[Kenwood] TS930s/TS940s PSU regulator transistors 2N5885.

[John E.Cleeve]

Good afternoon Trio/Kenwood users. I have been browsing www.mods.dk. I 
sent the following to the site, and the contents will be of interest 
users of the above equipment. regards, John. G3JVC.


I wish to bring your attention to a serious error in your mods 
listings for the Trio/Kenwood TS930s and TS940s, where, it is said 
that should the 2N5885 power supply regulator transistors fitted to 
both the TS930s and TS940s fail, a replacement is the 2N3771,this 
suggested replacement is WRONG.... for the original 2N5885 is a 60 
volt working transistor, and the suggested replacement, the 2N3771 is 
ONLY a 40 volt working transistor, the 2N3771 will be be working at 
its maximum voltage limit, if fitted in a TS930s, or TS940s, and as 
such, more liable to failure, than the original 2N5885. Power supply 
regulator failure in a TS930s, or TS940s (usually one will go short 
circuit) will cause the 28 volt supply to the PA board to rise to 40 
volts, if over voltage protection has not been fitted to the power 
supply output, serious damage to the PA board transistors will be 
certain, before the PSU internal fuse blows! 
A better, cheaper, direct TO3 replacement for the 2N5885 is the 
MJ15003, (RS Components 296-267) this is a 140 volt working 
transistor, rated at 250 watts, and more than able to cope with the 
power supply demands of the TS930s and TS940s circuitry. 73, John. 
G3JVC.