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 WANTED - Speaker for AWA 429MA
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 Return to top of page · Post #: 1 · Written at 8:06:44 PM on 10 August 2017.
Bolster's Gravatar
 Location: Lawson, NSW
 Member since 10 August 2017
 Member #: 2149
 Postcount: 2

Anyone have a speaker for an AWA 429MA radio?

Happy to pay a fair price.

Thanks.


 
 Return to top of page · Post #: 2 · Written at 8:48:19 PM on 10 August 2017.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 3972

5 inch circular? What impedance?


 
 Return to top of page · Post #: 3 · Written at 9:53:43 PM on 11 August 2017.
Bolster's Gravatar
 Location: Lawson, NSW
 Member since 10 August 2017
 Member #: 2149
 Postcount: 2

According to the documentation I have, the speaker is 5 inch circular with a VC impedance of 3 ohms . 400Hz.


 
 Return to top of page · Post #: 4 · Written at 3:29:23 PM on 31 August 2017.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 553

Just looking at recapping a 429-MAat the moment. The parts list includes a 9uμF mica, but the schematic does not show it. Have you found it?


 
 Return to top of page · Post #: 5 · Written at 8:55:31 PM on 31 August 2017.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 3972

The parts list includes a 9uμF mica

Not shown in my list. What 'C#' is it shown as?


 
 Return to top of page · Post #: 6 · Written at 9:07:02 PM on 31 August 2017.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 553

It is C23, as shown in document on Kevin Chants site.


 
 Return to top of page · Post #: 7 · Written at 9:38:03 PM on 31 August 2017.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 3972

My AORSM list, on p52 of I don't know what volume but possibly Vol 9, stops at C22 (0.05 paper, 400V)


 
 Return to top of page · Post #: 8 · Written at 7:52:25 AM on 1 September 2017.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 553

OK, thanks for that, I'll forget that cap.


 
 Return to top of page · Post #: 9 · Written at 9:45:54 AM on 1 September 2017.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 2730

If its Mica I would not bother with it. Draw where it is if there is one you cannot identify; Some caps are on coil sets as part of the coil set & are not marked. If I have one out of circuit I test it.

I have a copy of one AWA set where it has parts for two sets listed and one of them was not a production model & I had to draw its circuit.

I would have a look at the circuit on Kevin Chant's site & see where it is: It may be an in production factory Mod as they changed something?


 
 Return to top of page · Post #: 10 · Written at 5:33:27 PM on 1 September 2017.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 553

OK I'll keep a look out for it. I agree it might be around a coil because of its 9uμF value - I think otherwise they would have just used a common or garden garden 1uF.

The circuit on Kevin's site doesn't show it even though it is on the parts list.

Correction: 1μF should be 10uuF.


 
 Return to top of page · Post #: 11 · Written at 8:15:08 AM on 2 September 2017.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 553

There is also a photo of the underside of the 429MA with all parts labelled: there is no C23.

Kevin's circuit for the 430MA does have a 9uμF cap (C11) and it is located parallel to the oscillator coil L7 and its trimmer C10. So that's probably the place to look on my 429MA.

The underside of the 429MA is beautifully preserved, as is the rest of it except for the knobs (replaced thanks to Steve) and a few minor cracks on the top at the cabinet join. A pity to take out these caps but I am not going to embed new components for this love job.


 
 Return to top of page · Post #: 12 · Written at 10:04:00 AM on 2 September 2017.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 2730

One must never forget that the "Coil set"; Consisting of the Gang/s & coils are a totally separate entity. An Astor radio & others had Stromberg -Carson Gangs. The power transformers, were commonly not made by The radio maker.

Many techniques were used to correct the band spread & tracking in general, so that unmarked cap on a coil set, should never be touched without good reason. Because the coil set is just that: Problems can arise if you change any part it. If you change 6A8 to 6J8 in an Astor JJ (one example) the 6J8 causes the band to be compressed & the lower end to move well into the Long wave Aircraft NDB's.

9pF is common in many AWA sets, in the loop that forms the oscillator.

There are two considerations with radio repairs, which also apply to old radio's: Do you want it to work or don't you. If you are going to make it work it may as well be done so it works properly: If that involves tossing every cap, so be it.

I had a nice (have photo's) untouched "Roberts R66" go through. The owner wanted it working: Simple tested everything, noted one chassis mount ecap leaking cut it & its mates out of circuit & replaced 5 caps (only had one paper) & re-calibrated it as it was out: No cap replacement: No go. I didn't even power it: Leaking cap says not on.

On that: I just had to ask as to how it was determined in the article in the Vintage Radio section of SC August that the paper caps were good? In over 50 years I have rarely found a good one. The fact that it tests say 0.05mfd and has that on its label is no indication of it being good.

Those of us that have fixed for decades know that old capacitors leak. The only way to test a Non polarised cap like a "Waxed Paper" or Mica, is to apply a DC voltage as close to its working voltage, or that which it will be working at (preferably the higher) using an insulation tester (or similar... Altronics have the ideal one for HV).

If it tests 50Meg or less, it is not suitable for screen decoupling; below 200Meg usless for coupling plate to grid as is will send the grid positive to some extent. I have never seen a common wax paper cap that good. That does not apply to the ones like Type 5S10A in a sealed can (but test them).

As modern caps don't leak, any cap that does leak (99.99% of the wax paper ones in the radio's we have) is tossed.The wax paper in the Roberts (AGC) tested 0.7Meg: Instant replacement.


 
 Return to top of page · Post #: 13 · Written at 4:01:31 PM on 2 September 2017.
Fred Lever's Gravatar
 Location: Toongabbie, NSW
 Member since 19 November 2015
 Member #: 1828
 Postcount: 195

Hey guys just a note on 'mystery caps' especially tiny PF values and you cannot find, on one set diagram there was the note " capacitor is part of wavechange switch mechanism". I think it was a neutralising cap and when you looked at the physical wires running parallel to each other and the proximity of the wafer contacts....you sods!!! Right in front of my nose and invisible. Also I have seen on a coil set the famous short wire pair cut to length, yep that's a cap...sods!!! Have used the twisted pair myself when I wanted a couple of pf, or, used a bit of shielded cable. And then there are the STC or is it Philips sets with the little ceramic tubes with wire turns trimmed to pf size.......great when you want to adjust them!
Cheers, Fred.


 
 Return to top of page · Post #: 14 · Written at 5:10:08 PM on 2 September 2017.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 3972

Kevin's circuit for the 430MA does have a 9uμF cap (C11) and it is located parallel to the oscillator coil L7 and its trimmer C10

My documentation shows C11 as 0.05μF paper 200V, and the oscillator coil is L4 with its trimmer C7, and L7 & L8 comprise the 2nd IFT. so yours sounds to be quite a different version of the 429MA.


 
 Return to top of page · Post #: 15 · Written at 8:33:52 PM on 2 September 2017.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 553

"My documentation shows C11 as 0.05μF paper 200V"

I might have confused you by referring to 9uμF cap in 430-MA. Only did that to indicate what use AWA made of this cap in their 4 valve radios of the day, and likely site for it in the 429-MA if indeed it is there.

"Do you want it to work or don't you. "

I do want it to work and understand fully the fact that the electrolyics and paper caps must have something done about them. If it was my radio I would stuff these if possible to retain the look of the parts because they are in pristine visual condition. But it is a love job and there can be no compromise on reliability. Paper caps that are OK for their job now might deteriorate in the future.


 
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