14-03-2011, 04:28 PM
Hi,
Many thanks for the kind comments Rob; Jamie and Mark they are much appreciated. I improve a bit more with each French polish job I do and at first found French polishing to be a right pain but with practice I've settled down and now find the process to be therapeutic; I try to make each cabinet restoration better than the last and the harder the restoration the bigger the buzz and satisfaction once it is completed.
Here is the story of the chassis restoration of this Philco 84B and it was a nightmare!!
Having successfully restored the cabinet I started the restoration of this Philco 84B chassis on 5 January 2008. Being only a four valver it should have been an easy project to complete. The chassis whilst looking rough was very original apart from two electrolytics which had been soldered directly to the original can. This was going to be a strip to the bare chassis but before doing so I decided to get it working first. It was a simple matter to replace the capacitors which were encased in Bakelite blocks. Each block was removed in turn, heated with a hair drier and the originals pulled free having snipped the leads at the tags. The tags were then cleaned and new modern capacitors were installed and soldered in place checking connections against the circuit diagram which had been a free download from Nostalgia Air. The original electrolytic can was removed and polished then it was cut near its base allowing the innards to be removed allowing new modern electrolytics to be inserted. Most of the resistors were well out of specification so were replaced with modern components. A new mains lead and plug fused at 3A was fitted ensuring the live was broken by the on/off switch. The speaker needed a recone so couldn’t be used and as it contained the field winding a heavy duty 960 ohms resistor was installed to replace the winding allowing the chassis to be connected to the workshop permanent magnet speaker.
[attachment=259]
Rough but original.
The mains transformer was wired for 115 volt use only so to put some power into it a Variac was used winding the voltage up slowly. At 80 volts nothing was happening, this was due to an open circuit wire wound resistor, No.30 on the diagram. The resistor was replaced then again power was applied but now there was signs of life, as the set wasn’t showing any stress voltage was increased to the full 115 volts. Stations could be tuned in but on low volume only with a loud hum. The low volume was traced to No17 compensator (trimmer), its fibre adjusting nut had worked loose in transit. One of the Philco websites gave the answer to the hum. One of the eyelets used to secure the screening can’s base and No.2 valve holder to chassis also has a ring connector attached to it. This ring connector is prone to coming loose as it had in this case; touching it with a screwdriver totally cleared the hum. It’s always wonderful to hear a set burst into life for the first time in many years and this Philco sounded well. Power was left on for a couple of hours to let it warm up before switching off.
[attachment=260]
Chassis fully stripped.
I had done one full chassis strip previously which took many hours to accomplish. To make life easier this time, the components above chassis were marked and noted with sketches before removing but leaving the three tuning coils still connected as they could be pulled through from below chassis with care. The eyelet securing the first tuning can was drilled and an attempt was made to remove the can but it refused to lift clear? Tipping the chassis over there were no other obvious means of it being secured which was a bit of a puzzle. The eyelets were then drilled from the other two cans and all three cans could then be lifted clear, they were spot welded together. The aerial and oscillator transformers looked in good clean condition but I was amazed at the condition of the IF transformer, it looked like something out of a horror movie, it was covered with a coating of what looked like crystallized ginger and spiders webs. The rest of the components were released and removed as one complete assembly taking a lot of care not to damage the tuning coils as they were withdrawn, paper had been wrapped around these coils securing it with rubber bands to be on the safe side. This assembly was placed out of harms way then a start was made at rubbing down the chassis with abrasive paper, 60 grit paper was used for speed to remove the deep rust patches leaving a bright metal chassis ready for painting. The weather was terrible as usual, torrential rain, high winds with much flooding leaving many people homeless. The chassis was placed in a plastic bag to keep it dry then carried into the garage where it was sprayed with grey undercoat using a spray can. Whilst the undercoat was drying a trip was made to our local car accessory shop to purchase suitable paint for the top coat. Looking at the racks of spray cans the silvers didn’t look right. Undecided which colour to choose I was looking out of the window at the rain lashing down which made my mind up. I colour matched the sky and chose Rover Stratos; a dark grey. With the grey gloss applied the chassis was left alone for a few days in a warm place to let the paint harden.
[attachment=261]
Problem cans
The newly painted chassis looked superb and not wanting to scratch it a tea towel was placed under it on the bench. The IF transformer was sprayed with WD 40 and wiped dry with a paper towel, then it was very gently scraped with a sharp craft knife to remove most of the rough surface which turned out to be wax? The rest of the components were sprayed with WD 40 and wiped dry improving their appearance a great deal then the whole assembly was re-fitted to the chassis, this part of the job went very quickly taking care once again not to damage the coils. New brass eyelets had been purchased from DPT in Rochdale at a very reasonable cost of £14inc. for 1,000. (Minimum order £10). The eyelets were 1/8” x ¼”. I also purchased 200 4BA brass round head screws ½” long together with brass nuts, £18 locally, and for good measure purchased 500 1/8” x 5/16” copper dome head semi tubular rivets, £41inc. This selection will last a lifetime. Setting the eyelets wasn’t as easy as expected; the depth of the chassis, the screening can holder and the fragile coils compounded the problem. After a great deal of thought a pair of ¼” dia. x 6”long silver steel punches were turned in the engineering lathe. The punches were then mounted in the drill press ensuring perfect alignment, each eyelet was fitted from above the chassis then the chassis was tipped over locating the eyelet on the bottom punch and the top punch was used to set the eyelet. This worked extremely well and made a very neat job. The mains transformer and screening can were painted and the tuning gang was cleaned using wire wool. The tuning gang was blown off with an air line and its bearings lubricated before fitting. New extended leads were fitted to connect the output transformer which was sitting on the bench and also to the workshop speaker.
[attachment=262]
Sum of parts.
By now I was very pleased, the cabinet and chassis had come up exceedingly well; all that was now needed was to switch on then put the chassis back into the cabinet adding yet another beautiful set to my collection, life couldn’t be better. The chassis burst my bubble big style by declaring a full twelve day war on me. At switch on it refused to talk to me. Thinking the fault would be something simple three days were spent checking connections and components without any luck whatsoever. I contacted Gerry at www.crowthornetubes.com to purchase a spare No.77 valve and explained the problem. Gerry was very kind and replied with a number of suggestions then followed up with a list of very useful websites that contain masses of Philco information. Much time was spent surfing these sites for problems with the 84B. The ring terminal previously mentioned turned up a few times as did a common problem with the tuning coils going open circuit in particular the oscillator coil. A mod was suggested to exchange the No.6 4meg resistor for a 2meg. All three coil units were removed and the aerial tuning primary coil had gone open circuit. Fortunately the primary winding is on the outside and only a few turns of wire are involved making rewinding very easy. Armed with the new information I knew the insulation between the windings was prone to failure causing all sorts of problems so replaced this at the same time. Following the information to the letter I then immersed the entire coil in hot paraffin wax for half a minute, withdrew it and let it dry. Now with the pan of wax cooling the coil was dipped a second time to seal the primary winding with a heavy coat of wax which completed the job. This looked so good and was so easy to do that I decided to rewind the oscillator primary whilst it was on the bench. The oscillator primary has 15 turns and the aerial primary has 21 turns of enameled copper wire. 0.006” thick, (6 thou.). Measured over the enamel. The solder tags were cleaned of wax and the coils were soon refitted to the chassis. At switch on all the stations came in very clear but on low volume? I drilled out the new eyelet on No.2 valve and replaced it with a 4BA brass screw and nut checking for continuity to chassis. The set remained obstinate.
[attachment=263]
Horror movie item.
I then e-mailed my friend Martin Scobie www.marie34.freeserve.co.uk for advice. Martin spent a lot of time e-mailing suggestions and information on how to use the signal generator and oscilloscope to to try to isolate the problem. I spent ages but couldn’t get any sense out of the chassis using the generator and scope and by now was getting a bit fed up with the multitude of leads strewn across the bench so decided to have a go at powering the set from the 240V mains supply direct, at least this would get the Variac off the bench. During all this work I had purchased 26 2.2uF 275VAC Class X2 capacitors from eBay at a very good price of £1 for two. I didn’t want to rewind the mains transformer as it was highly likely the new windings would not fit the laminations but wanted to retain it if possible to offer transformer isolation to the chassis? I had used capacitor droppers before to replace resistive line cords and wondered if it was possible to add a dropper in series between the on/off switch and the transformer using the Variac to determine the required capacitance. I’d never seen this done before but knew the dropper would only work into a resistive load and as the primary of the transformer was resistive decided there was nothing to lose. I tried a single 2.2uF class X2 starting at zero volts on the Variac and was pleased to get low voltage readings on the chassis with the Variac at maximum so added another 2.2uF in parallel this brought the voltage up much higher and with a pair of 0.47uF class X2 added was absolutely delighted to read 6V on the heaters with 112V on the transformer. This proved a very simple, cheap but effective way to convert this chassis to 240V supply retaining the original transformer. The dropper was encased in heat shrink sleeving and installed below chassis in the bottom right hand corner securing it with a spring clip. This cheered me up a lot and got the Variac off the bench. What now followed was a nightmare, days were spent checking and double checking components, the valves were pulled and tested, all the resistors and capacitors were ok as was the wiring? I pulled the oscillator coil off, swapped the primary leads making a mess of the good work to no effect. This was by now testing my patience to the limit; it’s a simple set so why was it giving me so much grief? I was awake at nights thinking about it and couldn’t settle as it was on my mind all the time. The weather was lousy, whilst I was trying to listen for signals the wind was howling so much that I had to connected the earphones up, it was very dark with hail, snow and a lot of frost, this was supposed to be enjoyable.
[attachment=264] [attachment=265]
Chassis repainted. Rewound coils.
During all this I was gaining a lot of much needed experience, I was surfing the web, Gerry and Martin were both wonderful and I was reading. In one of the books, the section on oscillators gave profound advice insomuch that if the two coils were considered to be connected as one; the start of the primary would connect to the anode with the finish of the secondary connected to the following grid. With this information the aerial and oscillator coils were once again removed making me wish that they were secured with zips by now. I stripped both primaries ignoring all my previous notes and rewound both. Full of hope I switched on but now had a totally mute set so at least I had now really upset it!! Studying the circuit diagram in bed for the umpteenth time I found my mistake with the coils. I had taken the start of the primaries in each case as connected per the circuit diagram, what I should have done was to use the chassis tag in each case as the start with the other end being the anode and aerial connections. By now I knew the connections off by heart so removed the coils in the knowledge that this would be the last time and rewound the primaries. This time I took a lot of time and with the primary windings and insulation removed both the aerial and oscillator coils were given a good soak in hot wax sealing the secondary windings. With the new primaries wound the coils were dipped in wax as before and then fitted to the chassis. I found a rubber band to be a great help in holding the insulation in place whilst winding. The set still refused to work. At this point it’s a good job that a sledge hammer wasn’t to hand or I would have surely destroyed this chassis and taken up knitting as a hobby.
[attachment=266] [attachment=267]
Eyelet punch. On test.
Staring in disbelief at this chassis smirking at me on the bench I concluded that I had gone as far as possible and all the components on the chassis were tested ok and connected correctly. In desperation I then swapped the output transformer primary connections and was filled with deep emotion as the set almost blew me off the chair with output. What a total idiot I felt. Whilst installing the three new output transformer leads; I had soldered the ends below chassis and as the leads were all the same colour used the multimeter to check each for continuity before connecting to the output transformer, regarding this repair the most important word that will forever live with me is “feedback”. I was so certain that the output side of the set was correct that I didn’t consider it to be at fault, after all the set was running on low volume so I wrongly assumed everything was connected ok. I can now use Martin’s excellent advice and have a go at alignment for the first time, it’s aligned by ear as I write and is a good performer. It was worth it in the end.
Suppliers and websites used as follows.
[attachment=268]
Worth the effort.
Eyelets; http://www.dtpsupplies.com
Rivets; http://www.sapphireproducts.co.uk
BA screws and nuts; Tele; 01484 518798. (Danlett; Huddersfield).
Websites;
http://www.philcoradio.com
http://www.philcorepairbench.com
http://nostalgiaair.org
These basket cases are so rewarding to restore; they are full of problems and drive me mad at times; I prefer cabinetwork to chassis work and I’m learning all the time; this is such a wonderful hobby and costs very little money wise considering the personal enjoyment and interest they afford me. This Philco is a welcome addition to my growing collection.
Kind regards, Col.
Many thanks for the kind comments Rob; Jamie and Mark they are much appreciated. I improve a bit more with each French polish job I do and at first found French polishing to be a right pain but with practice I've settled down and now find the process to be therapeutic; I try to make each cabinet restoration better than the last and the harder the restoration the bigger the buzz and satisfaction once it is completed.
Here is the story of the chassis restoration of this Philco 84B and it was a nightmare!!
Having successfully restored the cabinet I started the restoration of this Philco 84B chassis on 5 January 2008. Being only a four valver it should have been an easy project to complete. The chassis whilst looking rough was very original apart from two electrolytics which had been soldered directly to the original can. This was going to be a strip to the bare chassis but before doing so I decided to get it working first. It was a simple matter to replace the capacitors which were encased in Bakelite blocks. Each block was removed in turn, heated with a hair drier and the originals pulled free having snipped the leads at the tags. The tags were then cleaned and new modern capacitors were installed and soldered in place checking connections against the circuit diagram which had been a free download from Nostalgia Air. The original electrolytic can was removed and polished then it was cut near its base allowing the innards to be removed allowing new modern electrolytics to be inserted. Most of the resistors were well out of specification so were replaced with modern components. A new mains lead and plug fused at 3A was fitted ensuring the live was broken by the on/off switch. The speaker needed a recone so couldn’t be used and as it contained the field winding a heavy duty 960 ohms resistor was installed to replace the winding allowing the chassis to be connected to the workshop permanent magnet speaker.
[attachment=259]
Rough but original.
The mains transformer was wired for 115 volt use only so to put some power into it a Variac was used winding the voltage up slowly. At 80 volts nothing was happening, this was due to an open circuit wire wound resistor, No.30 on the diagram. The resistor was replaced then again power was applied but now there was signs of life, as the set wasn’t showing any stress voltage was increased to the full 115 volts. Stations could be tuned in but on low volume only with a loud hum. The low volume was traced to No17 compensator (trimmer), its fibre adjusting nut had worked loose in transit. One of the Philco websites gave the answer to the hum. One of the eyelets used to secure the screening can’s base and No.2 valve holder to chassis also has a ring connector attached to it. This ring connector is prone to coming loose as it had in this case; touching it with a screwdriver totally cleared the hum. It’s always wonderful to hear a set burst into life for the first time in many years and this Philco sounded well. Power was left on for a couple of hours to let it warm up before switching off.
[attachment=260]
Chassis fully stripped.
I had done one full chassis strip previously which took many hours to accomplish. To make life easier this time, the components above chassis were marked and noted with sketches before removing but leaving the three tuning coils still connected as they could be pulled through from below chassis with care. The eyelet securing the first tuning can was drilled and an attempt was made to remove the can but it refused to lift clear? Tipping the chassis over there were no other obvious means of it being secured which was a bit of a puzzle. The eyelets were then drilled from the other two cans and all three cans could then be lifted clear, they were spot welded together. The aerial and oscillator transformers looked in good clean condition but I was amazed at the condition of the IF transformer, it looked like something out of a horror movie, it was covered with a coating of what looked like crystallized ginger and spiders webs. The rest of the components were released and removed as one complete assembly taking a lot of care not to damage the tuning coils as they were withdrawn, paper had been wrapped around these coils securing it with rubber bands to be on the safe side. This assembly was placed out of harms way then a start was made at rubbing down the chassis with abrasive paper, 60 grit paper was used for speed to remove the deep rust patches leaving a bright metal chassis ready for painting. The weather was terrible as usual, torrential rain, high winds with much flooding leaving many people homeless. The chassis was placed in a plastic bag to keep it dry then carried into the garage where it was sprayed with grey undercoat using a spray can. Whilst the undercoat was drying a trip was made to our local car accessory shop to purchase suitable paint for the top coat. Looking at the racks of spray cans the silvers didn’t look right. Undecided which colour to choose I was looking out of the window at the rain lashing down which made my mind up. I colour matched the sky and chose Rover Stratos; a dark grey. With the grey gloss applied the chassis was left alone for a few days in a warm place to let the paint harden.
[attachment=261]
Problem cans
The newly painted chassis looked superb and not wanting to scratch it a tea towel was placed under it on the bench. The IF transformer was sprayed with WD 40 and wiped dry with a paper towel, then it was very gently scraped with a sharp craft knife to remove most of the rough surface which turned out to be wax? The rest of the components were sprayed with WD 40 and wiped dry improving their appearance a great deal then the whole assembly was re-fitted to the chassis, this part of the job went very quickly taking care once again not to damage the coils. New brass eyelets had been purchased from DPT in Rochdale at a very reasonable cost of £14inc. for 1,000. (Minimum order £10). The eyelets were 1/8” x ¼”. I also purchased 200 4BA brass round head screws ½” long together with brass nuts, £18 locally, and for good measure purchased 500 1/8” x 5/16” copper dome head semi tubular rivets, £41inc. This selection will last a lifetime. Setting the eyelets wasn’t as easy as expected; the depth of the chassis, the screening can holder and the fragile coils compounded the problem. After a great deal of thought a pair of ¼” dia. x 6”long silver steel punches were turned in the engineering lathe. The punches were then mounted in the drill press ensuring perfect alignment, each eyelet was fitted from above the chassis then the chassis was tipped over locating the eyelet on the bottom punch and the top punch was used to set the eyelet. This worked extremely well and made a very neat job. The mains transformer and screening can were painted and the tuning gang was cleaned using wire wool. The tuning gang was blown off with an air line and its bearings lubricated before fitting. New extended leads were fitted to connect the output transformer which was sitting on the bench and also to the workshop speaker.
[attachment=262]
Sum of parts.
By now I was very pleased, the cabinet and chassis had come up exceedingly well; all that was now needed was to switch on then put the chassis back into the cabinet adding yet another beautiful set to my collection, life couldn’t be better. The chassis burst my bubble big style by declaring a full twelve day war on me. At switch on it refused to talk to me. Thinking the fault would be something simple three days were spent checking connections and components without any luck whatsoever. I contacted Gerry at www.crowthornetubes.com to purchase a spare No.77 valve and explained the problem. Gerry was very kind and replied with a number of suggestions then followed up with a list of very useful websites that contain masses of Philco information. Much time was spent surfing these sites for problems with the 84B. The ring terminal previously mentioned turned up a few times as did a common problem with the tuning coils going open circuit in particular the oscillator coil. A mod was suggested to exchange the No.6 4meg resistor for a 2meg. All three coil units were removed and the aerial tuning primary coil had gone open circuit. Fortunately the primary winding is on the outside and only a few turns of wire are involved making rewinding very easy. Armed with the new information I knew the insulation between the windings was prone to failure causing all sorts of problems so replaced this at the same time. Following the information to the letter I then immersed the entire coil in hot paraffin wax for half a minute, withdrew it and let it dry. Now with the pan of wax cooling the coil was dipped a second time to seal the primary winding with a heavy coat of wax which completed the job. This looked so good and was so easy to do that I decided to rewind the oscillator primary whilst it was on the bench. The oscillator primary has 15 turns and the aerial primary has 21 turns of enameled copper wire. 0.006” thick, (6 thou.). Measured over the enamel. The solder tags were cleaned of wax and the coils were soon refitted to the chassis. At switch on all the stations came in very clear but on low volume? I drilled out the new eyelet on No.2 valve and replaced it with a 4BA brass screw and nut checking for continuity to chassis. The set remained obstinate.
[attachment=263]
Horror movie item.
I then e-mailed my friend Martin Scobie www.marie34.freeserve.co.uk for advice. Martin spent a lot of time e-mailing suggestions and information on how to use the signal generator and oscilloscope to to try to isolate the problem. I spent ages but couldn’t get any sense out of the chassis using the generator and scope and by now was getting a bit fed up with the multitude of leads strewn across the bench so decided to have a go at powering the set from the 240V mains supply direct, at least this would get the Variac off the bench. During all this work I had purchased 26 2.2uF 275VAC Class X2 capacitors from eBay at a very good price of £1 for two. I didn’t want to rewind the mains transformer as it was highly likely the new windings would not fit the laminations but wanted to retain it if possible to offer transformer isolation to the chassis? I had used capacitor droppers before to replace resistive line cords and wondered if it was possible to add a dropper in series between the on/off switch and the transformer using the Variac to determine the required capacitance. I’d never seen this done before but knew the dropper would only work into a resistive load and as the primary of the transformer was resistive decided there was nothing to lose. I tried a single 2.2uF class X2 starting at zero volts on the Variac and was pleased to get low voltage readings on the chassis with the Variac at maximum so added another 2.2uF in parallel this brought the voltage up much higher and with a pair of 0.47uF class X2 added was absolutely delighted to read 6V on the heaters with 112V on the transformer. This proved a very simple, cheap but effective way to convert this chassis to 240V supply retaining the original transformer. The dropper was encased in heat shrink sleeving and installed below chassis in the bottom right hand corner securing it with a spring clip. This cheered me up a lot and got the Variac off the bench. What now followed was a nightmare, days were spent checking and double checking components, the valves were pulled and tested, all the resistors and capacitors were ok as was the wiring? I pulled the oscillator coil off, swapped the primary leads making a mess of the good work to no effect. This was by now testing my patience to the limit; it’s a simple set so why was it giving me so much grief? I was awake at nights thinking about it and couldn’t settle as it was on my mind all the time. The weather was lousy, whilst I was trying to listen for signals the wind was howling so much that I had to connected the earphones up, it was very dark with hail, snow and a lot of frost, this was supposed to be enjoyable.
[attachment=264] [attachment=265]
Chassis repainted. Rewound coils.
During all this I was gaining a lot of much needed experience, I was surfing the web, Gerry and Martin were both wonderful and I was reading. In one of the books, the section on oscillators gave profound advice insomuch that if the two coils were considered to be connected as one; the start of the primary would connect to the anode with the finish of the secondary connected to the following grid. With this information the aerial and oscillator coils were once again removed making me wish that they were secured with zips by now. I stripped both primaries ignoring all my previous notes and rewound both. Full of hope I switched on but now had a totally mute set so at least I had now really upset it!! Studying the circuit diagram in bed for the umpteenth time I found my mistake with the coils. I had taken the start of the primaries in each case as connected per the circuit diagram, what I should have done was to use the chassis tag in each case as the start with the other end being the anode and aerial connections. By now I knew the connections off by heart so removed the coils in the knowledge that this would be the last time and rewound the primaries. This time I took a lot of time and with the primary windings and insulation removed both the aerial and oscillator coils were given a good soak in hot wax sealing the secondary windings. With the new primaries wound the coils were dipped in wax as before and then fitted to the chassis. I found a rubber band to be a great help in holding the insulation in place whilst winding. The set still refused to work. At this point it’s a good job that a sledge hammer wasn’t to hand or I would have surely destroyed this chassis and taken up knitting as a hobby.
[attachment=266] [attachment=267]
Eyelet punch. On test.
Staring in disbelief at this chassis smirking at me on the bench I concluded that I had gone as far as possible and all the components on the chassis were tested ok and connected correctly. In desperation I then swapped the output transformer primary connections and was filled with deep emotion as the set almost blew me off the chair with output. What a total idiot I felt. Whilst installing the three new output transformer leads; I had soldered the ends below chassis and as the leads were all the same colour used the multimeter to check each for continuity before connecting to the output transformer, regarding this repair the most important word that will forever live with me is “feedback”. I was so certain that the output side of the set was correct that I didn’t consider it to be at fault, after all the set was running on low volume so I wrongly assumed everything was connected ok. I can now use Martin’s excellent advice and have a go at alignment for the first time, it’s aligned by ear as I write and is a good performer. It was worth it in the end.
Suppliers and websites used as follows.
[attachment=268]
Worth the effort.
Eyelets; http://www.dtpsupplies.com
Rivets; http://www.sapphireproducts.co.uk
BA screws and nuts; Tele; 01484 518798. (Danlett; Huddersfield).
Websites;
http://www.philcoradio.com
http://www.philcorepairbench.com
http://nostalgiaair.org
These basket cases are so rewarding to restore; they are full of problems and drive me mad at times; I prefer cabinetwork to chassis work and I’m learning all the time; this is such a wonderful hobby and costs very little money wise considering the personal enjoyment and interest they afford me. This Philco is a welcome addition to my growing collection.
Kind regards, Col.
