TES Tecnica AF1077 FM/AM generator - UK Vintage Radio Repair and Restoration Discussion Forum

Ted Kendall · 12th Jan 2021, 8:45 pm

It's like this - I saw this on an auction site, parts or not working, and fancied a go. Never heard of this make before - made in Milan.

I shudder to think of what the poor thing has been through - stored in very damp conditions for some time, and has been subject to the attentions of the phantom bodger. Anyway. gird the loins and off we go!

First thing, intermittent and poor output at RF. Generator box opened up. 26 screws - count 'em. 25 were as original, the other was some brass hinge thing - somebody's been here before. The mode switch (AM, FM1, FM2) had a bent contact on one wafer. There was little to do but use a spare way on the other wafer of the switch, keeping layout/length changes to the minimum - this is RF, after all - and this at least gave an output. The AM range switch was looking pretty sorry for itself, so dosed with Servsol. On test, some output on all ranges, but calibration way out and varying across the dial. Left it on overnight and that bit started to behave - dried out, like as not.

Next - AM and FM modulation are on separate knobs, with pull switches for external mod. Fine - except the AM one wouldn't pull. Stuck fast. Ever pulled apart a pull-switched Ruwido pot? I have. The sticking was caused by corrosion on the shaft jamming in its plastic hub. Servisol, Q-tip, heave and shove, Q-tip, Servisol...you get the idea. About an hour and a half of this, plus a smidge of Starrett oil on the shaft and it all went back together sweet as a nut.

No deviation on FM at all, never mind stereo. One wire to the pot board fallen off - reattached - mono deviation, but no stereo. Inspection of the encoder board. It was here that the phantom really got goimg. Untidy but functional replacement of the chip regs, ghastly use of underpowered soldering iron, scraping away at the board, lifted and bridged tracks, but corrosion around IC pins ignored. Pin 1 fell off a 4049 as I was checking the volts on it. Replaced. Still no stereo. Traced it through the circuit as far as the last chip which combines multiplex and pilot tone. Output on the rail. Closer inspection showed Pin 4 folded under and not making contact. 4558s don't like missing rails. Replaced with 072 which was to hand.

With all this done, at last some multiplex output! But now I'm up against the twiddlings of the phantom. Levels and internal meter readings don't agree, I don't know what's been twiddled which way and don't have adjustment instructions, only the circuit diagrams. Does anybody have any information?

12th Jan 2021, 8:45 pm	#1
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,675	TES Tecnica AF1077 FM/AM generator It's like this - I saw this on an auction site, parts or not working, and fancied a go. Never heard of this make before - made in Milan. I shudder to think of what the poor thing has been through - stored in very damp conditions for some time, and has been subject to the attentions of the phantom bodger. Anyway. gird the loins and off we go! First thing, intermittent and poor output at RF. Generator box opened up. 26 screws - count 'em. 25 were as original, the other was some brass hinge thing - somebody's been here before. The mode switch (AM, FM1, FM2) had a bent contact on one wafer. There was little to do but use a spare way on the other wafer of the switch, keeping layout/length changes to the minimum - this is RF, after all - and this at least gave an output. The AM range switch was looking pretty sorry for itself, so dosed with Servsol. On test, some output on all ranges, but calibration way out and varying across the dial. Left it on overnight and that bit started to behave - dried out, like as not. Next - AM and FM modulation are on separate knobs, with pull switches for external mod. Fine - except the AM one wouldn't pull. Stuck fast. Ever pulled apart a pull-switched Ruwido pot? I have. The sticking was caused by corrosion on the shaft jamming in its plastic hub. Servisol, Q-tip, heave and shove, Q-tip, Servisol...you get the idea. About an hour and a half of this, plus a smidge of Starrett oil on the shaft and it all went back together sweet as a nut. No deviation on FM at all, never mind stereo. One wire to the pot board fallen off - reattached - mono deviation, but no stereo. Inspection of the encoder board. It was here that the phantom really got goimg. Untidy but functional replacement of the chip regs, ghastly use of underpowered soldering iron, scraping away at the board, lifted and bridged tracks, but corrosion around IC pins ignored. Pin 1 fell off a 4049 as I was checking the volts on it. Replaced. Still no stereo. Traced it through the circuit as far as the last chip which combines multiplex and pilot tone. Output on the rail. Closer inspection showed Pin 4 folded under and not making contact. 4558s don't like missing rails. Replaced with 072 which was to hand. With all this done, at last some multiplex output! But now I'm up against the twiddlings of the phantom. Levels and internal meter readings don't agree, I don't know what's been twiddled which way and don't have adjustment instructions, only the circuit diagrams. Does anybody have any information?