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 Post subject: What a difference 125,412 can make
PostPosted: Nov Mon 05, 2018 3:43 am 
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I acquired another $20 ZTO G500 this weekend. This one is the lower unit in the photo, with the green selenium rectifier, the number stamped into the metal on the chassis back is 186502.
The top unit with the orange rec is another G500 I bought this spring and has 061090 stamped in the metal on the chassis back.
Were there 125,412 units built between these two? (That seems like quite a lot!)
After studying the new one for one evening, seems the layout in the top one is messy compared to the lower one and the components are different, the black resistors in the bottom unit and brown capacitors for example. Wiring layout seems to be very close. Colors on the wire fabric and general condition seems much better on the lower unit.
Was the top one was built by someone having a bad day? The soldering style is very different between the two as well, the bottom one seems to have used much less solder and component placement is neater, more orthogonal, you could actually get a probe on the pins of the 3V4 without pushing too much. Thinking of the difference between FOXCON made electronics today and the Zenith manufacturing process then is, well, daunting.
A search of the forum didn't give up a ZTO G500 serial number series, so I'm not sure if the number I'm referencing is the correct one, see red box in bottom picture.
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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Mon 05, 2018 1:32 pm 
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sergneri wrote:
Was the top one was built by someone having a bad day?

Both radios were built on a assembly line, numerous persons had a hand in assembly. With less experience on the model,
no doubt workers were not as neat in early production units(look about same to me).

Code dates on components will give a approximation of period radios were built. I believe for TO that info has been well researched.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Mon 05, 2018 4:50 pm 
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The biggest difference I see is the 1 or 2 watt 820K resistors on the socket next to the rectifier, 3V4 ?, were replaced with smaller 1M resistors. Yes, that makes more room at the socket.
Anyway, it is interesting to compare.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Mon 05, 2018 6:59 pm 
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Zenith will have stamped the speakers with a date code.

343 equals Zenith...
viewtopic.php?p=751406#p751406


Example: 343818
343 - Zenith
8 - 1948
18 -18th week

Greg.


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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Mon 05, 2018 8:29 pm 
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Did a little sleuthing, this link states around 90,000 G500 were built.
I thought there was unlimitless info on these but I didn't find much either.

http://www.radio-antiks.com/IndexRadio- ... h_G500.htm

I will take a stab that 061090 is the 61,090 built, year 1950 &
186502 was 86,502 built, year 1951.

That'd place builds 25,412 apart

If the one with higher ser number was built in 1951, I'd bet my guesstimation is correct.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Tue 06, 2018 12:12 am 
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35Z5 wrote:
Did a little sleuthing, this link states around 90,000 G500 were built.
I thought there was unlimitless info on these but I didn't find much either.

http://www.radio-antiks.com/IndexRadio- ... h_G500.htm

I will take a stab that 061090 is the 61,090 built, year 1950 &
186502 was 86,502 built, year 1951.

That'd place builds 25,412 apart

If the one with higher ser number was built in 1951, I'd bet my guesstimation is correct.


Well that makes much more sense, with the 0/1 year indicator. Love to know if a 49 series started with a 9. That makes me and the 186 born in the same year. My sleuthing showed some hits for H500 and H600 serial numbers, but not so much for G500.
90K units is still a lot of radios, but alas, not "unlimitless". :D

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Tue 06, 2018 1:16 am 
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The one featured in link I posted has ser of 074983, speaker and electrolytic cap both have mid '50 code dates.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Tue 06, 2018 6:48 pm 
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sergneri,
I, with the help of respondents and photos I have found on the internet, have compiled serial production data on the G500 (plus hundreds of other Zenith models, 1923-1960). I plan to post a summary of this compilation on the G500 this evening.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Wed 07, 2018 2:32 am 
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Martin Blankinship wrote:
sergneri,
I, with the help of respondents and photos I have found on the internet, have compiled serial production data on the G500 (plus hundreds of other Zenith models, 1923-1960). I plan to post a summary of this compilation on the G500 this evening.

Let me know if either of my G500's can help - I can hear them volunteering from here.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Wed 07, 2018 4:26 am 
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sergneri,
I will need to check my data before posting--maybe tomorrow evening. I have serial information on 199 units.

It looks like you posted photos on one of your radios. If you can find the RETMA codes on the tuning condensers, which usually has an R/C (Radio Condenser Co.) 273 (mfr code) followed by six digits. The first three of those six would be the year and week. Example 273-008-108 would be a Radio Condenser Co. tuner manufactured in the eighth week of 1950. I don't know what the last three digits denote.

Thanks,

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Wed 07, 2018 4:54 am 
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Martin,
Unit 061090 is 004 (January 1950)
Unit 186502 is 037 (September 1950)
Edit: Last three digits on both is 108.
Cheers,
John

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Wed 07, 2018 6:52 am 
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In the hopes of contributing to the investigation here, I pulled down by G500 and recorded the serial number and a number of production codes.

Serial #: J-198363
Speaker Date Code: 343939 (Sept.-Oct. 1949)
Tuning Capacitor Date Code: 273-937-108 (Sept. 1949)
Electrolytic Can Date Code: 102948 (Nov.-Dec. 1949)

I also took a look at my copy of Bryant & Cones The Zenith Trans-Oceanic: The Royalty of Radios. They list that total production for the G500 was 89,681 units with 16,244 being produced in 1949, 51,634 being produced in 1950 and 21,803 being produced in 1951. They also say that the G500 was last offered in print advertising in May of 1951.

With the data listed in this thread we can summarize the following:

Unit J-198363 would have had to have been made after Dec. 1949
Unit 061090 would have had to have been made after Jan. 1950
Unit 074983 would have had to have been made after June 1950
Unit 186502 would have had to have been made after Sep. 1950

It would not appear that the serial numbers follow a congruent pattern as the OP points out there are 125,412 proposed units between his examples and with less than 90,000 examples produced (and only 51,634 in 1950) there can not be examples bearing every serial number.

I hate to correct 35Z5, but with only 67,878 examples produced in total by the end of 1950, that eliminates the possibility of the first digit representing the year as Unit 074983 could not have been the 74,983 example produced in 1950. Unless of course there were non-continuous serial number blocks being used.

My example also throws a wrench into the mix, as it has a J-Prefix, as do a number of other examples I have seen, which have the serial number printed on a paper tag affixed to the chassis rather than being stamped on.

I too would be interested in hearing the findings of Mr. Blankinship and whether he has a solution to decoding the G500 serial numbers.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Wed 07, 2018 4:32 pm 
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Hcompton79 wrote:
I hate to correct 35Z5, but with only 67,878 examples produced in total by the end of 1950, that eliminates the possibility of the first digit representing the year as Unit 074983 could not have been the 74,983 example produced in 1950. Unless of course there were non-continuous serial number blocks being used.

LOL, I was already 99% sure my suggestion was wrong. Found a H model that ser number started with 2, speaker date code was in '53.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Wed 07, 2018 4:40 pm 
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Has anybody given thought to the possibility that the serial numbers are consecutive for ALL Zenith radio production in a given model year, but are not necessarily consecutive for any given model? In other words, if you had 4 assembly lines and 20 radio models, you might run assembly line "A" building one model for a week, then run a totally different model the next week on the same line. That would run through a lot of serial numbers in a hurry but there would also be gaps in the sequences within any given model number.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Wed 07, 2018 4:57 pm 
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I plan to pull data from three G500's I have on hand to compare information. I have two chassis' that appear to have numeric serials only and one that has the "J" prefix. On my examples. the numeric serials are stamped into the chassis and the "J" serial is on a paper label. If you look at earlier serial number issues on other radios from Zenith, you will note breaks in number series that were applied to other models. That would probably indicate serials were issued consecutively and when one chassis production ceased, another took up the next series and when production is resumed, the next number series was started leaving an apparent gap. It's too bad that the serial tag was just an applied paper label that would readily fall off. Does someone have a chassis with a stamped serial that matches a paper label?

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Wed 07, 2018 5:13 pm 
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Bugman wrote:
Does someone have a chassis with a stamped serial that matches a paper label?

In banging around on net I did locate one that had sticker and stamp(unfortunately I don't remember where). Sticker began with letter that wasn't on chassis but numeric digits did match.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Wed 07, 2018 5:21 pm 
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Thank you, Tom. I wonder if the "J" was the regular prefix for the G500? I will be looking at my chassis with the paper label more closely for a stamped number. I just hadn't thought of it before this discussion. I hope to dig out the three sometime today after I take care of the wifely assigned chores. I plan to pull numbers off the parts to try to date them.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Thu 08, 2018 3:34 pm 
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I looked at my G500's and the results are very inconclusive.
I haven't pulled any of the chassis recently and I don't recall if the radio assembly date was stamped on the chassis shelf as was done in many of the later ZTO's. The only consistently dated part readily accessed is the speaker assembly so I took the numbers from them.
1) S/N 188835 (no S/N sticker): Speaker stamp - 343043, installed Oct 1950 or later.
2) S/N 264489 (no S/N sticker): Speaker stamp - 343101, installed Jan 1951 or later. IF can stamped 198051, manufactured Dec 1950.
3) S/N J-376899 (no stamped S/N): Speaker stamp - 343015, installed Apr 1950 or later.
Difference between #1 & #2 serials is over 75,000 and #2 & #3 is over 112,000, the difference between #1 & #3 is over 187,000.
I'm guessing dating will be a very hazy guestimate on anyone's part.
Were the "J" the initial issues of the G500? The earliest dated speaker was in the J-376899 chassis and the later issued speakers were installed in the chassis' lacking a sticker and with a lower serial number sequence.
Does anyone have any input that may reveal a way to date the G500's?
For the future I intend to make notes on all my ZTO's that include any stamped dates and date codes to see if anything can be used to indicate production/assembly dates of the units.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Thu 08, 2018 10:31 pm 
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Here is data I compiled from photos, etc. over the last eight years or so. I separated serial numbers containing the "J" prefixes from the serial numbers without J's. This is because those without the "J" have an embossed serial number, and the RETMA date code data indicates that each series was not manufactured concurrently-- the J's appear to have produced first, followed by the embossed serials.

Serial numbers collected in my database also show that there were production runs of other chassis types and models interspersed in the larger gaps in the above listed G500s, in the same practice starting with the 1936 Zenith model line. I have not included that data here, but have indicated breaks where this occured, using five asterisks.

"YYYYWW" denotes year (4 digits) followed by week of that year (2 digits) derived from the RETMA numbers, usually from the speaker, but sometimes from the tuner, or IF cans. EMB=embossed ser #, NO SP=no speaker, FR CHAS=from chassis only--i.e.: no cabinet.

SER # .........YYYYWW* ........NOTES
J101435 194928
J102243 194928
J103248
J103435
J103502 194932
J103558 194933
J103704 194933
J103817 195102 SPEAKER MUST HAVE BEEN REPLACED
J104065 194933 SN STICKER
J104073 194933 SER STICKER
J104435 194933
J104544
J104660 194934
J106240 194935
J106731 SER STICKER
J107053
J107354 194927
J107407 194931

*****
J173124 194939
J174931 194940
J177334 194947
J177674 STICKER
J177710 194947 SN STICKER
J177805 194946
J177815 194947 STICKER SER TAG
J177888 194947 SN STICKER
J177898 194947 SN STICKER

*****
J198233 194939
J198638 194939 SER STICKER
J198868 194939
J199642 194948
J199701 194947
J200159 194948
J200469 ?
J200698 194943 SN STICKER
J200922 194943 SN STICKER
J201413 194949
J201450 194948
J201463

*****
J215630 194948
J216233 194951
J216544 194950
J216778 194951
J217171 194951
J217739 194949 STICKER SER TAG
J218558 194951

*****
J242115 SN STICKER
J242151 194950
J242236 194950 SER STICKER
J242483 194950
J242676 NO SP
J242781 194943
J243054
J243101 194949
J244270 194948
J244513 195001
J244901 194949
J245277 195001
J245437 195003 SN STICKER
J245820 194942
J245829 194950
J246277 195001
J246924 195003

*****
J257059
J257112 195004
J257207 195004
J257227 195004
J257227 195001
J257563 195004 SER STICKER
J257846
J258732 195004
J259171 195004
J261318 195004
J261342 195007
J267161 195012

*****
J272409 195007
J272724 STICKER
J272922 195007
J273137 195010 SER STICKER, UL.
J273555
J273704 195010
J273868 195008
J273999 195010
J274262 195010
J274720 195012
J275034 195012
J275196
J275424 195010
J275485 195004
J275590 195012
J275679 195004
J275698 195012 SN STICKER
J275770 195004
J276031 195012
J276670 195007
J276761 195012 SN STICKER
J277003 195010

*****
J317506 194951 J"3"?

*****
J372653 195014
J374689 195012
J374691 195012
J375456 195010
J375460 195003
J375650 195012 SER STICKER
J376077 195014
J376345
J376460 195003
J376473 195004
J376827 195015
J376874 195004
J377225 195015
J377669 195004 STICKER SER TAG
J377753 195016
J378125 195003
J378509 SN STICKER
J379198 195003
J379203 195003

*****
36264 195015 EMBOSSED SN

*****
61675
62496 195025
70751
70981 195026
71774 195025
73929 195033
74019 195032
74644 195034

*****
137307 195036
139444 195038 FR CHAS EMB STAMP. UL STICKER
140494 195038

*****
177514 195041
184046 195044
185774 195046
186541 195047 FR CHAS EMB STAMP
186556 195043 UL STICKER
186909 195049
189002 195044 FR CHAS EMB STAMP. UL STICKER
191071 195034 FR CHAS EMB STAMP

*****
227324 195037
228738 195046
229999 195051
231661 195048
236950 EMBOSSED SN

*****
244526 195007
244778 195025

*****
258575 195104 FR CHAS EMB STAMP
259658 195104
260347 195104
261003 Verified sn 9/10/17.
261724 195104
261978 195104
262112 195104
262278 195104
262524 195104
266952 195108
268549 195110
268680 195048

*****
283128 195106

*****
332902 195048 FR CHAS EMB STAMP

I left out a couple at the end that appeared to have serial numbers intermingled with the H500 series. This is by no means every G500 I have encountered-- rather, it lists only those that I was motivated enough to record. I have listed only those that had legible serial numbers.

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 Post subject: Re: What a difference 125,412 can make
PostPosted: Nov Fri 09, 2018 2:10 am 
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Thank you for your post, Martin. When you have enough serial numbers with dated parts a pattern does emerge. There are a few anomalies but that would be due to some parts being used out of production sequence which would be likely with the volume of the radios being produced. I’ll keep your list, insert my serials and add any that I may encounter in the future.

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