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Old 15th Jul 2017, 7:10 pm   #15
crackle
Rest in Peace
 
Join Date: Mar 2011
Location: Basildon, Essex, UK.
Posts: 4,100
Default Re: Restore of KB 428

I have been continuing to change/restuff capacitors. Many of the capacitors are contained in metal cans holding 2 or 3 capacitors. They are fairly easy to get into and dig the old contents out.
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There have been about 5 resistors which have needed changing, a couple were open circuit with no visible signs of damage, one was actually blackened where a very leaky capacitor had caused excess current, and 2 were way off spec.
Where possible I have tried to do a sympathetic electrical restore, and have used other vintage dog bone type resistors where I could find ones of correct value. Where the value no longer matched the markings I have repainted a couple.
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The wiring which went to the neon tuning indicator and the dial lamps was rubber and was flaking away so that has been replaced. There is some more but it is buried under a lot of other stuff and is going to be more difficult to extract.
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Anyway nearly there, with the main chassis anyway, just a few more jobs to do. Then I am going to take the power supply shelf out of a KB 540 so I can test this chassis.

It will then be a matter of making a new power supply shelf for this radio from scratch.

Mike

p.s.
For some strange reason KB omitted R24 V5 grid stopper on the under chassis layout, I have drawn it in on this clip from the layout drawing, and updated the service manual on my website.
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Last edited by crackle; 15th Jul 2017 at 7:34 pm.
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