a TIP31C
and if the package is similar (TO-220/TO-225), the characteristics are very differents.
The TIP31C is a high-power NPN transistor, voltage limit is 100 V and current is about 3 A (peak 5 A).
The MJE340 has a voltage limit to 300 V (OK !) but a current limit to 500 mA , so sure it's not suitable
Sometimes, the suffix indicate a variation in the basic characteristics (speed) but I doubt that a MJE340K will be able to drive 3 A.
TIP85 a subsitute ??? but what is a TIP85 ? This transistor reference doesn't exist
Not only the power is not at all the same, but the pinout of a MJE340 has nothing to do with that of a TIP31C. Base and Emiter pins are crossed :
Check your board : if it's really an original power SYSTEM-1 from Gottlieb, Q2 can't be a MJE340.