I'm either stupid or a sucker for punishment.

[boater sam]

Restless after the fire caused by the last GEC incendiary bomb to get back into fixing radios, top of the pile is a Philips BG400/15 AM radio. Dates from 1950 so a tad younger than me! 3 wavebands, normal rimlock B8A E40 series valve line up. This has the problematical tapped volume potentiometer, hope its usable or repairable.
I will be working off the Trader sheet mainly, number 973, as I cannot make any sense of the wave change switches on any of Philips' works sheets. The trader sheets are much better in this regard and the layout of the circuits is more what like I prefer to read.
The cabinet is bakelite, fake wood grain and paint and very scratched and dirty but seems uncracked or dinged. May clean up but otherwise it could be repainted.
Its the usual horrendously dirty set but seems fairly unmolested, obvious at first glance is the cut off mains cable, surprisingly brown and blue flex so that's not original. The back is missing which probably accounts for the builder's brick rubble inside the cabinet in front of the chassis. An odd rubber bush lying amid the aerial coil cans is not a part of the set I reckon.
All the valves are in and look whole. All the fragile clear knobs are on, but the wavechange switch is seized solid. These are the ones with through spindle grub screws, special control shafts. The detachable tuning scale is stuck fast in the slot at the top of the cabinet but the pointer moves a bit when the tuning knob is carefully turned, being extremely careful not to wreck the tuning drives, there is one for the pointer and another nightmare one for the condenser, typical of Philips of this period.
Mains voltage selector plug is in the 245v position. Nothing looks burnt, mains transformer is still tar covered. Briefly sticking some power on via the isolation  and lamp limiter produced absolutely nothing, the QMB switch on the volume control sounds reasonable and the thermal switch on the mains transformer looks OK so it will have to be a chassis out to make any progress.
The outer 2 larger knobs were released once the grub screws were removed but the inner 2 small ones had totally seized screws so its dose with oil and leave it for the night.
Pictures next time, hands too filthy now to use the camera.
Sam.

[Diabolical Artificer]

It's like falling off an oss or having a bike smash Sam, one has to get back on.

Andy.

[boater sam]

Ok, back in the saddle so to speak.
Pictures of the start.

   
   

I did say it was dirty.

 Carefully levered the glass scale out to find rubble underneath and stuck between the glass and the felt backing, ouch! The glass has a bottom corner chipped but it won't show when it is in, the screen printing on the back remarkably is OK despite the rocks.

   

The overnight oil did the business, with a freshly ground screwdriver the remaining two knob grub screws submitted and the knobs are all off.
To remove the chassis the tuning pointer carriage has to be disconnected from the wire drive, the bottom foil connection has to be taken off the chassis, speaker disconnected and 4 bolts underneath removed.

   

Mmmm, plenty more rubble under the chassis.

   

Time to clean the cabinet out and find a metal piece, U shaped, in the rubbish. Is it part of the set?

More in next post.

[boater sam]

Chassis out, time to try to remove the dust and debris.
       

Looks a bit better cleaned off, its dusty even underneath. Lots of the usual black pitch capacitors, all suspect of course. The reservoir capacitor has leaked from top and bottom, that must be duff.

   

A mix of valves. a Mazda mixer, Philco rectifier the rest are Mullards so its had some valves in its life yet the speaker wires seem never to have been unsoldered.
Continuity on the mains through the QMB mains switch, but my error, the thermal fuse on the transformer is sprung open. The transformer is OK, 95 ohm on the primary. So is the bit of metal I found part of the fuse link?
The fuse hook attached to the winding had a diabolo shaped piece stuck in it, must be part of the fuse assembly but I can't see how it goes together.
     

What am I missing? There must be some part missing, not found any part that would melt on overheat and I can't see how these two bits fit together.    
Can anyone help me with how this fuse/switch goes together please? Do I have all the bits?

Output transformer checks out OK, Hung a speaker on, I fitted a brass washer on the two hooks where the thermal fuse should be and applied some power. Rectifier and output valves light up, HT is almost nonexistent due no doubt  to duff reservoir and smoothing capacitors.
Removing the cans I find the reservoir can is insulated from the chassis, not according to the Trader sheet but it is on the Philips sheet so I think I will work off that from now on, Trader has been known to make mistakes when creating their sheets from an actual set. Its unusual to have the reservoir can not connected to chassis, must be part of the biasing for the valves.

Hung a couple of 47uf 250v caps on instead of the cans, the HT is now up, 287v so we have progress.  No sound but its early days yet. Eyes tired now ( workshop still has the acrid smokey stink ) so call it a day, I will do a proper restuff of the cans tomorrow. Should be able to get at least the output working soon.

[boater sam]

Chassis out, time to try to remove the dust and debris.
[attachment=19032][attachment=19033]

Looks a bit better cleaned off, its dusty even underneath. Lots of the usual black pitch capacitors, all suspect of course. The reservoir capacitor has leaked from top and bottom, that must be duff.

[attachment=19034]

A mix of valves. a Mazda mixer, Philco rectifier the rest are Mullards so its had some valves in its life yet the speaker wires seem never to have been unsoldered.
Continuity on the mains through the QMB mains switch, but my error, the thermal fuse on the transformer is sprung open. The transformer is OK, 95 ohm on the primary. So is the bit of metal I found part of the fuse link?
The fuse hook attached to the winding had a diabolo shaped piece stuck in it, must be part of the fuse assembly but I can't see how it goes together.
 [attachment=19035]

What am I missing? There must be some part missing, not found any part that would melt on overheat and I can't see how these two bits fit together.[attachment=19036]
Can anyone help me with how this fuse/switch goes together please? Do I have all the bits?

Output transformer checks out OK, Hung a speaker on, I fitted a brass washer on the two hooks where the thermal fuse should be and applied some power. Rectifier and output valves light up, HT is almost nonexistent due no doubt  to duff reservoir and smoothing capacitors.
Removing the cans I find the reservoir can is insulated from the chassis, not according to the Trader sheet but it is on the Philips sheet so I think I will work off that from now on, Trader has been known to make mistakes when creating their sheets from an actual set. Its unusual to have the reservoir can not connected to chassis, must be part of the biasing for the valves.

Hung a couple of 47uf 250v caps on instead of the cans, the HT is now up, 287v so we have progress.  No sound but its early days yet. Eyes tired now ( workshop still has the acrid smokey stink ) so call it a day, I will do a proper restuff of the cans tomorrow. Should be able to get at least the output working soon.

[boater sam]

Getting bogged down in boaty stuff this week, not getting much time in the workshop.
I have restuffed the wet electrolytics though.
Its the first time I have done any of these and I was fascinated by the construction.

Basically an aluminium can with a vent on a top cap under a tin cover, red rubber cap on top. Plastic thread on the bottom with a brass fixing nut.
But inside 2 sets of concentric aluminium rings with slots in them,one above the other. immersed originally in an electrolyte which is probably not very nice. 
The reservoir capacitor was almost totally dried out but the smoother had not leaked and was still full.
I cut the tops off with a hacksaw and released the riveted bottom connection, pulled all the guts out, washed the tubes and fitted 47uf 450v capacitors. 
I poked the + lead through the bottom as the connection and connected the - lead to a folded piece of tinplate that was a tight springy fit inside the tube to make the negative connection.

           

With the tin cap and rubber refitted they look original.

I also replaced the -HT smoothing capacitor, C3 on the Philips sheet, 100uf @12v with a new 25v item, it was no longer a capacitor, reading very high on the Chinese magic box due to leakage.

Powering up I have good HT but no sound. Injecting a tone into the G1 of the EL41 V4 gets a good output but nothing if injected into the slider of the volume control or the phono socket. The EBC41 seems to be OK so I will have to trace back and find why, the combined tone and phono switch is in this circuit but it looks OK. I am suspicious of the tapped volume control, they are known to be unreliable and its a special item difficult to find a replacement for.

[boater sam]

It was so simple really.

HT to the EL41 only! 

The smoothing resistor is open circuit. So high HT because only the output transformer was getting anything. It is fed from the reservoir.
The modulation capacitor is cooking so replaced, 0.022uf paper/pitch jobby.

Lashed in 1k2 resistor, we have stations and a few whistles with much distortion but its progress. HT is a little lower than the Trader sheet suggests but then there are still plenty of pitch capacitors still in there. And the dairy was running so the mains is low @230v

Then dead again, the Philco EZ40 rectifier decided its time was up, the heater went O/C for no particular reason I can see.
Spare popped in and we are back with radio 4.
Volume control works, phew!

Looking for a reason for the failed 5w resistor and the tripped safety fuse link on the transformer but there is nothing obvious. Nothing is cooking in the short time I have run it for so far. I am guessing it was due to the failed electrolytics draining the HT.

[Refugee]

I have got A Phillips AC bridge that has a thermal trip with a coil spring and the same U shaped bit and the same "slug".
Yours has a leaf spring.
The "slug" fits between the U shape and is soldered in there with the spring pulling on it so that the "slug" comes out if it gets hot.
There should be a thermally conductive bit that the "slug" is in close contact with that contacts the core of the transformer. I can't see it in your photo.

[Refugee]

I have had a better look at your photo. The thermally conductive bit is visible and will have the end of the primary connected to it in the same way as mine is.
The slug hooks onto the bit that is sticking out of the winding and if that gets hot it melts the solder holding the slug into the U shape so that the leaf spring pulls the power off. Mains is connected to the leaf spring.

[boater sam]

I have got A Phillips AC bridge that has a thermal trip with a coil spring and the same U shaped bit and the same "slug".
Yours has a leaf spring.
The "slug" fits between the U shape and is soldered in there with the spring pulling on it so that the "slug" comes out if it gets hot.
There should be a thermally conductive bit that the "slug" is in close contact with that contacts the core of the transformer. I can't see it in your photo.

Brilliant, thanks.

The slug, diablo shaped was stuck inside the hook on the winding when I found it, like yours.
How the u shape was attached to the spring I cannot fathom. But that is a simple problem to solve.
There is no spare low melt solder on any part but if they are still tinned they should solder back together.

As a last resort I will fit a thermal fuse to the winding but it would be better to get the original bits refitted.

Thank you for the post and picture, worth a thousand words.
Sam.