Hi everybody,

There's already been much discussion on this forum about the Zenith Chassis 5516 and its documented and "undocumented" variations. So, I won't try to replicate all that good stuff.

As a quick recap (pardon the pun) for those who don't want to chase down old threads — The 1937 Zenith Chassis 5516 was used in the following radios: the 5S119, 5S126, 5S127, 5S150, 5S151, and the 5S160.

There's a well-documented schematic for the Chassis 5516. You can find it in Riders Volume 7-7.
However, there are many documented owners with Chassis 5516 radios that have different components than specified in the "well-documented" schematic.
One marked difference is the speaker model and field rating. It's 2125 Ohms in the documented Chassis 5516 schematic, but there are many examples of a 1000 Ohm speaker variation.

I'm working on the restoration of a 5S127 with the Chassis 5516 Variant (1000 Ohm speaker - Part 49-165-X). It's not an export model (5A127) but shares a few capacitor and resistor values in common with that export-only version.

Fortunately, my radio has not seen many alterations (or light of day) since it left the factory.
The chassis underside is pretty much unaltered since 1937, I suspect.



I also found that the inside of the chassis and the underside of the cabinet still retain their original factory paper tags.
Here's the cabinet underside tag:



See the Chassis number typed on the tag? It's Chassis 5516B

Here's a closer look:


So, if anyone was looking for factory documented confirmation of the Chassis 5516B Variant — this may be it.

And, if you want to see the differences between Chassis 5516, 5516B, and the Export version, I made a Google Spreadsheet to help identify each component.
I'll be taking readings from my Chassis 5516B to place there.

https://docs.google.com/spreadsheets/d/ ... sp=sharing

Hopefully, this will help anyone trying to restore their Chassis 5516B variants, as following the existing schematic doesn't go well.

Thanks!

Where does the serial number fit in the blocks of numbers assigned to 5516? Wondering if a production run was all 5516B.

Zenith was known to create their own Frankenradios, such as the 40A cabinet with a later chassis installed, the "Stars and Stripes" models, and the 1940 5719 chassis modification with an extra tube, making it into a 5810. The motto must have been "Get them out!"

Martin has found many errors in Zenith's own serial number list.

The serial number for this radio is N 494564. The given range for 5-S-127 radios using Chassis 5516 is between N 489376 and N 501575.

I’d love to see Martin Blankenship’s data on this chassis, but I haven’t found a recent link to the spreadsheet that works.

I think this was a considered and intentional variant, as opposed to a “frankenradio� That term seems more appropriate for non-factory chassis modifications to me.

But, yes, “get them out� would certainly apply!

I've yet to see this one.

I am aware of a 40A cabinet with a 1933 chassis installed.
Pictured in David and Betty Johnson's book "Guide to Old Radios".

For serial numbers, you can either use The Zenith Oracle online or use the green book by Cones, Bryant and Blankinship.
https://www.amazon.com/Zenith-Radio-193 ... 8837&psc=1

-Steve

I used the Zenith Serial Number to Model finder at this link:
https://www.grillecloth.com/zenith/zenith.php

But please let me clarify this isn't a "one-off" chassis/cabinet "mash-up" — but a series of many examples of this undocumented factory-built chassis variation. Half of the Chassis 5516 related posts on this Forum go into this issue again and again.

Part of the reason for calling out this difference is that attempting to recap or restore a Chassis 5516B using the only documented Chassis 5516 schematic creates a whole host of problems. @bastardbus has created an excellent post that helps define the differences between the chassis' here:
https://antiqueradios.com/forums/viewtopic.php?f=6&t=390352

Oh, and to follow up on @AuroraOldRadios question. The serial number on my chassis falls close to the middle of the serial number range specified for the 5516 serial numbers. N 494564 is the 5,188th chassis in sequence after the start of the serial numbers at N 489376. Total production seems to be 12,199 (the range between N 489376 and N 501575.

So, I wouldn't be surprised if there was a production run change after the first 5,000 units.

The Zenith Oracle is very much the same as Grillecloth.com

http://www.oldradios.com/reference/zenith.htm

-Steve

It would be nice to know the serial numbers of the other "B" versions to see if they are all the same production run. If they are, it could point to a parts availability issue.

Parts availability could have been the reason, certainly. I think it's also quite likely that a simplification of the chassis production (Export and Domestic models sharing more common components) may have contributed as well. I wonder if the sales department records or the assembly line efficiency notes from the factory would shed any light on that decision?

Someone on this forum has a 5S127 with a serial number in the N 605100 range — well past the "official" range of the Chassis 5516 as stated in a few archives. "Zenith Oracle" shows it to be a Chassis 5516R. It shares all of the same components of my earlier chassis (R5 at 490K instead of 990K, C16 and C19 capacitor placements swapped, 1000 Ohm speaker FC instead of the 2125 Ohm, etc.)

I suspect the "R" mentioned in the data on the "Zenith Oracle" may actually be a "B" — It's very hard to spot the difference at a casual glance on the tag, but 30 years of graphic design work (and collecting vintage typewriters) give me confidence it's a "B."

I am working on a 2150 ohm version right now. When it is done (about 10 days) I will publish a comparison with the 100 ohm version which is already finished. The one I'm working on now gets the replated chassis in my blog post. Though not particularly relevant, I will also compare the battery (F) model.

Russ

OK, I am almost done with display examples of each of the versions.

I have discovered how to easily ID in most cases.

THE 2150 OHM (fc) VERSION HAS A DIFFERENT BAND SW. It is about 30 deg CC from the other so the "A,B,C" does not line up. It points to BLANK,A,B - no C.

So these can be IDed by the pointer knob - in All examples that I have.

Russ


P.S. In 2 versions of the wooden knob, one has a cast center which sets into the wood with little ridges on the perimeter. If the cast part is pulled out and rotated 1 division of these ridges it will be right-on for the other band sw. The version with JUST a spring steel clip can be rotated too. You must have good aim to get it right.

Also, the 49-AB-143 speaker I have is not 2125 ohms but 2150 ohms.

How many people have one of these chassis with the 49-143 (2150 ohm) speaker - with the large PT or with the smaller one?

I think that I have this figured out, and it was not as I expected.

I have 1 of the 49-143 type chassis and sold one for which I have pictures.

I will be posting a blog entry on these in a day or so.

Russ

I was hoping to hear from other owners of the more unusual version to corroborate my observations - so still looking for input.

I found my 5-S-119 has the 2150 ohm speaker in it. I couldn't get a good look inside as its in an inaccessible spot at the moment.

-Steve

Steve, thanks for the response. I suppose that most people don't know which one they have.

Since you can't get to it, you probably can't answer questions about it's performance. But, in short, I expect it to work, have adequate, but, limited audio quality becoming distorted in the last 1/3 of the pot's range. Do remember anything about it?

I realize from looking at pictures that I sold one of these to a local fellow. He was "old" at the time (now I could say - we were both old) and he was getting it to help him sleep with tinnitus. I thought it was a great cause but that is about all I remember.

Like I said, I have gone through a lot of radios and pictures lately. Another thing to note is a similar problem with the 5-S-151 console. The speaker listed on the schematic is also wrong for it - same problem, but it helps eliminate some reasons that Zenith might have done this. Which leads me to but one conclusion . . .

B.T.W. have you looked at the antenna portion of the 1937 Zenith band switch. It looks like, to me, that it is drawn backwards. The displayed position is impossible, but that is another story.

Russ

'Tis done:

https://www.russoldradios.com/blog/zeni ... 16-chassis

Input welcome particularly those with radios having the 2125 ohm F.C. version.

Notes to take:
Field coil impedance
Power trans
Painted or plated chassis
If you know the values of R5 and R10 as found and as you have them.

I have heard from other 5-S-127, 5-S-126 and 5-S-119 owners but no other console owners.

If there are any spelling errors, I'll fiend them in the morning.

Que Pasa my fellow Z-heads:

I came across this thread and the parallel referenced thread regarding variations of the 5516 chassis. I have been working on a console that uses this chassis. It is marked inside as a 5516P (as in Papa).

I was noticing some potential wiring and component discrepancies between the Rider and Beitman schematics, which are identical, so they seem to have come directly from Zenith at some point.

Anyway, I am not seeing exactly the same issues as detailed in this thread. I have the 1000 ohm speaker, but I'm seeing a difference in one of the coils. I've got what appears to be a different antenna coil assy. Item 3 on the schematic, also related to the band switch wiring being discussed here.

My coil is marked 4725, schematic indicates a 4362. I have them numbered in the pictures as they are shown on schematic.

I tend to agree that some or all of these changes seem to be around the inevitable running design changes, especially during the Zenith of Zenith's popularity. Also that the band switch complicated the schematic and circuitry somewhat. Along with what seems to be different speaker configs that could also be related to the fact that this chassis is used across multiple table models, and a few low tube count consoles, which is somewhat unusual. Maybe cost motivated as well.

Anyway, I looked over the discussion and the different BOMs posted, but wanted to know if anyone has a marked up or updated schematic related to this different 4725 coil. Or LMK if I can contribute anything too the solving of these 5516 chassis variant mysteries. The console is a 5-s-161.

Thanks!
Dave (DCA)

I see that the OP of this thread (Michael - mbhdesign) posted a pic of his chassis, and it's also showing the different coil P/N.

Michael - which schematic / BOM did you use, and does it work?

Thanks,
Dave (DCA)

I have posted the last (I hope) update to the schematic/parts changes on the 5516 chassis.

At the bottom of "Zenith Got it Wrong" is the last entry:

https://www.russoldradios.com/blog/zeni ... 16-chassis

Also don't miss "Zenith Got it Wrong Part Deux" (Duh)

Russ