Intro and info.

[Pat Taylor]

Glad to have found this website!

As a retired hobby, I've restored over 100 radios in the last 9 years or so. And I'm finally getting around to my first E.H. Scott, which is an AM/FM Phantom deluxe in a Chippendale Grande cabinet. To see some of my work, check eBay for a Sparton 1268. One of the few I currently have listed.

Info is really all I need now. After checking all the usual schematic sites, including the ones here, and my original Rider's, I can't find an appropriate schematic. This is a 22 tube (including the voltage regulator and 2 eye tubes) chassis, not including the amp. It originally had the 3 speaker system, but the only thing left is the woofer and the crossover.

Also, it's missing 3 tube shields, and 15 out of the 16 shield caps. Other than continuously checkin eBay for these, are there any available elsewhere? 

I'm in the process of stripping the entire cabinet now, and it looks like the chassis will have to be rechromed.

Thanks for listening to me, and I look forward to any replies.

Pat

[Norman S Braithwaite]

Scott, I've never encountered a problem with them. They are the equivalent of the Sprague TM series. How have you found them to be unreliable?

Norman

[Pat Taylor]

Yes. They are all PM. I shall replace them. Thanks.
Scott Seickel said:

Dubilier made green tubular capacitors that are paper/Mylar.   The capacitor would have PM in the number that stands for paper/Mylar.     They might test ok for leakage, but they are unreliable.    If that is what you have, toss them.  

[Pat Taylor]

O.K. Now I'll hold off until... 

[David C. Poland]

Make sure you have the plug inserted in the 4 pin socket. If missing, fashion a jumper as per the diagram in Riders I referenced. No jumper, no sound. This 4 pin socket is for an optional extension speaker.  The 5 pin socket is for the 12 inch speaker which is critical as it includes the B+ circuit to the tapped field coil.

The 12 inch Hi fi Scott  speaker has an 8 ohm voice coil. The Scott speaker diagram in Riders I referenced says tweeters are 16 ohm. There have been some eBay listings for 4 inch closed back Jensen tweeters at 16 ohms for a reasonable $25 or so. The crossover supports two, or just one. 

for example. eBay item number:  325238291182

The Crossover contains a pair of 2.35 MFD caps to replace. My crossover caps were leaking badly and I replaced them with film caps.

[Pat Taylor]

Thanks David. It all helps.

[Scott Seickel]

Norman,

I have a habit of often testing the capacitors I cut out, and I can't say I have found more than a couple of bad PM series C-D's over the years, but I do recall people on ARF who have have stated that they found them to be unreliable.  On the other hand, I don't recall ever finding a Sprague DiFilm capacitor that was bad.  Maybe the C-D's didn't use oil?  Maybe they were early versions of their PM series?  Maybe it was bad luck, but others have complained too.  I don't know, but I would cut them out as long as I was there. 

These capacitors are 60 or more years old and considering that the dielectric is paper which will absorb moisture, it seems reasonable to replace them even though the mylar film will slow any leakage.  If they were just a film capacitor, I would leave them. 

[Norman S Braithwaite]

Scott:

Thanks for your response.  I take the opinions on ARF with a rather large grain of salt.  Some don't like the Sprague TM series also.  When it comes to capacitors I develop my own opinions based on my experiences and well trusted sources (of which you are one).  Based on this information my opinion is that the C-D capacitors are most likely good and dependable but there is a possibility of one or more developing a problem.  I would test high impedance circuit voltages and if within reason would leave them.

Norman

[Alex R. Whitaker]

I've also never had a problem with paper/mylar dipped caps.  I have tested lots of them, and left them on the 600 volt scale (or whatever voltage they're rated at) on my cap tester with no discernible leakage after several minutes.  Of course, anything, including a brand new cap, can become defective.  I've put them in several sets, and, after extensive listening, have never had a problem. 

[Pat Taylor]

Norman, which 2 pins sould be shorted? I can't find that info anywhere. Thanks.

Norman S Braithwaite said:

Tweeters were designed to only work on FM if there is a cord with a small four pin plug that fits a socket on the back of the tuner chassis. Not all sets were so equipped. If your set is equipped with the tweeter cut-out you can override it by shorting two pins on the plug.
Norman

[Scott Seickel]

Attached is my diagram of the network speaker setup.  You can see from the diagram how it operates and which pins short on FM. 

[Pat Taylor]

That's a great diagram! So according to that, pins 2 and 3 need to be tied together, as well as pins 1 and 4? 

Scott Seickel said:

Attached is my diagram of the network speaker setup.  You can see from the diagram how it operates and which pins short on FM. 

[Kent King]

Not at the same time...I used a DPDT switch and a female plug from a parts chassis and created a tweeter on/off switch. I prefer to keep them on most of the time.

Kent