all wave 15 choke problem

[norman david warren]

Hello all I have a Scott all wave 15 LATE with a shorted to ground filter choke(The one mounted on the top of the chassis.) the only info on the schematic says it is a 30 Henry choke but no info as to the DC resistance. has anybody had a problem with this part, and if so what did you put in to solve this? Thanks in advance. Norman W

[Kent King]

Norman -

It is unusual for the P/S chokes to short to ground. It probably got hot due to a shorted filter and melted the internal insulation. Fortunately, I have some spares around here. Unfortunately, I am leaving early tomorrow morning for the Kutztown meet and I won't be back until late Saturday. I'll try to look on Sunday and see if I can locate a replacement for you. If your chrome on it is nice, you may want to disassemble it and use your chrome over what I might have...most are pretty rusty - pulled from really rough chassis...

Kent

[David C. Poland]

You asking about the choke mounted on the 3 tube AW-15 amp?

The Scott chokes are pretty sturdy. A 30 Henry choke was used on several Scott amps, so one from a parts set is not hard to find. Advantage is it will have the chrome cover, fit the mounting holes and the have correct rating. But avoid the 10 Henry choke that looks the same from an  AW-23 High Fidelity Allwave and 30 tube Philharmonic model amps which has both type amp chokes.

The fiber board where the two wires exit have the part number:

30 Henry #0221 suffix S or W per documentation - about about 50  ohms per notes I have.   

10 Henry #3077 about 50 ohms (measured one I have)

These numbers may have some suffix letters.

I have a Scott 30 Henry available, with different suffix 0221AB at higher 190 ohms from a later Scott but the chrome is rough. ([e-mail]). Greater resistance  would reduce B+ bit, maybe not bad with the higher 120 plus ac voltage in many areas today.

Be sure to trouble shoot the cause. Excessive current from a short? Or voltage spike if powered up with no load?

*

A Scott amp should never be powered up without the load of 1) the receiver and 2) the correct field coil speaker.

The correct Scott pedestal 12 inch speaker has two field coils and is specific to an AW-15.

*

AND, please mention the Serial number from the receiver for the Scott production project. (format A-NNN)

[norman david warren]

Kent  Thank you for the offer I can reuse my cover  This chassis (no cabinet) was given to me by a horder friend. When I got it I replaced the 3 8 mfd filters on the P/S chassis as well as the 2 8mfd filters in the tuner I dont know what the previous owner did although i know he is not a technision.

 David: Thanks for the tech heads up- I am supsious of the speaker since it started to get hot also. will test tuner chassis for shorts before powering it up. Again thanks to the both of you gents. Norman W

[David C. Poland]

Suggest you show photo of the speaker you have for confirmation. When new, had an E H Scott decal on the back.

I have had to have the B+ field coil re wound on a couple of the AW-15 speakers over th years.

The 3 tube amp should have tube numbers embossed on the tube sockets:  two 2A3 and one 5Z3.

Speaker socket is 6 pin. Set cable has a large 6 pin Jones plug.

[norman david warren]

Thank you David. I will post a picture of the speaker later this afternoon the Scott decal is worn off. Regards  Norman

[norman david warren]

Dave. Here are 3 pictures of the speaker I got with the Allwave 15 Late. Hope this helps. Norman

[David C. Poland]

Yes - is the correct speaker (most commonly seen basket design) and with original output transformer inside.

Refer to the circuit diagram to check resistance and continuity of the field coils and output transformer.

FYI - the speaker is a special design by Jensen.

The AW-15 evolved considerable during the I year of production. We have 5 diagrams, but your example may straddle two diagrams.  

Initially, the 2nd detector was a blue glass Wunderlich (by Arcturus) and the receiver had additional 2 red antenna posts for shortwave. 

Mid production, Scott changed to a 55 tube for 2nd Detector, and the dropped the red SW antenna posts - and the  diagrams in Riders are of the later using the 55 tube. 

But there were numerous other changes. 

Eventually the Wunderlich tube became unavailable, and a number of earlier examples were converted to use the 55 tube.

[norman david warren]

My tuner does NOT have the 2 red antenna termanls. the 55 tube socket looks original no sign of a conversion from the "Wunderlich tube to the 55 tube. thanks for your help Norman W.

[David C. Poland]

OK - then the tube socket has 55 embossed on it. Just the one antenna post and a ground post. Late production Fall 1934 to early spring 1935. the two Riders diagrams should apply

[norman david warren]

Kent: If you have a choke for an allwave 15 power supply chassis how much? I can reuse my cover if nessesary. Thank you  Norman W

Kent King said:

Norman -

It is unusual for the P/S chokes to short to ground. It probably got hot due to a shorted filter and melted the internal insulation. Fortunately, I have some spares around here. Unfortunately, I am leaving early tomorrow morning for the Kutztown meet and I won't be back until late Saturday. I'll try to look on Sunday and see if I can locate a replacement for you. If your chrome on it is nice, you may want to disassemble it and use your chrome over what I might have...most are pretty rusty - pulled from really rough chassis...

Kent