Philips BG400/15: I...
 
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Philips BG400/15: I must be stupid but it is only a hobby

 
Boater Sam
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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.

Sam.

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Topic starter Posted : 07/09/2019 8:56 pm
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Boater Sam
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Ok, back in the saddle so to speak, I carefully levered the glass scale out to find rubble underneath also stuck between the glass and the felt backing. Ouch! The glass has a bottom corner chipped off but it won't show when it is in place, the screen printing on the back is remarkably OK despite the rubble. Some overnight oil did the business in assisting removal of the knobs, With a freshly ground screwdriver, the remaining two knob grub screws submitted and the knobs were all off.

To remove the chassis first the tuning pointer carriage has to be disconnected from the wire drive. Then the bottom foil connection has to be taken off the chassis, speaker disconnected and 4 bolts underneath removed. Once done this revealed plenty more rubble under the chassis so it was time to clean the cabinet out. It 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. Found a metal piece in  amongst all the rubbish, its U-shaped, is it part of the set?

The set has a mix of valves installed, 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. There is 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 measuring 95ohm 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?

phil400A

The 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. The rectifier and output valves light up, H.T. 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 H.T. is now up to 287V so we have progress. No sound but its early days yet. Eyes tired now (workshop still has the acrid smokey stink) so I will call it a day. I will do a proper re-stuff of the cans tomorrow,  should be able to get at least the output working soon.

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Topic starter Posted : 09/09/2019 7:00 pm
Nuvistor
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I had a look in the Philips manual but it just states Z1 for the fuse with a part number, not much help.

There are some photos of transformer fuses in Philips sets in this UKVRRR post.

https://www.vintage-radio.net/forum/showthread.php?t=137366

 

 

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Posted : 10/09/2019 3:37 pm
Boater Sam
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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.

DSCN0278
DSCN0277

 

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.

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Topic starter Posted : 11/09/2019 10:19 am
Boater Sam
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@nuvistor

Thanks Frank but as I am irretrievably banned from UKVRRR I cannot see them!

Sam. 

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Topic starter Posted : 11/09/2019 10:29 am
Cathovisor
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Posted by: @boater-sam

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. 

Borax in solution, I believe. Mostly harmless.

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Posted : 11/09/2019 10:47 am
Boater Sam
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Posted by: @boater-sam

@nuvistor

Thanks Frank but as I am irretrievably banned from UKVRRR I cannot see them!

Sam. 

Sent you a PM Frank.

Sam.

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Topic starter Posted : 11/09/2019 12:05 pm
Nuvistor
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PM replied to, will sort it out tonight.

 

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Posted : 11/09/2019 12:42 pm
crustytv
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Posted by: @boater-sam

 I am irretrievably banned from UKVRRR I cannot see them!

How odd...I'm not a member of UKVRRR so I'm unable to login but I don't need to as UKVRRR unlike GVR, allow guests (non members) to view attachments unrestricted (meaning you don't need an account or be logged in).  As such I can view any photo attached to any post and download any PDF attached to any post.

The only way I could see them stopping you would be a ban on your IP address, in which case renew your IP address (router option) or visit via a free online proxy server unless like VRAT, they also ban proxy access. What happens when you try to view? Do you get an error message?

See below, me viewing as a guest the link Frank posted, absolutely no trouble whatsoever.

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Posted : 11/09/2019 12:49 pm
Boater Sam
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@crustytv

Hi.

I get the 'you are banned' message when trying to view any file or answer to any post.

Paul just won't let me on his forum since his moderator banned me.

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Topic starter Posted : 11/09/2019 1:30 pm
crustytv
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Sam, I highly suspect the problem is because you are still logged in to UKVRRR. If I recall correctly, when a member is banned from UKVRRR, that member can still login but can do nothing.

At some point in the past you probably ticked "remember me" on their login box, therefore every time you visit you are automatically logged back in and all the restrictions kick in. So as I say I suspect you are still logged in and need to logout, so log out! They do have a logout button you know. ? 

Once logged out you will then be viewing as a guest like the rest of us and won't have any trouble viewing photos. I know a number of folk who are banned from UKVRRR, a few are now here, they can all view posts, images and any attachments over there without any trouble. I seriously doubt UKVRRR will have singled you out for a total blockade.

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Posted : 11/09/2019 1:39 pm
sideband
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I suspect that part of the problem is you sometimes log in via the Philippines. I believe that logging on from there sets up alarm bells with some people and the IP address is then blocked.  

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Posted : 11/09/2019 1:46 pm
Terry
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Posted by: @boater-sam

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 ...

Sam, I hadn't looked at the Trader sheet until now but it clearly shows the reservoir and smoothing both returned to the bias rail and not to the chassis! The bias is then developed across R20 and decoupled by C23.

Does the Philips version show the reservoir returned to the bias rail and the smoothing to chassis or has someone replaced the smoothing at some time and 'lost' the insulator?

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Posted : 11/09/2019 1:57 pm
Boater Sam
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Posted by: @crustytv

Sam, I highly suspect the problem is because you are still logged in to UKVRRR. If I recall correctly, when a member is banned from UKVRRR, that member can still login but can do nothing.

At some point in the past you probably ticked "remember me" on their login box, therefore every time you visit you are automatically logged back in and all the restrictions kick in. So as I say I suspect you are still logged in and need to logout, so log out! They do have a logout button you know. ? 

Once logged out you will then be viewing as a guest like the rest of us and won't have any trouble viewing photos. I know a number of folk who are banned from UKVRRR, a few are now here, they can all view posts, images and any attachments over there without any trouble. I seriously doubt UKVRRR will have singled you out for a total blockade.

You are so correct,  thank you.

If I logout and go as a guest I can see the pix, but they only show the same as I have on this set, the contacts already sprung open and no clue as to what held them together.

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Topic starter Posted : 11/09/2019 2:15 pm
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Cathovisor
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I've got one of these sets - would it be helpful if I took a peek at the transformer?

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Posted : 11/09/2019 6:25 pm
Boater Sam
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Posted by: @cathovisor

I've got one of these sets - would it be helpful if I took a peek at the transformer?

Thanks for the offer but thanks to a Golborne member,  Refugee, the correct assembly is revealed and it just remains to work out how the u shaped bit is attached to the leaf spring.

But that is a simple mechanical problem.

Sam

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Topic starter Posted : 11/09/2019 7:59 pm
Boater Sam
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Good to see you on the forum.

Sam

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Topic starter Posted : 11/09/2019 9:04 pm
Boater Sam
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Posted by: @terrykc
Posted by: @boater-sam

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 ...

Sam, I hadn't looked at the Trader sheet until now but it clearly shows the reservoir and smoothing both returned to the bias rail and not to the chassis! The bias is then developed across R20 and decoupled by C23.

Does the Philips version show the reservoir returned to the bias rail and the smoothing to chassis or has someone replaced the smoothing at some time and 'lost' the insulator?

Hi Terry,

Sorry, I missed your post in the melee of access to UKVRRR.

The reservoir neg is to the HT- rail, the smoother neg is to chassis. This agrees with the Philips works sheet. And it works, the -HT is bias for valves. So the Trader sheet is not a faithful interpretation of the set as found.

Doubt it has ever been changed, the speaker leads had never been unsoldered, they are crimped on before being soldered. Also they would of had to lose the tab washer too and the wire that would have been attached to it, only the reservoir is wired  neg to HT- rail.

Sam.

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Topic starter Posted : 11/09/2019 10:05 pm
sideband
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Posted by: @boater-sam

 

The reservoir neg is to the HT- rail, the smoother neg is to chassis. This agrees with the Philips works sheet. And it works, the -HT is bias for valves.

Philips did that in a lot of their radios. My 274 Superinductance is the same and the -ve bias is tapped of various resistors to feed the RF valves.

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Posted : 12/09/2019 1:50 pm
Boater Sam
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Had the time to replace all the pitch paper capacitors today.

Set works, tunes stations but with bad whistling either side of strong stations and obvious IF oscillation.

A quick valve swap solved nothing so its going to be more complicated than a recap.

Soldered the thermal link back together and hooked it onto both hooks on the transformer, done. Fitted a fresh 3 core mains lead and earthed the chassis, transformer is not distressed, I feel happier with a proper lead and an earth rather than my temporary two core suicide lead.

Oh, and fitted a new light bulb, one of the originals is still working!

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Topic starter Posted : 12/09/2019 5:35 pm