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Old 13th Sep 2018, 9:12 am   #33
high_vacuum_house
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Join Date: May 2003
Location: Belper Derbyshire
Posts: 1,910
Default Re: Stuck on a BRC 1400!

Good morning,
I am working on a 1400 at the moment. The 23”HMV version. Mine has bottom cramping as well a replacement valve made no difference. Looking to change the 1K pentode grid feed resistor to see if this helps as it has risen in value around 160 ohms.

The heater chain has a connection to the frame oscillator so that if the diode sent S/C the frame would not lock. Might be worth connecting an ammeter in the heater circuit best place would be on the tube base then at the top of the chain to see if any of the decoupling capacitors are leaking.

Christopher Capener
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Interests in the collection and restoration of Tefifon players and 405 line television
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