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Old 19th Feb 2018, 1:54 pm   #1
petergamston
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Default Mullard MAS1764

Complete Newbe to vintage radio I have just acquired a Mullard MAS1764 and can find nothing about it on the Web. Does anyone know anything about these. I know it's a badge engineered Phillips but which model? It looks a lot like a B3G63A, the tuning dial and knobs appear identical but with 6 white keys rather than 5 and a magic-eye where the Phillips badge is on the B3G63A.

The chassis is wider and more complex with 8 valves (all Mullards some appear original, others look newer). (I can't see any way to upload pictures). Everything is currently covered in a thick layer of dust but none of the caps show any obvious signs of leaking. Planning initially just to clean it up best I can without removing it from the case and try powering her up - in the workshop with fire blanket to hand! Anything I really must check first - toolkit currently comprises a cheap multimeter and soldering iron!
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Old 19th Feb 2018, 2:55 pm   #2
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Default Re: Mullard MAS1764

Hi Peter, and welcome.
Use the search box above to look for "that capacitor", a forum nickname for the output grid coupling capacitor. All will become clear.
To post images, have a look at this sticky post: https://www.vintage-radio.net/forum/...ad.php?t=77650
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Old 19th Feb 2018, 2:56 pm   #3
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Default Re: Mullard MAS1764

Read the stickies on the top of the vintage radio domestic section, where you posted.

Upload photos with the attachment paperclip on this message header.

There are instruction threads, please use 'search' and read them.

What are your skill levels with electronics please? Are you used to working on mains connected equipment?

The output valve grid 1 coupling capacitor will need to be changed as an absolute minimum to prevent destruction of output valve, output and mains transformers.

You need to do some meter checks before you plug it in.

Build yourself a lamp limiter and use it on initial connection to the mains.

Read as many restoration threads as possible, you will learn masses of sound instruction and achieve a good outcome.

Ask questions, we will help you provided that you show an understanding of what is involved.

Sam.
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Old 19th Feb 2018, 3:29 pm   #4
ms660
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Default Re: Mullard MAS1764

Wonder if it looks anything like this?:

https://www.radiomuseum.org/r/philips_b5x72a.html

Lawrence.
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Old 19th Feb 2018, 3:39 pm   #5
Boater Sam
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Default Re: Mullard MAS1764

Pretty if it is. Wonder what the EF86 is for, must have a butchers at the circuit.

There is no EF86 on the diagram!

Last edited by Boater Sam; 19th Feb 2018 at 3:46 pm. Reason: Added
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Old 19th Feb 2018, 3:47 pm   #6
petergamston
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Default Re: Mullard MAS1764

Hi Lawrence. Not exactly.
(when I said 8 valve that includes the EM80 indicator which I guess you knowledgeable don't count.)
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Old 19th Feb 2018, 3:54 pm   #7
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Default Re: Mullard MAS1764

No EF86 in the Mullard
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Old 19th Feb 2018, 3:55 pm   #8
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Default Re: Mullard MAS1764

No EF86, but there is an EL86 in what looks like a high speaker impedance transformerless output stage.

Lawrence.

Last edited by ms660; 19th Feb 2018 at 4:04 pm. Reason: correction
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Old 19th Feb 2018, 4:01 pm   #9
Boater Sam
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Default Re: Mullard MAS1764

Got it, terrible small printing, so its EL86 unusually with EL84 in a non push pull output. Is one a current driver for the other? Philips did like complications.
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Old 19th Feb 2018, 11:35 pm   #10
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Default Re: Mullard MAS1764

The Mullard set looks like it shares the same case as the UK Philips 543A which has the same valve line up apart from the magic eye and there is a Philips Finland set, the BSF543A, which looks to also have the magic eye (wood case) - don't know if the service info for these would be any help?
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Old 20th Feb 2018, 12:50 am   #11
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Default Re: Mullard MAS1764

The EL86 is used in a single ended transformer-less push-pull output with the EL84. The Spec sheet for EL86 shows this use.
Its not a configuration I have seen before, or a valve I have seen either.

We have been here before. https://www.vintage-radio.net/forum/...d.php?t=103136


Is this the set in the thread or are we off on a tangent again?

Last edited by Boater Sam; 20th Feb 2018 at 1:09 am. Reason: Added
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Old 20th Feb 2018, 12:55 am   #12
petergamston
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Default Re: Mullard MAS1764

Looking at the chassis shot of the Philips 543A that's certainly the same as mine.
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Old 20th Feb 2018, 12:56 am   #13
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Default Re: Mullard MAS1764

Thanks Steve - that's it alright. Peter
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Old 20th Feb 2018, 1:03 am   #14
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Default Re: Mullard MAS1764

That is a pretty bonkers design, even by Philips standards.
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Old 20th Feb 2018, 1:12 am   #15
petergamston
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Default Re: Mullard MAS1764

Maybe not my wisest choice for a first attempt then!
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Old 20th Feb 2018, 1:16 am   #16
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Default Re: Mullard MAS1764

Philips radios generally aren't a great choice for a beginner. They are notorious for idiosyncratic design. That doesn't mean you can't sort it out though.
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Old 20th Feb 2018, 1:22 am   #17
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Default Re: Mullard MAS1764

Philips never are! Always complicated, cord drives can be a nightmare.

But it depends what is wrong with it. It has not got the transformer-less output stage that we were discussing, more conventional. If the piano key switches are OK it should be fine.

Several black tar caps which will be leaky.
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Old 20th Feb 2018, 12:12 pm   #18
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Default Re: Mullard MAS1764

Quote:
Originally Posted by petergamston View Post
Looking at the chassis shot of the Philips 543A that's certainly the same as mine.
The Philips 643A is probably a closer match as it also has an EM80 tuning indicator but is otherwise very similar to the 543A.

https://www.radiomuseum.org/r/philips_643a.html
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Old 20th Feb 2018, 1:17 pm   #19
petergamston
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Default Re: Mullard MAS1764

Cosmetics aside that's exactly it. Thanks everyone for your help. I'm away for a few days but will build a light limiter as soon as I'm back home. Seller assured me there is nothing wrong with it and it works fine. I take that with a large pinch of salt but am still inclined to 'give it a go' via the light limiter (and RCD breaker of course)
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Old 20th Feb 2018, 2:06 pm   #20
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Default Re: Mullard MAS1764

I have a Philps 643A and it is a lovely looking set, with an extra IF amp stage (EF85) on VHF, making it more sensitive. The sound quality is very good on VHF/FM.

Apart from replacing the usual black wax coated Philips paper dielectric capacitors, a lot of the resistors are those light green coloured body types (made by Erie?) that don’t seem to drift high and out of spec. I expect your Mullard set will have been made in Croydon, like the Philips 543A and 643A.

I didn’t have any trouble with the piano key switches.
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