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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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20th Feb 2018, 5:24 pm | #21 |
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Re: Mullard MAS1764
To expand on what Bill said in post 2 and what dazzlevision has just said. The audio amplifier in the Philips 643A is quite a lot more complicated than your average set. Instead of "that" capacitor" (one component) there are no less than 4 capacitors (C59, C60, C62 and C63) that could cause damage if leaky.
See snip below. The munufacturer's manual is available here. https://www.service-data.com/section.php/5896/1/643a |
1st Mar 2018, 1:21 am | #22 |
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Re: Mullard MAS1764
Belatedly many thanks for that - I was struggling. I have the "Trader" Service sheet 1208. https://www.************************...ILIPS/543A.PDF
and I will certainly get those you list. I fear I am still a little confused. Are those Cap numbers (59, 60, 62 & 63) on your 'snip' taken from the manufacturers circuit diagram - unless I'm being particularly obtuse (a distinct possibility) they don't seem to tally with my 'Trader' service sheet numbers where C59, for example, is only one of a set of four Neg feed-back tone correctors (1500pF). |
1st Mar 2018, 1:32 am | #23 | |
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Re: Mullard MAS1764
Quote:
The manufacturer's data is available here: https://www.service-data.com/product...05/5896/m14605 |
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1st Mar 2018, 3:10 am | #24 |
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Re: Mullard MAS1764
Trader sheets rarely agree with the component numbers on other sheets as they reverse engineered their own off an actual set.
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2nd Mar 2018, 6:29 pm | #25 |
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Re: Mullard MAS1764
I might be missing something, but the R34/35 network on the shown circuit seems rather odd. Is it the same on the other diagrams? Tony.
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2nd Mar 2018, 7:36 pm | #26 |
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Join Date: Apr 2011
Location: Cornwall, UK.
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Re: Mullard MAS1764
So far as I can make out it's drawn correctly, either side of center is treble cut by equal amounts but only on side of center gives treble cut and bass boost, the bass boost switches are ganged to the tone control. There's a brief description in the Trader for the 543a which shows a similar circuit although there appears to be a discrepancy with S25, S26 in the description....So far as I can make out.
Lawrence. |