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Old 7th Dec 2017, 9:40 pm   #48
vishalk
Pentode
 
Join Date: Aug 2017
Location: North London, UK.
Posts: 114
Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

Quote:
Originally Posted by GrimJosef View Post
Much of this happened when Leak discovered that they couldn't exceed the EL84's specifications and get away with it (with previous amplifiers the output valves had generous safety margins, but the EL84 doesn't). So they had to change the output transformer design and also some component values to stop the EL84s going into thermal runaway. The 47k/470k/0.1uF values relate to the later amplifiers which had type 8778 output transformers (you may have labels on the bottom of your transformers giving the type number). The earlier amps had type 3921. If your amp was an early one and it has been to Leak for a service then they will have changed the transformers. So the documentation won't necessarily match the transformers you have.
Thanks Grim that was very helpful, the output transformers are 8778's.
So i will replace with what they were originally fitted with which were 47k/470k/0.1uF values.
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