Fergusonic Mains Minor - First of the Rountuits - UK Vintage Radio Repair and Restoration Discussion Forum

yestertech · 28th May 2012, 10:59 pm

Further to my "Rountuit" repairs offer , I am delighted to announce that the first candidate off the bench is this rather nice Fergusonic Mains Minor.

Its a diminutive 5 valve full superhet , complete with mains transformer. MW and SW only on this one. It must be about the only set I've repaired to use an EL32 - I've heard about sets with them in ( sometimes in P-P ) but never in the flesh. Having seen this radio many times on the trader sheet, I had imagined a much larger set - The ruler says it all !
Viewed from the back, it's easy to think that there is no valve rectification, but as you can see, the AZ31 is in fact shoe-horned into the corner of the chassis adjacent to the speaker.

As you can see, it had been rather neglected over the years but nothing too major. Having parted chassis and cabinet, I pulled the AZ31 and did the AC tests. On came the dial bulb and HT was present on the anode pins so encouraging start. I then attached my DC PSU with limiter lamp to the un-powered chassis HT line, to ascertain the condition of the electrolytics on the HT line.

Nothing - Nada - Absolutely no current flow at all. But not a fault, just 2 completely dried out and useless original caps, dated 1946 and both contained in the large brown can visible in the picture. Further measurements proved HT was "circulating" around the chassis, so the mains was reconnected and HT current flowed after a short time. It was quickly proved "that cap" was seriously leaky, so it was replaced and that reduced the HT current quite a bit. After a quick clean of the wavechange switch with DEOXIT, some very faint signals could be heard on both bands. A sigh of relief as at this point it was safe to assume a full repair would be possible.

First job was to rebuild the area containing the dual electrolytic. To one of its tags was soldered the earthy end of a cathode bypass cap. This in turn was adjacent to another bypass cap. These are used for a) the OP valve and b) the 3 remaining valves respectively. ( a nice piece of cost cutting ! ). I would normally put new parts in and be done with it, but just this once I thought I'd try and re-stuff them. This turned out to be easier than I thought, at least for the second cap :
Remove label sleeve
slit cardboard tube along the back
remove end caps and old foil etc
Drill end caps to take new leadouts ( I couldn't get anything to adhere to the end caps )
Attach new electrolytics to suitable size SWG poked through the end caps.
Reassemble, and twist old wire stubs around new for rigidity and solder
Add suitable "period" sleeving.

Once the new HT electrolytic was in place ( suitably hidden in a brown cover to avoid the usual bright blue dazzle !) the cathode bypass caps were reinstalled. It's a good job the AZ31 uses few of its 8 pins, as much use has been made of the valveholder tags to facilitate other connections such as one to the cathode of the EL32 which provides the anchor for its now restuffed bypass cap. Now the set was back on its own PSU, the business of sorting out the faint signals could begin in earnest

The set seemed rather deaf when fed with stated 470 KHz IF. An early test to see whether IF alignment was needed resulted in a loud howl when the trimmers in the IFTs were turned slightly in one direction. So this time, the measurement was a bit more scientific. In fact, the trimmers were more than a little out but as the gain increased the howling began again. One only had to see that the IF amp was EF39 and you can guess the rest. With a new valve installed, the IFTs were peaked properly and the gain increased a good 15 dB or more.
Stations were now coming in much louder , but as I tuned below about 300m, the set seemed to get very quiet. The first step in the alignment is the dial pointer and this was not in the correct position, as defined in the trader sheet. A simple loosen and re-tighten of the screw was all that it needed, but it was slightly fouling the cardboard dial, so a couple of small washers were used behind the pointer.
Despite a couple of goes "around" the alignment sequence I could not get the gain even at opposite ends of the dial. At this point I ignored the set for a few days to concentrate on other matters. A post for advice yielded some promising ideas, but nothing which seemed to lead to a 'culprit'
Having checked all the trimmer values with my LCR tester and confirmed they were working OK, I remeasured all the caps and resistors , and even tried a new ECH35 to no avail.
Finally, I wound out all the trimmers and started again on the alignment sequence .For some reason, this time it seemed to improve. After shuttling up and down the band a few times, I had the sensitivity reasonably even between 200m and 500m. Connecting my rather poor aerial brought reasonable signals at the extreme HF end of MW , given that where my workshop is, at ground level and banked by the garden, reception is usually somewhat mediocre. The alignment on SW was then checked and needed very little adjustment.

And so to the cabinet. This was quite dry and in need of much nourishment but otherwise not too bad for a 60 + year old set. I applied 2 good rubs of finish reviver, made from a recipe I found online, followed by some danish oil. When this had soaked in a couple of coats of light brown wax polish followed. Whilst the finish will never be pristine, the more even tone has obscured many marks especially those made on the cabinet adjacent to the wavechange switch. The curved edge atop the speaker baffle was covered in years of fluff and dirt, so the baffle was removed and given a gentle wipe with a damp cloth, to which some stain remover was added. Any more then gentle cleaning could have resulted in torn or shrinking material. I always maintain a slightly grubby cloth is probably better than a gap or a hole !!! Sadly one of the 3 knobs is broken, and I was convinced I had one somehwere in the same pattern,albeit brown. Whilst I was prepared to repaint it, said knob has not yet come to light......

I rather like this set, but as the criterion for this exercise was not having to find space of new sets, I can at least now hand it back to its owner and not risk the wrath of SWMBO !!!

Andy

yestertech · 28th May 2012, 11:05 pm

And a few after pics. One slight setback occured during soak testing - the set "died" completely. This was traced to an intermittent connection at the voltage selector panel on top of the mains transformer.
This was hard wired ( see pic ) to prevent any further problems.

AND SO TO KB TOASTER !!

A.

ppppenguin · 29th May 2012, 9:31 am

What a lovely job! Thankyou. AFAIK this set was owned from new by my grandma. I inherited it, played with it for a few years, replaced the mains lead when it exploded, and bunged it in the loft. It's sat untouched for about 40 years and a couple of house moves and was perenially at the bottom of the round tuit pile.

I look forward to seeing it again at Harpenden and making a suitable contribution to Museum funds.

howard · 31st May 2012, 4:15 pm

Good work Andy

I really like that little radio, I shall look out for one, I think I've just about got enough room for it ......

Howard

28th May 2012, 10:59 pm	#1
yestertech Nonode Join Date: Dec 2002 Location: Coulsdon, Surrey, UK. Posts: 2,132	Fergusonic Mains Minor - First of the Rountuits Further to my "Rountuit" repairs offer , I am delighted to announce that the first candidate off the bench is this rather nice Fergusonic Mains Minor. Its a diminutive 5 valve full superhet , complete with mains transformer. MW and SW only on this one. It must be about the only set I've repaired to use an EL32 - I've heard about sets with them in ( sometimes in P-P ) but never in the flesh. Having seen this radio many times on the trader sheet, I had imagined a much larger set - The ruler says it all ! Viewed from the back, it's easy to think that there is no valve rectification, but as you can see, the AZ31 is in fact shoe-horned into the corner of the chassis adjacent to the speaker. As you can see, it had been rather neglected over the years but nothing too major. Having parted chassis and cabinet, I pulled the AZ31 and did the AC tests. On came the dial bulb and HT was present on the anode pins so encouraging start. I then attached my DC PSU with limiter lamp to the un-powered chassis HT line, to ascertain the condition of the electrolytics on the HT line. Nothing - Nada - Absolutely no current flow at all. But not a fault, just 2 completely dried out and useless original caps, dated 1946 and both contained in the large brown can visible in the picture. Further measurements proved HT was "circulating" around the chassis, so the mains was reconnected and HT current flowed after a short time. It was quickly proved "that cap" was seriously leaky, so it was replaced and that reduced the HT current quite a bit. After a quick clean of the wavechange switch with DEOXIT, some very faint signals could be heard on both bands. A sigh of relief as at this point it was safe to assume a full repair would be possible. First job was to rebuild the area containing the dual electrolytic. To one of its tags was soldered the earthy end of a cathode bypass cap. This in turn was adjacent to another bypass cap. These are used for a) the OP valve and b) the 3 remaining valves respectively. ( a nice piece of cost cutting ! ). I would normally put new parts in and be done with it, but just this once I thought I'd try and re-stuff them. This turned out to be easier than I thought, at least for the second cap : Remove label sleeve slit cardboard tube along the back remove end caps and old foil etc Drill end caps to take new leadouts ( I couldn't get anything to adhere to the end caps ) Attach new electrolytics to suitable size SWG poked through the end caps. Reassemble, and twist old wire stubs around new for rigidity and solder Add suitable "period" sleeving. Once the new HT electrolytic was in place ( suitably hidden in a brown cover to avoid the usual bright blue dazzle !) the cathode bypass caps were reinstalled. It's a good job the AZ31 uses few of its 8 pins, as much use has been made of the valveholder tags to facilitate other connections such as one to the cathode of the EL32 which provides the anchor for its now restuffed bypass cap. Now the set was back on its own PSU, the business of sorting out the faint signals could begin in earnest The set seemed rather deaf when fed with stated 470 KHz IF. An early test to see whether IF alignment was needed resulted in a loud howl when the trimmers in the IFTs were turned slightly in one direction. So this time, the measurement was a bit more scientific. In fact, the trimmers were more than a little out but as the gain increased the howling began again. One only had to see that the IF amp was EF39 and you can guess the rest. With a new valve installed, the IFTs were peaked properly and the gain increased a good 15 dB or more. Stations were now coming in much louder , but as I tuned below about 300m, the set seemed to get very quiet. The first step in the alignment is the dial pointer and this was not in the correct position, as defined in the trader sheet. A simple loosen and re-tighten of the screw was all that it needed, but it was slightly fouling the cardboard dial, so a couple of small washers were used behind the pointer. Despite a couple of goes "around" the alignment sequence I could not get the gain even at opposite ends of the dial. At this point I ignored the set for a few days to concentrate on other matters. A post for advice yielded some promising ideas, but nothing which seemed to lead to a 'culprit' Having checked all the trimmer values with my LCR tester and confirmed they were working OK, I remeasured all the caps and resistors , and even tried a new ECH35 to no avail. Finally, I wound out all the trimmers and started again on the alignment sequence .For some reason, this time it seemed to improve. After shuttling up and down the band a few times, I had the sensitivity reasonably even between 200m and 500m. Connecting my rather poor aerial brought reasonable signals at the extreme HF end of MW , given that where my workshop is, at ground level and banked by the garden, reception is usually somewhat mediocre. The alignment on SW was then checked and needed very little adjustment. And so to the cabinet. This was quite dry and in need of much nourishment but otherwise not too bad for a 60 + year old set. I applied 2 good rubs of finish reviver, made from a recipe I found online, followed by some danish oil. When this had soaked in a couple of coats of light brown wax polish followed. Whilst the finish will never be pristine, the more even tone has obscured many marks especially those made on the cabinet adjacent to the wavechange switch. The curved edge atop the speaker baffle was covered in years of fluff and dirt, so the baffle was removed and given a gentle wipe with a damp cloth, to which some stain remover was added. Any more then gentle cleaning could have resulted in torn or shrinking material. I always maintain a slightly grubby cloth is probably better than a gap or a hole !!! Sadly one of the 3 knobs is broken, and I was convinced I had one somehwere in the same pattern,albeit brown. Whilst I was prepared to repaint it, said knob has not yet come to light...... I rather like this set, but as the criterion for this exercise was not having to find space of new sets, I can at least now hand it back to its owner and not risk the wrath of SWMBO !!! Andy Attached Thumbnails Last edited by yestertech; 28th May 2012 at 11:02 pm. Reason: added pics

28th May 2012, 11:05 pm	#2
yestertech Nonode Join Date: Dec 2002 Location: Coulsdon, Surrey, UK. Posts: 2,132	Re: Fergusonic Mains Minor - First of the Rountuits And a few after pics. One slight setback occured during soak testing - the set "died" completely. This was traced to an intermittent connection at the voltage selector panel on top of the mains transformer. This was hard wired ( see pic ) to prevent any further problems. AND SO TO KB TOASTER !! A. Attached Thumbnails Last edited by yestertech; 28th May 2012 at 11:13 pm.

29th May 2012, 9:31 am	#3
ppppenguin Retired Dormant Member Join Date: Dec 2003 Location: North London, UK. Posts: 6,168	Re: Fergusonic Mains Minor - First of the Rountuits What a lovely job! Thankyou. AFAIK this set was owned from new by my grandma. I inherited it, played with it for a few years, replaced the mains lead when it exploded, and bunged it in the loft. It's sat untouched for about 40 years and a couple of house moves and was perenially at the bottom of the round tuit pile. I look forward to seeing it again at Harpenden and making a suitable contribution to Museum funds.

31st May 2012, 4:15 pm	#4
howard Nonode Join Date: May 2005 Location: Godalming, Surrey, UK. Posts: 2,593	Re: Fergusonic Mains Minor - First of the Rountuits Good work Andy I really like that little radio, I shall look out for one, I think I've just about got enough room for it ...... Howard Last edited by howard; 31st May 2012 at 4:26 pm.