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Old 13th Nov 2011, 2:16 pm   #53
westcliff's Avatar
Join Date: Jan 2011
Location: Essex, UK
Posts: 356
Default Re: KB FB10 "Toaster"

I was up past 3 o'clock this morning testing the set. I'd check various connections (the smoothing capacitor connections were all good), and switch on, with good results. Then I'd slide the case on and test again and it would be fine. When I screwed the case on and switched on, the noise would return. Quite frustrating it was.

After ensuring the case screws weren't touching any components or wiring, I came to the conclusion that the final few millimetres where the case and the base were being tightened together was pushing something against something else, with unwanted consequences.

There is very little vertical clearance underneath the chassis and I did find two components protruding. One was the capacitor between V4 and V3 and the other was a resistor between V4 and the chassis. The capacitor could have its wire pushed into contact with an unused pin on the V4 socket and the resistor could press against a number of chassis connections and had in fact separated two of them so that their contact was at best intermittent. These components have now been moved to where the can do no harm. This evening I will re-attach the case and hopefully the set will work.

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