[Amps] Resistor Types (Manfred Mornhinweg)

[David Lisney]

In my limited experience of repairing the likes of FT101s I have found 
evidence that the equalising resistors across the HV diodes fail and take 
the rectifiers out with them. These resistors perform two tasks, one as 
"equalisers" and secondly as "bleeders", sadly the failure of the rectifiers 
can end up destroying the mains transformer if not correctly fused. In the 
UK Maplin Electronics stock 1000v rated resistors, I tend to use 1M in place 
of the original 470k and it seems a tidy solution. In the case of the FT101 
it is tidier than to remove the equalisers and put bleeders on the reservoir 
capacitors.

Speaking from bitter experience the FT101 is fine without bleeders or 
equalising resistors, however even when powered off for days the HT is still 
high enough to bite you, jumping backwards in the shack may be my primary 
type of exercise but it is not recommended!

Recently I used some of my "N.O.S" resistors for a project, I was somewhat 
alarmed to find they had gone up in value by approx 20%, may be worth 
checking if you are changing individual resistors across the reservoirs.....

Regards David G0FVT