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Old 1st Sep 2015, 10:57 am   #21
Tim
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Default Re: Philips B3G63A

Hi Donald, I never like to blow my own trumpet but I did one of these early this century.............

http://www.vintage-radio.com/recent-...ps-b3g63a.html

Hope fully it will be of some help. I do like these sets, and they are good performers but the valves in the RF stages must be working well.

Quote:
I intend to replace them with new wire, being careful to dress them away from the EL84 and any other hot parts on re-assembly
Very wise as one of the leads on mine had developed an intermittent o/c after the insulation had melted on the OP valve and corrosion had set in. The O/C speaker wire caused the EL84 to become very uncomfortable indeed, (fireworks!) so one to watch. Either tie it down like I did or use heat resisting wires. You could also connect a beefy 100 ohm resistor across the OP TX secondary to avoid losing sleep.............
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Old 1st Sep 2015, 6:54 pm   #22
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Default Re: Philips B3G63A

Hi Donald,
I've not rewired the speaker connections yet, as the cabinet is still off and I am giving that a once-over. It's not too bad, just a few shallow scratches. The old fellow who owned the set had a coal fire, which has made it rather grimey. The knobs and buttons were really awful, but came up a treat when washed in caustic soda soloution.
Speaker cable?well, I will find some suitable wire in the 'reclaimed lenghts of equipment wire' junk-box. It does not have to be anything special as there is no high voltages on the speaker leads, but make sure you have leads long enough to be able to keep them away from hot items as stated in my previous post.
I also intend to fit a mains fuse, as I do to all of my restored sets if there is none fitted..
I must confess that I replace capacitors with whatevet I have that is electrically suitable, regardless of looks if its under the chassis but it has to be equal to or better than the original spec. The only caps I found in need of replacing (apart from the H.T.smoothers) were the two black .015uF ones connected to the tone control. These are the coupling capacitors to the EL84 grid, and were causing a positive voltage to appear on the grid pin of the valve. They looked good on a meter(>20 Mohm), but still were the cause of the positive voltage .I do have a lot of spares, as I was, (and to some extent still am) in the trade from the 1950's onwards, so I tend to use what is to hand, but only if its new or 100% Ok. Good luck with your restoration. Tony
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Old 2nd Sep 2015, 2:08 pm   #23
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Default Re: Philips B3G63A

Hi Tony

Although I will replace the the mains lead with a new 3 core cable I hadn't thought about adding a mains fuse - do you have any details of how to go about that?

While still on the subject of mains leads, what is the recommended fuse for the plug - 1A, 3A or higher?
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Old 2nd Sep 2015, 3:50 pm   #24
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Default Re: Philips B3G63A

Hi Donald,
Regarding the plug fuse, a 3 amp should be Ok, especially if you intend to fit an internal fuse inside the set.
I have found that very often there is nowhere on the chassis top, and the underside too, of many sets to fit a normal fuseholder. I therefore usually use a fuseholder designed for automotive use as in the sketch below. (Setting up for a photo of one is rather a chore.) These are not an approved type for mains use, but have proved quite safe and reliable in use, and require no drilling of the chassis etc. The only constraint is to ensure they are not mounted near a source of heat. I usually put them under the chassis for that reason (cooler). Easy, and cheap to buy from car accessory shops. Wire into the 'live' lead with the "spring" side (You will know what I mean by that when you get one.) to the switch, not to the supply. I usually use an 800m/a anti-surge fuse for this class of set. Tony
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Old 2nd Sep 2015, 3:59 pm   #25
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Default Re: Philips B3G63A

Thanks for the advice Tony - would you secure the in-line fuse holder to the chassis or use something like a cable tie?
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Old 2nd Sep 2015, 9:08 pm   #26
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Default Re: Philips B3G63A

O.k. finally liberated the chassis from the cabinet - disconnected the small earth tag underneath, desoldered the speaker wires and the two core mains cable as they are going to be replaced anyway. Spotted the earth tag on the chassis which is handy when I connect up the new three core mains cable and inline fuse.

Chassis now free and rotated to get my first look underneath - (expletives deleted) what have I done - see attached images!

Where do I start?
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Old 2nd Sep 2015, 9:13 pm   #27
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Default Re: Philips B3G63A

I would start by getting rid of all the dust and muck. A 1" paintbrush and a vacuum cleaner is a good starting point.

Be careful not to damage any fine wires.

Nick.
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Old 2nd Sep 2015, 9:36 pm   #28
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Default Re: Philips B3G63A

Quote:
Originally Posted by DonaldStott View Post
Thanks for the advice Tony - would you secure the in-line fuse holder to the chassis or use something like a cable tie?
Hi Donald,
these fuse carriers are very light in weight, and can be suspended by their wiring, but leave enough slack to enable the fuseholder to be opened in the unlikely event of the fuse having to be replaced. Get one first, and you willl be able to work out how to fix it in place. Usually very easy. By the way, I also replaced the output valve cathode bias cap. with a modern, smaller one which fitted directly across the bias resistor. Makes working around the volume/tone controls much easier, too. Persevere, and you'll get there! Tony
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Old 2nd Sep 2015, 9:46 pm   #29
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Default Re: Philips B3G63A

Thanks Nick and Tony for your ongoing support.

As I'm still finding my way round, which is the output valve cathode bias capacitor I.e which C number on the Schematic?
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Old 3rd Sep 2015, 9:11 am   #30
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Default Re: Philips B3G63A

Hi Howard,
The resistor and capacitor numbers will depend on which service sheet you are using. I am using the Trader sheet Nr1374. The manufacturer's sheet part designations will be different.
On the Trader sheet, they are labelled as R33 and C65 respectively. They both have one end connected to pin 3 of V6, the EL84 valve. The cap is that large pinky one in your photo, lurking near the vol/tone controls. The resistor is 150 Ohm and is worth measuring with an ohmmeter as it's being of the correct value is important to the comfortable operation of the EL84. A replacement shoud be at least 1Watt rating. It is likely to be Ok, I think. Ensure the capacitor is connected with the negative end to chassis. If the VHF is poor, experiment with substituting an EF183 or EF184 for either/ both of the EF80s. No modifications needed when trying that. Tony.
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Old 3rd Sep 2015, 12:21 pm   #31
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Default Re: Philips B3G63A

That's good news Tony as I'm working from Trader sheet Nr1374 as well.

The schematics are very good and are almost exactly what I have on my chassis - makes things much easier to locate.

C65 is easy to spot thanks and you will notice that the supporting strap shows signs of leakage - don't know if that's from the capacitors themselves or just the black pitch like coating as C59 and C60 are underneath? Anyway, I think I'll replace all these as access is fairly straightforward and modern equivalents shouldn't be that expensive?

Meantime it's the paint brush and Dyson for me tonight - small steps!
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Old 3rd Sep 2015, 1:24 pm   #32
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Default Re: Philips B3G63A

HI Donald,
Nick is giving (as always) very sound advice there. Working on a dirty or fluff-covered chassis is not the most encouraging scenario, and also whilst cleaning off the grime, you may spot other things that need attention that would have otherwise perhaps been missed.
I used a smidge of trombone oil (a very thin oil) on the push-button assembly - not on the contacts though, to remove some traces of rust on the mechanism. Its a thin, 'creeping' oil, and gives a thin film over the area to which it is applied. Servisol 10 is my choice of contact cleaner/lubricant, but everyone has their particular favourite. Tony.
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Old 4th Sep 2015, 12:19 pm   #33
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Default Re: Philips B3G63A

Well the 1" paint brush and Dyson worked a treat and the worst of the dust and other "stuff" has been removed. Need to get in about it with some cotton buds and probably isopropyl alcohol?

Once that's done I'll look at removing the valves to give them a closer inspection and so some testing (I'll be back for more advice on this).

This has helped to better expose the black pitch type capacitors and a couple of others that may need replacing - see attached image.

Had a look at C65 (the large pinky one at the top of my photo) which is easy to replace and tested R33 which should be 150 Ohms but is giving me a reading of 143-145 Ohms.

In total I've spotted six of these capacitors (numbers and values from Trader Sheet 1374): -

C51 (5μF)
C55 (1,500pF)
C57 (0.1μF)
C59 (0.015μF)
C60 (0.015μF)
C65 (100μF)

(Have I missed something as I thought 1,500pF =0.015μF so C55 = C59 & C60)

There is also C66 (0.001μF) which is connected across output transformer T1 - bottom left of my picture.

So the question is what should I replace these with i.e. capacitor type and voltage (630V ??), and is C66 a special case as I read in an older Thread that someone had replaced this with a 1.6kv ceramic disc cap??

Is there a UK supplier of capacitor kits similar to the ones on sale at http://www.justradios.com/capkits.html
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Last edited by DonaldStott; 4th Sep 2015 at 12:25 pm. Reason: Missed out some info
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Old 4th Sep 2015, 1:37 pm   #34
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Default Re: Philips B3G63A

You can replace the caps with any modern plastic film caps with suitable values and ratings. The voltage ratings should be the same or higher than the originals. If no rating is printed on the cap then 400V or 630V will be fine apart from for the tone correction cap across the output transformer, and it sounds as if this has already been changed.

Modern standard values have changed, so (for example) 0.05uF should be replaced with 0.047uF.

The resistors will normally be fine if within 20% of the design value.

White spirit or WD40 is good for cleaning off dirty waxy deposits, but don't just spray WD40 everywhere - dampen a rag with it. That chassis is actually looking quite clean now anyway.
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Old 4th Sep 2015, 1:59 pm   #35
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Default Re: Philips B3G63A

Thanks Paul - I'm assuming something like these would be o.k.

http://www.ebay.co.uk/itm/10x-Capaci...item2c7378009f

Sorry I misled you on the " ...tone correction cap across the output transformer" as it hasn't been replaced. What's your advice on this one?
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Old 4th Sep 2015, 2:09 pm   #36
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Default Re: Philips B3G63A

Nice to see a good clean chassis to work on. Mine is not so pristine, as I have only cleaned it with the brush and vac.
The capacitor values: 1000pf = .001 uf. 1pf =.000001 uf. So 1500pf = .0015uf, and 15000pf = .015 uf. 1000pf = 1nf, so 10nf = 10,000pf or .01uf
I would not buy any capacitor 'kits' as they tend to be overpriced, and I doubt that you would get one specifically for that model. Some suitable ones here : http://www.cricklewoodelectronics.co...able-for-Audio It says for audio, but they are ok for radio frequencies as well.The 630 volt range will cover all eventualities as regards voltage, and the firm is reliable for good prices and service. I have no connection with them, by the way, just a very satisfied customer over many years.
C66 is unlikely to be faulty. Oh - and C51 (5uf) may need replacing to get the best out of the VHF section.
Disaster has struck! last night. The dial drive for the VHF section on mine has been bodged by some previous repairer, and the drive cord has just thrown in the towel, so I've got that to do as well now!.Grrrrr! Cheers, tony.
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Old 4th Sep 2015, 2:19 pm   #37
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Default Re: Philips B3G63A

Hi Tony and thanks for the Cricklewood link - they look perfect.

As for C66 my instinct would have been to replace it as it's an easy job - but what with?

Sorry to hear about your VHF dial drive - thankfully mine still looks o.k.
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Old 4th Sep 2015, 3:11 pm   #38
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Default Re: Philips B3G63A

The tone correction cap is usually a 1kV component as very high voltages can occur across the transformer primary. That's why I assumed your 1.6kV ceramic cap was a replacement for it. I don't have a circuit to hand so can't refer to part numbers. Can somebody clarify what C66 is doing?

I'm not a historical purist when changing caps and just buy generic types from CPC or Farnell. They are very small and unobtrusive, normally being coloured grey or white. Many people do like to use axial caps that look more like the originals though. Functionally they're exactly the same.

As a general rule, ceramic caps are unlikely to fail.

If you change the 5uF discriminator electrolytic, take care to wire it correctly. The +ve connection goes to the chassis, which is the opposite of what you'd expect.
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Old 4th Sep 2015, 3:24 pm   #39
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Default Re: Philips B3G63A

Quote:
Originally Posted by paulsherwin View Post
The tone correction cap is usually a 1kV component as very high voltages can occur across the transformer primary. That's why I assumed your 1.6kV ceramic cap was a replacement for it. I don't have a circuit to hand so can't refer to part numbers. Can somebody clarify what C66 is doing?

As a general rule, ceramic caps are unlikely to fail.
Apologies again for my badly worded post - C66 has not been replaced by a 1.6kV ceramic cap.

The original cap can still be seen in the bottom left of my previous picture.

I've attached an image for that part of the circuit - hope this helps?
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Old 4th Sep 2015, 3:31 pm   #40
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Default Re: Philips B3G63A

C66 is the tone correction cap as far as I can make out - you definitely don't want a shorted cap in that position as it's likely to take out the output transformer. The design is a bit odd but that's par for the course with Philips.
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