UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

westcliff · 21st Sep 2011, 12:33 am

The new 32uF+32uF can was far too big to fit in the space behind the speaker, so I ordered some single 30uF 450v electrolytics. They arrived at the weekend and I fitted a pair last night.

Tonight I plugged the set into the 100w lamp limiter and ran it with the lamp in circuit. It picked up stations all over MW and a good few on LW but there was a faint buzz right across the dial on both wavebands. The lamp stayed a dull orange throughout.

After 40 minutes, I switched the lamp out, to put full mains through the set. There was an immediate flash and crackle and the set died (I saw all of the valve filaments darkening and the dial lamp went out). The lamp limiter is powered through an RCD; this did not trip off.

Of all the sets I've repaired, six in total, this the first one that has gone bang on me after working on it. Normally when this happens, I replace all of the tubular waxies and as many resistors as necessary, then the radio works. This time, I've already done all of that.

Should my fault-finding begin with the components I haven't replaced?

Gus.

21st Sep 2011, 12:33 am	#15
westcliff Hexode Join Date: Jan 2011 Location: Essex, UK Posts: 396	Re: KB FB10 "Toaster" The new 32uF+32uF can was far too big to fit in the space behind the speaker, so I ordered some single 30uF 450v electrolytics. They arrived at the weekend and I fitted a pair last night. Tonight I plugged the set into the 100w lamp limiter and ran it with the lamp in circuit. It picked up stations all over MW and a good few on LW but there was a faint buzz right across the dial on both wavebands. The lamp stayed a dull orange throughout. After 40 minutes, I switched the lamp out, to put full mains through the set. There was an immediate flash and crackle and the set died (I saw all of the valve filaments darkening and the dial lamp went out). The lamp limiter is powered through an RCD; this did not trip off. Of all the sets I've repaired, six in total, this the first one that has gone bang on me after working on it. Normally when this happens, I replace all of the tubular waxies and as many resistors as necessary, then the radio works. This time, I've already done all of that. Should my fault-finding begin with the components I haven't replaced? Gus.