10th Mar 2016, 8:10 pm | #141 |
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Re: Philips B3G63A
Yes quite right. If you look around the set, you'll find other similar ones (there is a smaller one showing in your picture), some green, some beige... maybe even the odd red one. I don't think the colour was significant. Good ceramic caps... never seemed to give any problems.
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11th Mar 2016, 1:54 pm | #142 | |
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Re: Philips B3G63A
Quote:
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11th Mar 2016, 7:21 pm | #143 |
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Re: Philips B3G63A
Yes they are... part of the 'loudness' compensation. Popular with continental sets, it compensates for the non-linearity of the human ear with regard to low frequency notes. As volume is reduced, low frequency notes become less audible so the 'loudness' circuit (a Philips term) increases the bass slightly as volume is reduced. Most sets with a tapped volume control work this way.
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12th Mar 2016, 12:05 pm | #144 |
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Re: Philips B3G63A
Thanks for the excellent explanation Sideband -I'm very familiar with the "non-linearity of the human ear with regard to low frequency notes" due to my experiences with modern high end hi-fi systems. Need to do more background reading on sets of this era.
If I were to shunt "a small value capacitor across C54 fixed, and a similar capacitor across C56" as suggested by Hetrodyne then what values/types would be recommended. The weather is still to cold and damp to tackle any cabinet spray painting this weekend... |
17th Mar 2016, 8:19 pm | #145 |
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Re: Philips B3G63A
Another quick question about the speaker in this set which is bit fragile?
The Trader Sheet shows this as L25 with a value of 3Ω - however I've attached a picture of the actual value stamped on the speaker which clearly shows 5Ω. Anyone have any knowledge of these particular speakers? |
17th Mar 2016, 8:55 pm | #146 |
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Re: Philips B3G63A
The difference isn't significant. 3 ohm speakers were standard during the valve era, but Philips did use some odd values, including 5 ohm.
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18th Mar 2016, 12:18 pm | #147 |
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Re: Philips B3G63A
Thanks again Paul - good old Philips never ceases to keep us amused, even today!
I've possibly sourced a suitable 8 ohm speaker and was wondering if there would be any real issues with that or would I need to consider connecting something like this: - http://uk.rs-online.com/web/p/audio-...rmers/2106475/ |
18th Mar 2016, 12:23 pm | #148 |
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Re: Philips B3G63A
No, 8 ohm will be OK too.
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18th Mar 2016, 12:24 pm | #149 |
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Re: Philips B3G63A
If you have an 8 ohm that fits I would use it, I would not be buying matching transformers.
Frank |
18th Mar 2016, 3:42 pm | #150 |
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Re: Philips B3G63A
Hi Donald,
regarding the above - what output you gain in accuracy of impedance matching, you may lose in transformer losses. All transformers are inefficient, and as Frank says, dont bother, - just fit it!.Tony |
25th May 2016, 1:55 pm | #151 | |
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Re: Philips B3G63A
Quote:
Hetrodyne had recommended "If you want to reduce the treble response you could try shunting a small value capacitor across C54 fixed, and a similar capacitor across C56 to give variable control then fit a suitable single component in their place when a satisfactory audio is found..." but I'm not sure what value or type of capacitors to try? |
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25th May 2016, 5:09 pm | #152 |
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Re: Philips B3G63A
On a (typically Philips) 5 ohm secondary, the 8 ohm LS will be fine. If you do notice anything there will be a slight reduction in output as compared to the previous volume setting i.e. you may just need to turn it up a bit. Edward
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25th May 2016, 5:15 pm | #153 |
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Re: Philips B3G63A
Going over the circuit again, C54 is 33pF part of the volume loudness circuit, and C56 the grid coupling capacitor so should be left alone. To give an overall slight cut in the top end a capacitor of around 0.001uF could be tried across the top end of the tone control R31 to chassis, a low voltage one will be alright, assuming C59 the tone control capacitor is actually working. What was actually wrong with the original speaker.
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25th May 2016, 10:50 pm | #154 |
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Re: Philips B3G63A
Thanks Hetrodyne for the additional information - I'll try and locate R31 and C59 but may get back to you to ensure I'm making the right connections.
The original speaker had seen better days! The paper cone was very fragile and the sound quality was quite brittle. Replaced it with an 8 ohm 6½" diameter Monacor speaker from Wilmslow Audio. What a difference it made to the sound quality. The brittle, over-bright sound from the old speaker has disappeared and we have tons more detail, deeper bass and an overall better response at all volumes. Can't complain though as the old speaker has seen 60 years of service! |
27th May 2016, 11:06 am | #155 |
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Re: Philips B3G63A
Just a quick update as I'd forgotten that C59 was one of the Philips black pitch capacitors and has therefore been replaced with a modern equivalent - so that's working fine.
Trader Service Sheet 1374 clearly shows the location of R31 (the Tone control) and adjusted by the innermost spindle: - It is clear, however, that in my Radio, the innermost spindle is the Volume Control while the outermost spindle is the Tone control - curious?? This labelling is replicated in the underside schematic for the Radio: - Is this just a simple typo on the Trader Sheet, albeit twice, or is there something else going on here?? |
27th May 2016, 11:27 am | #156 |
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Re: Philips B3G63A
Trader sheets did have mistakes in them, it could just be a mistake.
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27th May 2016, 11:35 am | #157 |
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Re: Philips B3G63A
I'm looking at a non Trader manual, volume inner, tone outer, on/off by a switch on the main push switch bank and not combined with the volume control as shown in the Trader sheet.
Lawrence. |
27th May 2016, 11:46 am | #158 | |
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Re: Philips B3G63A
Quote:
Looking at the Tone control part of the circuit diagram, I've replaced C59 and C60 while C61 is a Ceramic Capacitor that should be o.k. Hetrodyne has suggested " ..a capacitor of around 0.001uF could be tried across the top end of the tone control R31 to chassis" - not sure where the connections should be? |
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27th May 2016, 11:51 am | #159 |
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Re: Philips B3G63A
Connect the suggested 0.001uf across C61 on the Trader sheet.
Lawrence. |
27th May 2016, 12:03 pm | #160 |
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Re: Philips B3G63A
Thanks Lawrence for your quick response - will do...
Last question, honest - 0.001uF 100V Mylar Film Capacitor OR 0.001uF 630V Axial Polyester 10% Tolerance Capacitor Last edited by DonaldStott; 27th May 2016 at 12:20 pm. |