26-09-2011, 06:15 PM
My nephew recently acquired two radios which had been destined for the skip – one was a Ferranti 045 in a sorry state, the other, a Pye 'Fenman1', in better shape cosmetically, and with all the fragile knobs intact, which I believe is not the norm. He asked if I'd restore the Ferranti 045, and said I could keep the Fenman1 for myself. He also gave me about 30 NOS valves which he’d been given, and which I later discovered were worth quite a lot, so I felt obliged to do the best I could for him with the Ferranti. It's a seven valve set (including magic eye & rectifier) covering long, medium and short wave bands on AM, plus VHF FM, with 4 Watts output to a 10" speaker.
I didn’t take a ‘before’ photo and now rather wished I had. The dial had broken into two pieces, and had fallen inside the set. The paint had flaked off the dial back-plate, the veneer was missing from the front edge of the cabinet, the speaker fabric was faded and threadbare, and three brass discs which had lettering on them that indicated volume, waveband, tuning and volume were badly discoloured. My nephew - knowing no better - had plugged in the flimsy two-core single insulated mains flex and said that all the set would do was to make a loud hum ‘which just got louder when he turned up the volume’. Well at least that was a promising sign - where there is life, there is hope, bearing in mind that he hadn't of course plugged in an aerial!
I'll cover the restoration in two parts - this part I'll focus on the electrics, and in part two, the cabinetry.
I was pleased to see that there was a maker’s service sheet that ran to seven pages, but disappointed when I studied it to find that there was no view of either the above chassis or underside - just the circuit to go on. As is my normal practice, I made a cradle to which the inverted chassis was fixed so that I could work on it without trying tp balance the chassis upside down on the bench. I could see from the underside and the circuit diagram that there were several Hunts ‘mouldseal’ caps which would need replacement, some of which had started to disintegrate, so replaced those, and a 50uF 12V electrolytic.
The underside of the chassis can best be described as a rat’s nest. It had two tag-strips, more or less back to back, with some components mounted between the two strips. I managed to identify which component was which from the circuit diagram by tracing the component wires to valveholder tags. With the caps replaced, and a couple of out of spec resistors, I turned my attention to the power supply, tidied up some wiring around the power supply section, and as this is an AC only set, replaced the flimsy two-core flex with a three core one.
The statement by my nephew that the set hummed loudly, suggested that the audio stage worked, but possibly the smoothing caps would need replacement – three in one can - two 24uF and one 16uF. However, nothing was lost by attempting to reform them on my cap reformer, and indeed, after several hours on each section, the leakage dropped to less than half a mA at the rated voltage.
At that stage, having cleaned and lubricated all the ‘switchery’ and pots with Servisol, I connected an aerial, switched the set on via a lamp limiter. Stations were heard on L, M, & S at good volume, but nothing on FM – just a quiet hum, so I checked out the cam mechanism in the permeability tuned FM tuner, which should lift the cores out of the tuning coils, and found that they had seized. I guess that’s the point at which many would reach for a can of WD40, which I dislike with a passion. It isn’t penetrating or dismantling fluid - it’s a water displacement product – hence its name, and unsurprisingly, is rarely successful in freeing seized items such as grub screws on knobs. For that, a product such as ‘Plus Gas’ is the most effective substance. A few drops of that, and the tuning mechanism was working freely within minutes. I smeared the mechanism with Servisol silicon grease.
The set then tuned FM stations in on its backboard mounted foil antenna, but only weakly. Maybe the loss of FM signals was why the set was 'pensioned off' and stored in an attic fro who knows how long? The low volume pointed to a new ECC85 being needed, which are not noted for longevity, so I ordered one which came within 48 hours. The set then performed very well on all bands at excellent volume and audio quality from its ample 10” speaker, with no trace of hum.
Two new 6.3V 0.3 A dial bulbbs were fitted, then the only outstanding electrical item that needed attention was the EM80 tuning indicator, which just glowed very dimly. The voltages were in order, and altered as they should when strong stations were tuned in, so I searched e-bay to see what was on offer. Some EM80s were ridiculously expensive and really, the sellers should be luaghed off the face of the planet, but I found a supplier in Siberia offering sets of four NOS Russian EM80s for just £24.00 inc P&P ‘buy now’. They arrived very securely packed, a month to the date, due to expected delays in the postal service, and worked perfectly.
I've attached a few pics relating to the above, and in part 2, will cover the cabinetry.
I hope the post is of interest, and includes a few useful tips.
I didn’t take a ‘before’ photo and now rather wished I had. The dial had broken into two pieces, and had fallen inside the set. The paint had flaked off the dial back-plate, the veneer was missing from the front edge of the cabinet, the speaker fabric was faded and threadbare, and three brass discs which had lettering on them that indicated volume, waveband, tuning and volume were badly discoloured. My nephew - knowing no better - had plugged in the flimsy two-core single insulated mains flex and said that all the set would do was to make a loud hum ‘which just got louder when he turned up the volume’. Well at least that was a promising sign - where there is life, there is hope, bearing in mind that he hadn't of course plugged in an aerial!
I'll cover the restoration in two parts - this part I'll focus on the electrics, and in part two, the cabinetry.
I was pleased to see that there was a maker’s service sheet that ran to seven pages, but disappointed when I studied it to find that there was no view of either the above chassis or underside - just the circuit to go on. As is my normal practice, I made a cradle to which the inverted chassis was fixed so that I could work on it without trying tp balance the chassis upside down on the bench. I could see from the underside and the circuit diagram that there were several Hunts ‘mouldseal’ caps which would need replacement, some of which had started to disintegrate, so replaced those, and a 50uF 12V electrolytic.
The underside of the chassis can best be described as a rat’s nest. It had two tag-strips, more or less back to back, with some components mounted between the two strips. I managed to identify which component was which from the circuit diagram by tracing the component wires to valveholder tags. With the caps replaced, and a couple of out of spec resistors, I turned my attention to the power supply, tidied up some wiring around the power supply section, and as this is an AC only set, replaced the flimsy two-core flex with a three core one.
The statement by my nephew that the set hummed loudly, suggested that the audio stage worked, but possibly the smoothing caps would need replacement – three in one can - two 24uF and one 16uF. However, nothing was lost by attempting to reform them on my cap reformer, and indeed, after several hours on each section, the leakage dropped to less than half a mA at the rated voltage.
At that stage, having cleaned and lubricated all the ‘switchery’ and pots with Servisol, I connected an aerial, switched the set on via a lamp limiter. Stations were heard on L, M, & S at good volume, but nothing on FM – just a quiet hum, so I checked out the cam mechanism in the permeability tuned FM tuner, which should lift the cores out of the tuning coils, and found that they had seized. I guess that’s the point at which many would reach for a can of WD40, which I dislike with a passion. It isn’t penetrating or dismantling fluid - it’s a water displacement product – hence its name, and unsurprisingly, is rarely successful in freeing seized items such as grub screws on knobs. For that, a product such as ‘Plus Gas’ is the most effective substance. A few drops of that, and the tuning mechanism was working freely within minutes. I smeared the mechanism with Servisol silicon grease.
The set then tuned FM stations in on its backboard mounted foil antenna, but only weakly. Maybe the loss of FM signals was why the set was 'pensioned off' and stored in an attic fro who knows how long? The low volume pointed to a new ECC85 being needed, which are not noted for longevity, so I ordered one which came within 48 hours. The set then performed very well on all bands at excellent volume and audio quality from its ample 10” speaker, with no trace of hum.
Two new 6.3V 0.3 A dial bulbbs were fitted, then the only outstanding electrical item that needed attention was the EM80 tuning indicator, which just glowed very dimly. The voltages were in order, and altered as they should when strong stations were tuned in, so I searched e-bay to see what was on offer. Some EM80s were ridiculously expensive and really, the sellers should be luaghed off the face of the planet, but I found a supplier in Siberia offering sets of four NOS Russian EM80s for just £24.00 inc P&P ‘buy now’. They arrived very securely packed, a month to the date, due to expected delays in the postal service, and worked perfectly.
I've attached a few pics relating to the above, and in part 2, will cover the cabinetry.
I hope the post is of interest, and includes a few useful tips.
Regards, David.
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
