equivalent for KTD998 and KTB778


2012-05-03 7:17 pm
d998/b778 are in my jensen car amp and one channel is down, searched a little and seen some threads about this and i know the FJA4213 and the FJA4313 are best subtitute

but here's the question, can I replace D998 and B778 with 2SA1943 and 2SC5200?

or with 2SB817/2SD1047?

in replacing what spec is most important. voltages,hfe or...?

is it better to use higher wattage transistors?

wich pair's best?

The 5200 is the same as the 4313 except for the package. If the heatsink and clamping system can accommodate the larger package, you can use them.

Larger packages can dissipate heat more efficiently so they run a bit cooler which can help them to be more reliable. It's possible that you will see no difference in reliability unless the amplifier that they're being used in is improperly designed.
let me give you a small further help, besides the essential by Perry, as of my direct experience KTD998 and KTB788 are self isolated to247 transistors (full "plastic" body) so, if you will replace with FJA- ones (to3p), I suggest you to order as many isolators as transistors to be replaced (at least)... and also if you want your amp to run mono/bridge or tri-mode is better you replace also the good transistors ones to have the full bench same dissipating power....look at Mouser Electronics - Electronic Components Distributor or any other parts supplier you know...