20-04-2012, 06:46 PM
Hi
Pilot Little Maestro Restoration.
This was the last of four sets kindly given to me by my friend Henry Cavnagh before he sadly died in April 2007. The set was put away to await its repair for a future date which arrived in September.
At first glance, this 1939 Little Maestro in walnut cabinet looked in good general condition, all the original knobs were present and it had the correct back panel. The resistive line cord was missing. A closer inspection to its cabinet revealed open joints, peeling veneer and patches of missing finish.
The three chassis mounting screws were missing so with the knobs removed the chassis came out easily. On top of the chassis, supplied loose was a brand new volume control with mains switch together with a large old resistor? All the valves tested at 100% emission as Henry said they would. Turning the chassis over someone had been busy with snips, it looked a mess. Two days were spent trying to sort out the chassis. Paul Stenning’s excellent capacitor dropper spreadsheets were downloaded and a 4.2uF dropper was made up to replace the resistive line cord. The chassis had missing components and additional components had been installed not shown on the service sheets. By now I was going round in circles and getting nowhere, the chassis still looked a mess and the cabinet wasn’t much better so I decided to do a full restoration.
Chassis fully stripped revealing a lot of solder.
The chassis was totally stripped marking each component. Large amounts of solder had been used to directly connect components to chassis; even the two stacks of tuning coils at the front end were soldered to chassis. A hole was drilled in each location as the solder was removed, solder tags would be added later. The chassis was then rubbed down to bright metal and painted. The valve holders were then fitted and with the valves installed a proper job could be made of the new dropper. Using a Variac and an assortment of class X2 capacitors it was found that 5uF gave 67V across the heater chain which was just 1V down on spec. a neat job was made of the dropper by encasing it together with its discharge resistor in heat shrink sleeving with a single length of mains cable for connection. The rest of the components were added to the chassis surprisingly quickly.
Chassis ready for paint and painted.
With power switched on the valves obviously lit up but nothing else, HT on the valve pins was very high but the loudspeaker was silent. This was expected as I’m still a novice on chassis work. Now was the time to learn how to use a signal generator having bought two previously but never using them? An e-mail was sent to my friend and fellow BVWS member Martin Scobie asking for instructions to which Martin promptly replied. What a difference the signal generator made? With a bit of work it didn’t take long working backwards from the loudspeaker before a signal could be passed from V1 to the loudspeaker, at this point only one station could be heard very weakly? This set doesn’t have an aerial socket which threw me for quite a while until I realized that one of the original bits of wire under the chassis must have been the aerial? With the workshop aerial hooked up the set burst into life, the amount of volume was most impressive for such a small set. The new dropper tucked in snugly against the loudspeaker. The new volume control and old resisitor not needed? Martin’s instructions saved a great deal of time and frustration and with his help I’ve come to realize what a very useful instrument a signal generator is.
Testing capacitor dropper; Fully restored chassis and snug fitting dropper..
With a fully working chassis the cabinet restoration was next. The original finish was removed with paint stripper due to the damaged veneer otherwise a cabinet scraper would have been used. The front top right hand corner was worst as part of the walnut facing veneer had become detached and had a very small piece missing. In the same area a section of the front had become detached and there were many splits to the face veneer. Both top back corner joints had opened up.
This work was broken down into sections with the detached front being tackled first. Gummed tape was applied around the repair area to protect the stripped surfaces from the hot hide glue. Matchsticks were used to hold the sections open so that hot hide glue could be worked in, the matchsticks were then removed and the sections quickly brought together removing the excess glue with a damp cloth, more gummed tape was applied to hold everything firmly together until the glue set. The detached corner veneer was then re-glued with hot hide glue and again taped tightly in position removing excess glue with the cloth. Once the glue had set a small piece of walnut veneer was selected and cut to replace the missing piece taking care to get a good match. This was then glued and taped into place. Hot hide glue was then brushed into the many splits wiping away the excess and allowing it to dry.
Finally both back corners were repaired in similar manner but this time held tightly closed with a home made sash cramp until the glue had set. All was going well until the wooden grille was being rubbed down with wire wool; the grille suddenly broke into two parts adding yet another repair to the list. The grille was easily repaired with hide glue. With all the repairs completed the cabinet was gently rubbed down with 400 grit abrasive paper and dusted off. The next job was pure magic, the cabinet was given a coat of raw linseed oil, and the effect of applying oil has to be seen to be believed as the colour of the veneers jump out at you. Excess oil was removed with a cloth and the cabinet was left alone for a full day to let the oil dry. Stain was not used. Four coats of button shellac were then applied using an artist’s fan brush letting each coat dry for 30 minutes before applying the next coat. The grille was also given four coats of shellac; the shellac was then left to dry overnight.
Fragile grille and ready for hide glue.
The following day the cabinet was well flatted with 400 grit wet or dry abrasive paper used dry then French polishing proper could begin using a traditional polishing rubber made up of a soft cotton outer layer and skin wadding inner. Due to the small size of this set the polishing rubber could only be used for short periods at a time before the surface became unworkable and had to be left alone to dry. I never use oil to lubricate the rubber preferring to use patience and a bit more time to achieve good results. After two days of using the rubber the cabinet was well worked up with shellac and put to one side for a week in a warm place to let the shellac harden.
With the shellac hardened burnishing cream was used to produce a glass like finish. Given the fragile state of the grille, no further work was attempted to improve on the four brush coats of shellac, one break was one too many. The final job was to fully assemble the set and stand back to admire it. It’s a pretty little set and my wife Bronwyn soon claimed it, finding a home for it in our front room.
Bronwyn found it a home.
I still have a number of abused sets under the bungalow to restore and hope people keep snipping leads as I’m getting a nice collection together. I think Henry would have been pleased with the result.
Kind regards, Col.
Pilot Little Maestro Restoration.
This was the last of four sets kindly given to me by my friend Henry Cavnagh before he sadly died in April 2007. The set was put away to await its repair for a future date which arrived in September.
At first glance, this 1939 Little Maestro in walnut cabinet looked in good general condition, all the original knobs were present and it had the correct back panel. The resistive line cord was missing. A closer inspection to its cabinet revealed open joints, peeling veneer and patches of missing finish.
The three chassis mounting screws were missing so with the knobs removed the chassis came out easily. On top of the chassis, supplied loose was a brand new volume control with mains switch together with a large old resistor? All the valves tested at 100% emission as Henry said they would. Turning the chassis over someone had been busy with snips, it looked a mess. Two days were spent trying to sort out the chassis. Paul Stenning’s excellent capacitor dropper spreadsheets were downloaded and a 4.2uF dropper was made up to replace the resistive line cord. The chassis had missing components and additional components had been installed not shown on the service sheets. By now I was going round in circles and getting nowhere, the chassis still looked a mess and the cabinet wasn’t much better so I decided to do a full restoration.
Chassis fully stripped revealing a lot of solder.
The chassis was totally stripped marking each component. Large amounts of solder had been used to directly connect components to chassis; even the two stacks of tuning coils at the front end were soldered to chassis. A hole was drilled in each location as the solder was removed, solder tags would be added later. The chassis was then rubbed down to bright metal and painted. The valve holders were then fitted and with the valves installed a proper job could be made of the new dropper. Using a Variac and an assortment of class X2 capacitors it was found that 5uF gave 67V across the heater chain which was just 1V down on spec. a neat job was made of the dropper by encasing it together with its discharge resistor in heat shrink sleeving with a single length of mains cable for connection. The rest of the components were added to the chassis surprisingly quickly.
Chassis ready for paint and painted.
With power switched on the valves obviously lit up but nothing else, HT on the valve pins was very high but the loudspeaker was silent. This was expected as I’m still a novice on chassis work. Now was the time to learn how to use a signal generator having bought two previously but never using them? An e-mail was sent to my friend and fellow BVWS member Martin Scobie asking for instructions to which Martin promptly replied. What a difference the signal generator made? With a bit of work it didn’t take long working backwards from the loudspeaker before a signal could be passed from V1 to the loudspeaker, at this point only one station could be heard very weakly? This set doesn’t have an aerial socket which threw me for quite a while until I realized that one of the original bits of wire under the chassis must have been the aerial? With the workshop aerial hooked up the set burst into life, the amount of volume was most impressive for such a small set. The new dropper tucked in snugly against the loudspeaker. The new volume control and old resisitor not needed? Martin’s instructions saved a great deal of time and frustration and with his help I’ve come to realize what a very useful instrument a signal generator is.
Testing capacitor dropper; Fully restored chassis and snug fitting dropper..
With a fully working chassis the cabinet restoration was next. The original finish was removed with paint stripper due to the damaged veneer otherwise a cabinet scraper would have been used. The front top right hand corner was worst as part of the walnut facing veneer had become detached and had a very small piece missing. In the same area a section of the front had become detached and there were many splits to the face veneer. Both top back corner joints had opened up.
This work was broken down into sections with the detached front being tackled first. Gummed tape was applied around the repair area to protect the stripped surfaces from the hot hide glue. Matchsticks were used to hold the sections open so that hot hide glue could be worked in, the matchsticks were then removed and the sections quickly brought together removing the excess glue with a damp cloth, more gummed tape was applied to hold everything firmly together until the glue set. The detached corner veneer was then re-glued with hot hide glue and again taped tightly in position removing excess glue with the cloth. Once the glue had set a small piece of walnut veneer was selected and cut to replace the missing piece taking care to get a good match. This was then glued and taped into place. Hot hide glue was then brushed into the many splits wiping away the excess and allowing it to dry.
Finally both back corners were repaired in similar manner but this time held tightly closed with a home made sash cramp until the glue had set. All was going well until the wooden grille was being rubbed down with wire wool; the grille suddenly broke into two parts adding yet another repair to the list. The grille was easily repaired with hide glue. With all the repairs completed the cabinet was gently rubbed down with 400 grit abrasive paper and dusted off. The next job was pure magic, the cabinet was given a coat of raw linseed oil, and the effect of applying oil has to be seen to be believed as the colour of the veneers jump out at you. Excess oil was removed with a cloth and the cabinet was left alone for a full day to let the oil dry. Stain was not used. Four coats of button shellac were then applied using an artist’s fan brush letting each coat dry for 30 minutes before applying the next coat. The grille was also given four coats of shellac; the shellac was then left to dry overnight.
Fragile grille and ready for hide glue.
The following day the cabinet was well flatted with 400 grit wet or dry abrasive paper used dry then French polishing proper could begin using a traditional polishing rubber made up of a soft cotton outer layer and skin wadding inner. Due to the small size of this set the polishing rubber could only be used for short periods at a time before the surface became unworkable and had to be left alone to dry. I never use oil to lubricate the rubber preferring to use patience and a bit more time to achieve good results. After two days of using the rubber the cabinet was well worked up with shellac and put to one side for a week in a warm place to let the shellac harden.
With the shellac hardened burnishing cream was used to produce a glass like finish. Given the fragile state of the grille, no further work was attempted to improve on the four brush coats of shellac, one break was one too many. The final job was to fully assemble the set and stand back to admire it. It’s a pretty little set and my wife Bronwyn soon claimed it, finding a home for it in our front room.
Bronwyn found it a home.
I still have a number of abused sets under the bungalow to restore and hope people keep snipping leads as I’m getting a nice collection together. I think Henry would have been pleased with the result.
Kind regards, Col.
Happiness is a wreck of a cabinet to restore.
